ORCID Profile
0000-0001-9677-0306
Current Organisations
Imperial College London
,
Bangor University
,
University of New England
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Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.PHYSBEH.2012.03.015
Abstract: We tested the effects of different post-match recovery interventions on the subsequent hormonal responses to a physical stress-test and game performance in professional rugby union players. On four occasions, participants (n=12) completed a video session (1 h each) with accompanying coach feedback the day after a rugby union match. The interventions showed either video footage of player mistakes with negative coach feedback (NCF1) or player successes with positive feedback (PCF1). Both approaches were repeated (NCF2 and PCF2). In the following week, participants were assessed for their free testosterone (T) and cortisol (C) responses to a physical stress-test, pre-game T and game-ranked performance. The PFC1 and PCF2 approaches were both associated with significantly (p<0.01) greater free T (36% to 42%) responses to the stress-test when compared to NCF1 and NCF2 (16% to -3%), respectively. The PCF interventions were also associated with higher (28% to 51%) pre-game T concentrations and superior game-ranked performances than the NCF approaches (p<0.01). In conclusion, the post-game presentation of specific video footage combined with different coach feedbacks appeared to influence the free hormonal state of rugby players and game performance several days later. Therefore, within the sporting context, future behaviour and performance might be modified through the use of simple psychological strategies. These data are applicable to generalised human stress responses and their modifiability by prior exposure to a stressor.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2011
Publisher: Public Library of Science (PLoS)
Date: 09-02-2022
DOI: 10.1371/JOURNAL.PONE.0263772
Abstract: The 24 h responses to professional female netball-specific training were examined. British Superleague players ( n = 14 ) undertook a 90-min on-court training session incorporating key movement, technical, and scenario-specific match-play drills. Perceptual (mood, fatigue, soreness), neuromuscular (countermovement jump peak power output [PPO], PPO relative to mass [PPOrel], jump height [JH]), endocrine (salivary cortisol [C], testosterone [T] concentrations) and biochemical (creatine kinase concentrations [CK]) markers were assessed at baseline (immediately before Pre), and immediately, two and 24 hours after (+0h, +2h, +24h) training. Session (sRPE) and differential (dRPE) ratings of perceived exertion were recorded at +0h. Identification of clear between time-point differences were based on the 95% confidence interval (CI) for mean differences relative to baseline values not overlapping. At +0h, C (raw unit mean difference from baseline 95% CI: 0.16 0.06 to 0.25 μg·dl -1 ), T (32 20 to 45 pg⋅ml –1 ), CK (39 28 to 50 u·L -1 ), PPOrel (2.4 0.9 to 3.9 W·kg -1 ) and PPO (169 52 to 286 W) increased. At +2h, fatigue (15 7 to 24 AU), CK (49 38 to 60 u·L -1 ), and soreness (14 3 to 25 AU) increased, while T (-24 -37 to -11 pg⋅ml –1 ) and mood (-20 -27 to -12 AU) reduced. At +24h, CK increased (25 13 to 36 u·L -1 ) whereas PPOrel (-1.6 -3.2 to -0.1 W·kg -1 ) and JH (-0.02 -0.03 to -0.08 m) reduced. Responses were variable specific, and recovery of all variables did not occur within 24h. The residual effects of the prior stimulus should be accounted for in the planning of training for professional female netball players.
Publisher: Elsevier BV
Date: 11-2001
DOI: 10.1016/S0031-9384(01)00608-4
Abstract: The effects of environmental conditions on temperature rhythms were investigated in ewe lambs at pasture. Two groups of 20 lambs had heart rate (HR), vaginal temperature (T(v)), ear-canal temperature (T(c)) and ear-pinna temperature (T(p)) monitored continuously for 3 days. Climatic conditions were recorded at the same time and Temperature Humidity Index (THI) calculated. One group experienced fine clear weather for the 3 days, the other group experienced 2 days of heavy rain. During periods of fine weather, the daily rhythm for T(v) and T(c) was monophasic. However, heavy rain and a constant THI reduced the litude of the recorded temperature rhythms. Daily T(v) and T(c) patterns correlated strongly with THI, with a phase lag of 2 h. Peak T(v) and T(c) were at approximately 17:00 h each day. Mean maximum daily litudes were approximately 1.3 degrees C for T(v) and T(c). Mean T(v) was 39.3+/-0.1 and 39.6+/-0.1 for weeks 1 and 2, respectively, while mean T(c) was 38.9+/-0.1 and 39.2+/-0.1. Changes in T(v) and T(c) were closely correlated. We conclude that climate has a major effect on body temperature rhythms.
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.PHYSBEH.2013.03.013
Abstract: Testosterone has been related to improved acute neuromuscular performance in athletic populations. It is our contention that testosterone may also contribute to improved volitional motivation and, when monitored longitudinally, may provide one proxy marker for readiness to perform. Twelve female netball players provided saliva s les prior to five standardized training sessions in which they completed a maximal-distance medicine ball throw, and then 3 sets of bench press and then back squat using a self-selected load perceived to equal a 3-repetition maximum load. Additional repetitions were encouraged when possible and total voluntary workload was calculated from the product of the load lifted and repetitions performed. Relative salivary testosterone levels as a group were correlated with bench press (r=0.8399 p=0.0007) and squat (r=0.6703 p=0.0171) self-selected workload, as well as maximal medicine ball throw performance (r=0.7062 p=0.0103). In idual salivary testosterone, when viewed relatively over time, demonstrated strong relationships with self-selected workloads during an in-season training period in female netball players. As such, daily variations in testosterone may provide information regarding voluntary training motivation and readiness to perform in elite athletic populations. Psychological and behavioral aspects of testosterone may have the potential to enhance training adaptation by complementing the known anabolic and permissive properties of testosterone.
Publisher: Springer Science and Business Media LLC
Date: 19-01-2016
DOI: 10.1007/S10484-015-9330-9
Abstract: Support and management staff in elite sport experience work-related stress and emotional disturbance to a similar extent as athletes (Fletcher and Wagstaff 2009). The resonant frequency breathing technique (Lehrer et al. 2000) can inhibit autonomic changes associated with stressful situations or events and as such provides a potential emotional regulation tool. The present study utilised five practitioner-led heart rate variability (HRV) biofeedback sessions and home practice via mobile applications to train support and management staff (n = 9) in resonant frequency breathing techniques. Although baseline HRV did not change from pre to post training, participants increased total HRV (i.e., SDNN p = .006), parasympathetic HRV (i.e., RMSSD p = .028) and HRV reflective of baroreflex function (i.e., low frequency power p = .018) while accurately performing resonant frequency breathing without a breath pacer. Post-intervention questionnaire data revealed an increase (p = .032) in habitual use of somatic strategies for emotional regulation, and social validation data suggested that the technique enhanced emotional regulation at home, work and during international competition. HRV biofeedback and the resonant frequency technique provided an on-demand emotional regulation technique for elite sport support and management staff.
Publisher: Public Library of Science (PLoS)
Date: 12-09-2018
Publisher: Springer Science and Business Media LLC
Date: 25-02-2021
Publisher: Informa UK Limited
Date: 12-1991
DOI: 10.1080/00480169.1991.35677
Abstract: Passing an electric current (50 Hz, 400 V open circuit, current limited to 1.5 A) from two electrodes acting as a common single electrode set applied on each side of the dorsal surface of the neck (cervical vertebrae C2 to C5 region) to another placed on the brisket of young bulls causes fibrillation of the cardiac muscle, does not induce epileptiform changes in the electroencephalogram, and produces a state of body rigidity. Passing the same electric current through the same neck electrodes, now acting as two separate electrodes, without the brisket electrode, does induce epileptiform activity similar to that seen with head-only stunning, does not fibrillate the heart, and produces a state of limb rigidity lasting for some time after the stun. Given that the presence of epileptiform activity is a criterion for effective electrical stunning and is indicative of insensibility, neck-to-brisket stunning as described here does not appear to be humane.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2017
DOI: 10.1519/JSC.0000000000001505
Abstract: Russell, M, Birch, J, Love, T, Cook, CJ, Bracken, RM, Taylor, T, Swift, E, Cockburn, E, Finn, C, Cunningham, D, Wilson, L, and Kilduff, LP. The effects of a single whole-body cryotherapy exposure on physiological, performance, and perceptual responses of professional academy soccer players after repeated sprint exercise. J Strength Cond Res 31(2): 415–421, 2017—In professional youth soccer players, the physiological, performance, and perceptual effects of a single whole-body cryotherapy (WBC) session performed shortly after repeated sprint exercise were investigated. In a randomized, counterbalanced, and crossover design, 14 habituated English Premier League academy soccer players performed 15 × 30 m sprints (each followed by a 10 m forced deceleration) on 2 occasions. Within 20 minutes of exercise cessation, players entered a WBC chamber (Cryo: 30 seconds at −60° C, 120 seconds at −135° C) or remained seated (Con) indoors in temperate conditions (∼25° C). Blood and saliva s les, peak power output (countermovement jump), and perceptual indices of recovery and soreness were assessed pre-exercise and immediately, 2-hour and 24-hour postexercise. When compared with Con, a greater testosterone response was observed at 2-hour (+32.5 ± 32.3 pg·ml −1 , +21%) and 24-hour (+50.4 ± 48.9 pg·ml −1 , +28%) postexercise (both P = 0.002) in Cryo (trial × treatment interaction: P = 0.001). No between-trial differences were observed for other salivary (cortisol and testosterone/cortisol ratio), blood (lactate and creatine kinase), performance (peak power output), or perceptual (recovery or soreness) markers (all trial × treatment interactions: P 0.05) all of which were influenced by exercise (time effects: all P ≤ 0.05). A single session of WBC performed within 20 minutes of repeated sprint exercise elevated testosterone concentrations for 24 hours but did not affect any other performance, physiological, or perceptual measurements taken. Although unclear, WBC may be efficacious for professional soccer players during congested fixture periods.
Publisher: Informa UK Limited
Date: 2001
Abstract: Baits containing sodium monofluoroacetate (1080) are commonly used in New Zealand during feral pest control operations. However, each year, a number of domestic dogs are unintentionally killed during these control operations, and a suitable antidote to 1080 intoxication is required. The primary toxic mechanism of 1080 is well known. However, as with other pathologies where energy deprivation is the main effect of intoxication, the cascade of effects that arises from this primary mechanism is complex. At present, putative antidotes for 1080 are generally unable to address the primary mechanism of intoxication but such agents may be able to control the cascade of secondary effects, which can result during intoxication. Part of the reason for this is that targeting the cascade can provide a longer window of time for antidote success. We have undertaken studies that identified some of the central nervous system (CNS) and systemic pathophysiological cascades caused by 1080 intoxication. Using this information we designed antidotes, on the basis of preventing different steps in this cascade. In the chicken model targeting systemic changes, in particular reducing effects of nitric oxide derivatives generated in cardiac muscle, proved successful in reducing fatality associated with 1080. In rats and sheep, targeting the CNS with a number of compounds including: glutamate calcium and dopamine antagonists gamma amino butyric acid agonists, and astressin-like compounds reduced fatalaties. However, to be successful in the rat and sheep model a given antidote needed to move quickly from systemic circulation across the blood brain barrier and into the CNS. The work also suggests ways in which specific biomarkers of 1080 exposure may be developed with respect to different species.
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.JSAMS.2018.02.015
Abstract: Rugby union is a high intensity intermittent sport, typically analysed via set time periods or rolling average methods. This study reports the demands of international rugby union via global positioning system (GPS) metrics expressed as mean ball in play (BiP), maximum BiP (max BiP), and whole match outputs. Single cohort cross sectional study involving 22 international players, categorised as forwards and backs. A total of 88 GPS files from eight international test matches were collected during 2016. An Opta sportscode timeline was integrated into the GPS software to split the data into BiP periods. Metres per min (mmin Whole match metrics were significantly lower than all BiP metrics (p<0.001). Mean and max BiP HML, (p<0.01) and HSR (p<0.05) were significantly higher for backs versus forwards, whereas Coll were significantly higher for forwards (p<0.001). In plays lasting 61s or greater, max BiP mmin This study uses a novel method of accurately assessing the BiP demands of rugby union. It also reports typical and maximal demands of international rugby union that can be used by practitioners and scientists to target training of worst-case scenario's equivalent to international intensity. Backs covered greater distances at higher speeds and demonstrated higher HML, in general play as well as 'worst case scenarios' conversely forwards perform a higher number of collisions.
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.JSAMS.2019.08.291
Abstract: This study profiled the 24h neuromuscular, endocrine and mood responses to a single versus a double training day in soccer players. Repeated measures. Twelve semi-professional soccer players performed small-sided-games (SSG's 4 vs 4+goalkeepers 6×7-min, 2-min inter-set recovery) with neuromuscular (peak-power output, PPO jump height, JH), endocrine (salivary testosterone, cortisol), and mood measures collected before (pre) and after (0h, +24h). The following week, the same SSG protocol was performed with an additional lower body strength training session (back-squat, Romanian deadlift, barbell hip thrust 4×4 repetitions, 4-min inter-set recovery 85% 1 rep-max) added at 2h after the SSG's. Between-trial comparisons revealed possible to likely small impairments in PPO (2.5±2.2Wkg These data highlight that performance of two training sessions within a day resulted in possible to very likely small impairments of neuromuscular performance, mood score and endocrine markers at +24h relative to a single training session day. A strategy of alternating high intensity explosive training days containing multiple sessions with days emphasising submaximal technical/tactical activities may be beneficial for those responsible for the design and delivery of soccer training programs.
Publisher: BMJ
Date: 03-2008
Abstract: The primary purpose of this study was to investigate the relationship between the pre-game to post-game changes in creatine kinase concentration (Delta[CK]) and impact-related game statistics in elite rugby union players. Twenty-three elite male rugby union players each provided interstitial fluid s les obtained via electrosonophoresis (ESoP) 210 min before and within a maximum time of 30 min after up to five rugby union games. Specific game statistics that were deemed to be important in determining the relationship between impact and [CK] were obtained from AnalyRugby software for each in idual player. Regression equations to predict Delta[CK] from game statistics were created using a backwards random-effects maximum likelihood regression. The Delta[CK] (mean (SD)) from pre-game to post-game was 926.8 (204.2) IU. Game time and time defending were significantly correlated to Delta[CK] in both the forwards and backs. The predicted Delta[CK] (mean (95% confidence limit)) was 1439.8 (204.9) IU for the forwards and 545.3 (78.0) IU for the backs and was significantly correlated with the actual Delta[CK] (r = 0.69 and r = 0.74). CK increased from pre-game to post-game in a position-specific manner. A large proportion of the Delta[CK] can be explained by physical impact and thus can be predicted using a prescribed number of game statistics. As the Delta[CK] is an indicator of muscle damage, the prediction of Delta[CK] provides a theoretical basis for recovery strategies and adjustment of subsequent training sessions after rugby union games.
Publisher: Springer Science and Business Media LLC
Date: 05-1997
DOI: 10.1038/NBT0597-467
Abstract: An electrochemical immunosensor for real-time determination of corticosteroids, a group of steroidal hormones, is reported. The sensor measures competitive binding of endogenous corticosteroid and a corticosteroid-peroxidase conjugate with antibodies, immobilized on a platinum electrode, by monitoring of peroxidase activity. The electrode is encased within a dialysate membrane, which separates the electrode environment from the s led fluid, allowing corticosteroid to equilibrate across the membrane. This permits measurements to be made in vivo. The small size of the probe (350 microns D) allows implantation into tissue or circulatory systems. The electrode was viable for 200 to 400 sequential measurements and at least 48 h in vivo. Detection sensitivity is 0.2 to 0.6 microgram/100 ml of cortisol or corticosterone. The results suggest the possibility of monitoring hormones in real-time within the blood or organ systems of conscious animals.
Publisher: Termedia Sp. z.o.o.
Date: 2019
Publisher: Wiley
Date: 30-01-2018
DOI: 10.1111/SMS.13041
Abstract: This study investigated salivary testosterone (sal-T) variation across the menstrual cycle in female athletes, at different competitive levels, and its association with motivation and neuromuscular power. Six elite and 16 non-elite female athletes were monitored on days 7 (D7), 14 (D14), and 21 (D21) across 3 menstrual cycles for basal sal-T concentrations and self-appraised motivation to train and compete. Two further measures were taken on D7, D14, and D21 across 2 menstrual cycles: (1) the sal-T response (delta change) to a physical stress test and (2) peak power (PP) response to a 6-second cycle sprint following a post-activation potentiation (PAP) stimulus. Basal sal-T concentrations increased by 17 ± 27% from D7 to D14 before decreasing by -25 ± 43% on D21 (P 102%) who showed larger menstrual changes. Motivation, sal-T reactivity to stress, and the PP responses to a PAP stimulus also varied by testing day (P < .05), in parallel with basal sal-T and in favor of the elite group. Furthermore, stronger within-subject relationships (P < .001) between basal sal-T and motivation emerged in the elites (r = .70-.75) vs the non-elite group (r = .41-.50). In conclusion, menstrual cycle changes in sal-T were more obvious in high-performing female athletes with higher sal-T concentrations. This was accompanied by greater training motivation, a more pronounced sal-T response to a physical stressor and greater neuromuscular power in the elite group. These results support observations that female athletes with higher T are more represented at elite levels of performance.
Publisher: SAGE Publications
Date: 02-03-2023
DOI: 10.1177/17479541231160229
Abstract: High-performance sport is still not appropriately addressing issues that perpetuate women's underrepresentation in elite sport coaching and leadership. Therefore, it is also unlikely representation for other minority groups in high-performance sport will be achieved any time soon. For high-performance sport to progress, there is an opportunity to create environments that foster a variety of coaching styles with erse racial, ethnic and gender identities. This paper points to statistics from elite football and Olympic sports to highlight the issue of the underrepresentation of women coaches in high-performance sport and draws upon a range of literature to inform an evidence-based and strategic approach to designing development in the context of increasing coach and leader gender ersity in these settings. It explores leadership in high-performance sport, learning and development, and high-performance sport environments. We argue future focused development should prepare high-performance sport leaders to intervene at an environmental level where they provide leadership, facilitate performance enablers, and engage athletes and performance staff to shape cultural change
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2011
Publisher: Human Kinetics
Date: 11-2020
Abstract: Purpose : Reported associations between vitamin 25(OH)D and exercise performance are equivocal, perhaps due to complex interplay with cortisol and testosterone. In this study, the authors investigated serum 25(OH)D and cortisol as moderators of the testosterone relationship with exercise performance in adolescent male athletes. Methods : A total of 88 ice hockey players were assessed for serum 25(OH)D, cortisol, testosterone, body composition, and exercise performance, based on countermovement jump power and muscle torque. The authors tested independent relationships, before examining complex interactions via moderated regression analyses. Results : Most athletes (62.5%) exhibited a suboptimal (20–30 ng·mL −1 ) serum 25(OH)D concentration, whereas 9.1% of athletes were deficient ( ng·mL −1 ). Serum 25(OH)D was not related to performance when controlling for testing year, age, and fat mass. Further modeling revealed a significant hormonal interaction. Specifically, in low-25(OH)D subjects, testosterone predicted countermovement jump power at a high ( β = 7.10, effect size = .43, P .01), but not low ( β = −3.32, effect size = −.20, P = .09), cortisol concentration. Conclusions : Serum 25(OH)D was a poor predictor of exercise performance, but it did moderate (with cortisol) the testosterone link to muscle power. Notably, this relationship emerged among in iduals with a 25(OH)D concentration (∼22 ng·mL −1 ) approaching the deficiency cutoff. Viewing 25(OH)D as a moderating, rather than dose responsive, variable could help explain equivocal cross-sectional associations.
Publisher: Elsevier BV
Date: 02-2002
DOI: 10.1016/S0031-9384(01)00658-8
Abstract: Experiments were conducted in both sheep and humans to evaluate techniques for rapid s ling and measurement of testosterone, insulin, 17-beta estradiol, cortisol and glucose collected in saliva or transdermal exudate. Ultrasound and an electric current facilitated the latter collection. All but insulin were successfully measured in saliva, under resting conditions, and the measured hormones correlated best with blood levels 20-40 min prior to the saliva collection. With imposition of, and recovery from, an exercise stress, this correlation was weakened irrespective of considering the time lag between blood measures during this period and subsequent changes in saliva values. Provided an initial transdermal flux was established, all the hormones and glucose were successfully measured in the transdermal exudate at levels correlating with blood measures at the time of collection, and this held across stressor application and recovery. The transdermal exudate s ling and measurement apparatus is relatively portable, enabling noninvasive collection and analyte measurement, rapidly, at the site where the experiment is being conducted with minimal interference to subjects. This potentially offers a tool of considerable value to endocrine studies.
Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1016/J.JSAMS.2013.04.016
Abstract: To determine if a morning training session could alter afternoon physical performance. Moreover, as testosterone (T) and cortisol (C) concentrations are significant predictors of physical performance, and both show circadian declines across the day, we examined the effects of morning training on diurnal T and C responses. Eighteen semi-professional rugby union players completed this randomised and counter-balanced study. Following morning saliva collection (0900 h), players completed a control (rested), Sprint (5 × 40 m) or Weights (3 repetition-maximum [RM] bench press and squat) trial. In the afternoon (15:00 h) of each trial, a further saliva s le was collected before players completed a performance test (3 RM back squat and bench press, 40 m sprint, countermovement jump [CMJ]). Salivary T concentrations declined from am to pm under Control and Sprint, but not under Weights. Delta T, from am to pm, was greater under Control (-10.9 ± 2.4 pg ml(-1)) compared to Sprints (-6.2 ± 7.1 pg ml(-1)) and Weights (-1.2 ± 5.5 pg ml(-1)) (p ≤ 0.001). Delta C, from am to pm, was greater under Control compared to both Sprint and Weights (p<0.05). Players elicited better CMJ peak power, 40-m time, 3 RM bench and squat performance under Weights compared with Control and Sprint (p<0.05). Faster 40-m times were seen under Sprint, when compared to Control (p<0.05). Performing morning strength training is associated with improved physical performance in the afternoon. Additionally, the circadian decline in T concentrations appeared offset by morning training. However, it is unclear if T concentrations are, in part, causal of these improved responses or simply a reflective marker.
Publisher: Informa UK Limited
Date: 02-1994
Publisher: Informa UK Limited
Date: 08-1996
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.PHYSBEH.2018.11.027
Abstract: The concept of competition has implications for educational contexts, as hormonal and emotional changes under competitive stress can modulate learning and memory processes. This study examined the impact of a competitive learning environment and associated hormonal and emotional responses on skill acquisition and expression in a medical domain. Using a cross-over design, sixteen male medical students participated in a competitive (in pairs facing each other) and non-competitive (alone) learning situation. In each treatment, an instructional video was followed by a timed straight-line suture evaluation with anxiety and competitiveness recorded. Salivary testosterone (T) and cortisol (C) were assessed at rest, before and after evaluation to quantify changes in T (ΔT) and C (ΔC). These procedures were followed by two sessions of self-directed training before retesting. Paired learning produced a larger positive ΔT (5.9-7.8% vs. 2.0-5.3%) and ΔC (7.6% vs. 3.3%), which was accompanied by more anxiety and elevated competitiveness (p < .01). Anxiety declined and suturing abilities improved over time (p < .001), irrespective of the learning approach, with resting C concentrations decreasing when learning alone (p < .05). Some ΔT and ΔC measures correlated (r = 0.40 to 0.65) with anxiety and competitive desire with paired learning only, whereas the ΔC was linked to suturing performance (r = -0.35) when learning alone. In summary, a tacit competition in a natural learning situation promoted more pronounced hormonal and emotional responses. However, skill acquisition and its expression improved to a similar extent in both situations of competitive and non-competitive assessment. Different adaptive pathways for skill expression and development emerged from this work.
Publisher: Elsevier BV
Date: 10-2018
DOI: 10.1016/J.JSAMS.2018.02.012
Abstract: The effects of vascular occlusion on recovery of physiological and neuromuscular markers over 24h, and hormonal reactivity to subsequent exercise were investigated. Counterbalanced, randomised, crossover. Academy rugby players (n=24) completed six 50-m sprints (5-min inter-set recovery) before occlusion cuff application (thighs) and intermittent inflation to 171-266mmHg (Recovery) or 15mmHg (Con) for 12-min (two sets, 3-min repetitions, 3-min non-occluded reperfusion). Countermovement jumps, blood (lactate, creatine kinase), saliva (testosterone, cortisol), and perceptual (soreness, recovery) responses were measured before (baseline) and after (post, +2h, +24h) sprinting. Saliva was s led after a 30-min resistance exercise session performed 24h after sprinting. Although sprinting (total: 40.0±2.8s, p=0.238 average: 6.7±0.5s, p=0.674) influenced creatine kinase (p<0.001, +457.1±327.3μL Vascular occlusion had no effect on physiological or neuromuscular markers 2h or 24h after sprinting or in response to a physical stress test.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.YHBEH.2019.04.007
Abstract: Literature suggests that women experience ovulatory shifts in risk-taking behaviours across different domains, which might be partly attributed to changes in testosterone (T). Thus, we investigated associations between menstrual variability in T concentrations and economic risk-related decisions among athletic women. Thirty-five women were monitored across three consecutive menstrual cycles. Testing occurred on day seven (D7), 14 (D14) and 21 (D21) following the onset of menses. The morning (7 to 8 am) assessment of salivary T (sal-T) and cortisol (sal-C) was followed by the economic Hawk-Dove game (11 am to 12 pm) played in pairs, where hawk decisions were used to index risk. Morning sal-T concentration increased from D7 to D14, before decreasing on D21 (p < 0.001), representing moderate effect size (ES) changes of 0.6 to 0.8. Morning sal-C did not vary over time. Hawk choices paralleled the sal-T results, being elevated on D14 (p < 0.001) with large ES changes of 1.8. Regression analyses revealed that morning sal-T concentration was positively related (p ≤ 0.01) to the number of hawks chosen between- (beta = 0.47) and within-participants (beta = 0.10) when controlling for training hours and menstrual day. In summary, the risk-related choices of athletic women during a dyadic contest covaried with morning sal-T concentrations across the menstrual cycle. Both outcomes were positively correlated on a within- and between-person level. Confirming the major sources of T variation across the menstrual cycle, whilst discerning its relationship with other risk-related behaviours, would be worthwhile avenues for research.
Publisher: Public Library of Science (PLoS)
Date: 18-03-2015
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.YHBEH.2018.06.011
Abstract: Human gaze is an important indicator of dominant and submissive behaviours related to positioning in a social hierarchy. This study investigated face gazing after a chance-determined contest and its linkage to salivary testosterone (sal-T) reactivity in athletic women. Twenty-six women athletes completed a coin-toss game on days 7 (D7), 14 (D14) and 21 (D21) of a single menstrual cycle. The game was played against an unknown opponent of similar age with the winner congratulated and rewarded with all coins. Gazing towards an opponent's head or face was timed after each contest (over 2 min) from video footage. Salivary T (sal-T) was assessed before and 15 min after these contests. The sal-T residuals increased after winning and decreased after losing on D7, D14 and D21 (p < 0.05). Gaze times were longer after a loss (M = 7.8 s) than a win (M = 3.1 s) across all days. Regression analyses revealed that the sal-T residuals and contest outcome interacted to predict gaze time. Upon deconstruction we found that, when losing a contest, a larger sal-T response (i.e., smaller decline) predicted a longer gaze (β = 1.71, p = 0.004), but no association was evident when winning (β = -0.06, p = 0.821), and these slope patterns differed (p = 0.011). In conclusion, winning a contest by chance increased sal-T responsivity and decreased opponent gaze across the menstrual cycle. A positive relationship between in idual sal-T reactivity and gaze duration was observed, but only when losing. These preliminary results support suggestions that women's T may help modulate post-competition behaviours (e.g., face gazing) possibly to achieve social cohesion and cooperation.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JSAMS.2016.09.012
Abstract: Biochemical (e.g. creatine kinase (CK)) and neuromuscular (e.g. peak power output (PPO)) markers of recovery are expensive and require specialist equipment. Perceptual measures are an effective alternative, yet most validated scales are too long for daily use. This study utilises a longitudinal multi-level design to test an adapted Brief Assessment of Mood (BAM+), with four extra items and a 100mm visual analogue scale to measure recovery. Elite under-21 academy soccer players (N=11) were monitored across five games with data (BAM+, CK and PPO) collected for each game at 24h pre, 24h and 48h post-match. Match activity data for each participant was also collected using GPS monitors on players. BAM+, CK and PPO had significant (p<.05) linear and quadratic growth curves across time and games that matched the known time reports of fatigue and recovery. Multi-level linear modelling (MLM) with random intercepts for 'participant' and 'game' indicated only CK significantly contributed to the variance of BAM+ scores (p<.05). Significant correlations (p<.01) were found between changes in BAM+ scores from baseline at 24 and 48h post-match for total distance covered per minute, high intensity distance covered per minute, and total number of sprints per minute. Visual and inferential results indicate that the BAM+ appears effective for monitoring longitudinal recovery cycles in elite level athletes. Future research is needed to confirm both the scales reliability and validity.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2012
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.JSAMS.2019.10.011
Abstract: Research has linked physiological (e.g., hormonal, affective, fatigue) outcomes to performance indicators in rugby competition, but no work has integrated and contextualised these factors within a test-match environment. We addressed this gap by monitoring 29 athletes from a training squad across eight international rugby matches. Longitudinal observational study. Pre-match (8-9am) measures of salivary testosterone and cortisol concentrations, sleep duration, pulse rate, muscle soreness, stress, mood, and motivation were taken. Contextual factors were playing time, internal training load (ITL), test-match experience, opponent ranking, and crowd size. Performance was indexed by coach and player ratings of performance (CRP, PRP) and quantitative metrics offloads, turnovers, runs with ball in hand (RWB), tackles, passes, and defenders beaten (DFB). Morning cortisol, sleep and mood were positively related to CRP and PRP (standardised coefficient estimates from 0.17 to 0.22). Cortisol, sleep, stress, mood and motivation were associated with one (or more) of turnovers, RWB, tackles, passes and DFB (incidence rate ratio [IRR] from 0.74 to 1.40). Playing time was positively related to all quantitative performance indicators (IRR from 1.01 to 1.04) with ITL, opponent ranking, and crowd size predicting selected outputs (IRR from 0.89 to 1.15). The explanatory models varied (conditional R Multiple physiological and contextual factors appear to contribute to player performance in international rugby competition. Measurement of these factors may guide training and management practices, a potential practical consequence but also advancing understanding from marker to causal link.
Publisher: Elsevier BV
Date: 1992
DOI: 10.1016/0034-5288(92)90057-9
Abstract: In sheep, administration of a combination of zolazepam and tiletamine hydrochloride resulted in a dose dependent reduction in the duration of epileptic activity induced by an electric stun applied to the head. The compound also lengthened the normal period of reflex suppression that occurs after a stun. Excitatory amino acid receptor antagonists (2-amino-7-phosphonoheptanoic and 2-amino-5-phosphonovaleric acids) also reduced the duration of epileptic activity following an electric stun. These drugs did not alter the time of pedal and ear pinch reflex suppression. Administration of bicuculline (a gamma amino-4-butyric acid [GABA] receptor antagonist) reduced the period of stun induced reflex suppression and increased seizure duration. Administration of a GABA receptor agonist, baclofen, increased the duration of reflex suppression. The results suggest that the development of epileptiform-like activity following application of an electric current to the head is dependent upon excitatory amino acid receptors. The reflex suppression that also arises following an electric stun is contributed to by the activation of GABA receptor mechanisms.
Publisher: Springer Science and Business Media LLC
Date: 20-10-2015
DOI: 10.1007/S00464-015-4584-0
Abstract: Surgical training and practice is stressful, but adaptive changes in the stress circuitry (e.g. perceptual, physiological, hormonal, neural) could support skill development. This work examined skill acquisition and stress adaptations in novice surgeons during laparoscopic surgery (LS) training and detraining. Twelve medical students were assessed for skill performance after 2 h (BASE), 5 h (MID) and 8 h (POST) of LS training in weeks 1-3, and then after 4 weeks of no training (RETEST). The stress outcomes included state anxiety, perceived stress and workload, heart rate (HR), heart rate variability (HRV), and salivary testosterone and cortisol concentrations. Functional near-infrared spectroscopy was used to assess cortical oxygenation change, as a marker of prefrontal cortex (PFC) activity. Skill performance improved in every session from BASE (p < 0.01), with corresponding decreases in state anxiety, stress, workload, low- and high-frequency HRV in the MID, POST and/or RETEST sessions (p < 0.05). Left and right PFC were symmetrically activated within each testing session (p < 0.01). The stress and workload measures predicted skill performance and changes over time (p < 0.05), with state anxiety, mean HR and the HRV measures also showing some predictive potential (p < 0.10). A 3-week LS training programme promoted stress-related adaptations likely to directly, or indirectly, support the acquisition of new surgical skills, and many outcomes were retained after a 4-week period without further LS training. These results have implications for medical training and education (e.g. distributed training for skill development and maintenance, stress resource and management training) and highlighted possible areas for new research (e.g. longitudinal stress and skill profiling).
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2010
Publisher: Elsevier BV
Date: 04-2020
DOI: 10.1016/J.AMJSURG.2019.04.003
Abstract: This study examined a possible link between the elective preferences of medical students (surgical vs. non-surgical) and their emotional and hormonal responses to a psychological stressor. Forty medical students completed a laboratory stressor comprising of 10 puzzles in a time-limited format. Emotional state was assessed before (competitiveness, anxiety) and after (stress, enjoyment) testing, along with changes in salivary testosterone (ΔT) and cortisol (ΔC). Comparisons were made according to in idual preferences for a surgical (n = 16) or non-surgical (n = 24) elective. Those seeking surgery had a lower 2D:4D (d = -2.0) with higher competitiveness scores (d = 2.7), but less anxiety (d = -0.9) and stress (d = -0.8). They also had a larger ΔT (17% vs. 6%) and smaller ΔC (7% vs. 12%) from the non-surgical cohort. Significant interrelationships were observed between 2D:4D, competitiveness, anxiety, stress and hormones. In summary, in students at a career stage of considering options in medicine, differences in stress responsivity were seen in those considering surgery, as compared to those considering other specialities.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JSAMS.2016.03.007
Abstract: Athletes are often required to undertake multiple training sessions on the same day with these sessions needing to be sequenced correctly to allow the athlete to maximize the responses of each session. We examined the acute effect of strength and speed training sequence on neuromuscular, endocrine, and physiological responses over 24h. 15 academy rugby union players completed this randomized crossover study. Players performed a weight training session followed 2h later by a speed training session (weights speed) and on a separate day reversed the order (speed weights). Countermovement jumps, perceived muscle soreness, and blood s les were collected immediately prior, immediately post, and 24h post-sessions one and two respectively. Jumps were analyzed for power, jump height, rate of force development, and velocity. Blood was analyzed for testosterone, cortisol, lactate and creatine kinase. There were no differences between countermovement jump variables at any of the post-training time points (p>0.05). Likewise, creatine kinase, testosterone, cortisol, and muscle soreness were unaffected by session order (p>0.05). However, 10m sprint time was significantly faster (mean±standard deviation speed weights 1.80±0.11s versus weights speed 1.76±0.08s p>0.05) when speed was sequenced second. Lactate levels were significantly higher immediately post-speed sessions versus weight training sessions at both time points (p<0.05). The sequencing of strength and speed training does not affect the neuromuscular, endocrine, and physiological recovery over 24h. However, speed may be enhanced when performed as the second session.
Publisher: Informa UK Limited
Date: 08-01-1994
Publisher: Informa UK Limited
Date: 11-01-1995
Publisher: Elsevier BV
Date: 05-2015
DOI: 10.1016/J.JSAMS.2014.04.004
Abstract: During congested fixture periods in team sports, limited recovery time and increased travel hinder the implementation of many recovery strategies thus alternative methods are required. We examined the impact of a neuromuscular electrical stimulation device on 24-h recovery from an intensive training session in professional players. Twenty-eight professional rugby and football academy players completed this randomised and counter-balanced study, on 2 occasions, separated by 7 days. After baseline perceived soreness, blood (lactate and creatine kinase) and saliva (testosterone and cortisol) s les were collected, players completed a standardised warm-up and baseline countermovement jumps (jump height). Players then completed 60 m × 50 m maximal sprints, with 5 min recovery between efforts. After completing the sprint session, players wore a neuromuscular electrical stimulation device or remained in normal attire (CON) for 8 h. All measures were repeated immediately, 2 and 24-h post-sprint. Player jump height was reduced from baseline at all time points under both conditions however, at 24-h neuromuscular electrical stimulation was significantly more recovered (mean±SD neuromuscular electrical stimulation -3.2±3.2 vs. CON -7.2±3.7% P<0.001). Creatine kinase concentrations increased at all time points under both conditions, but at 24-h was lower under neuromuscular electrical stimulation (P 0.05). Neuromuscular electrical stimulation improves recovery from intensive training in professional team sports players. This strategy offers an easily applied recovery strategy which may have particular application during sleep and travel.
Publisher: Public Library of Science (PLoS)
Date: 08-11-2016
Publisher: Wiley
Date: 22-08-2012
DOI: 10.1002/AJHB.22302
Abstract: To compare the baseline free testosterone (T) and cortisol (C) concentrations of elite and non-elite female athletes. Eighteen females from different sports (track and field, netball, cycling, swimming, bob skeleton) were monitored over a 12-week period. Baseline measures of salivary free T and C concentrations were taken weekly prior to any training. The elites (n = 9) and non-elites (n = 9) were classified as international and national level competitors, respectively, with both groups matched by sport. The pooled free T concentrations of the elites (87 pg/ml) were significantly higher than the non-elites (41 pg/ml) and consistently so across all weekly time points (P < 0.001). Pooled free C concentrations were also greater in the elite group (2.90 ng/ml) than the non-elites (2.32 ng/ml) (P < 0.01). The pooled baseline T and C measures were higher in elite female athletes than non-elites. Higher free T and C concentrations could indicate a greater capacity for physical performance at higher work rates, which is commensurate with the demands of elite sport. Speculatively, the T differences observed could influence female behavior and thereby help to regulate sporting potential.
Publisher: American Physiological Society
Date: 15-05-2013
DOI: 10.1152/JAPPLPHYSIOL.01419.2012
Abstract: Dihydrotestosterone (DHT) exerts both functional and signaling effects extending beyond the effects of testosterone in rodent skeletal muscle. As a primer for investigating the role of DHT in human skeletal muscle function, this study aimed to determine whether circulating DHT is acutely elevated in men following a bout of repeat sprint exercise and to establish the importance of training status and sprint performance to this response. Fourteen healthy active young men (V̇o 2max 61.0 ± 8.1 ml·kg body mass −1 ·min −1 ) performed a bout of repeat sprint cycle exercise at a target workload based on an incremental work-rate maximum (10 × 30 s at 150% W max with 90-s recovery). Venous blood s les were collected preexercise and 5 and 60 min after exercise. Five minutes after exercise, there were significant elevations in total testosterone (TT P 0.001), free testosterone (FT P 0.001), and DHT ( P = 0.004), which returned to baseline after 1 h. Changes in DHT with exercise (5 min postexercise − preexercise) correlated significantly with changes in TT ( r = 0.870 P 0.001) and FT ( r = 0.914 P 0.001). Sprinting cadence correlated with changes in FT ( r = 0.697 P = 0.006), DHT ( r = 0.625 P = 0.017), and TT ( r = 0.603 P = 0.022), and habitual training volume correlated with the change in TT ( r = 0.569, P = 0.034). In conclusion, our data demonstrate that DHT is acutely elevated following sprint cycle exercise and that this response is influenced by cycling cadence. The importance of DHT in the context of exercise training and sports performance remains to be determined.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2013
Publisher: Springer Science and Business Media LLC
Date: 26-07-2018
DOI: 10.1007/S40279-018-0962-9
Abstract: Depending upon competition regulations, the laws of soccer allow between three and an unlimited number of substitutions that can be made on either a permanent or rolling basis. Substitutes are typically introduced to minimise/offset the effects of fatigue, alter tactics, replace players deemed as underperforming or injured, and/or give playing time to youth players or to squad members returning from injury. While the match-day practices of substitutes include participation in the pre-match warm-up, and sporadic periods of rewarm-up activity, it is currently unclear as to whether these pre-entry preparations facilitate optimal match performance thereafter. Acknowledging the contextual factors that possibly influence substitutes' performance, this review summarises the presently available literature on soccer substitutes, and makes recommendations for future research. Literature searching and screening yielded 13 studies, which have typically focused on characterising: (1) the patterns, including timing, of substitutes' introduction (2) indices of match-performance and (3) the emotional experiences of soccer substitutes. The majority of substitutions occur after the first-half has ended (i.e. at half-time or during the second-half), with introduced players exceeding the second-half physical performances of those who started the match. Observations of progressive improvements in running performance as playing time increases, and findings that substitutes mostly experience negative emotions, highlight the potential inadequacies of pre-match preparations, and present future research opportunities. Additional work is therefore needed to confirm these findings and to determine the efficacy of current preparation strategies, thereby providing opportunities to assess then address substitutes' pre-pitch entry preparations, on-field performance and emotional responses.
Publisher: Elsevier BV
Date: 08-2005
Abstract: Surface plasmon resonance (SPR) biosensor formats using gold nanoparticle or protein signal lification for the sensitive assay of small molecules were developed using progesterone as a model compound. Progesterone was immobilized to a dextran surface in the Biacore biosensor through in situ covalent immobilization using an oligoethylene glycol linker attached to the 4 position of the steroid. This surface produced stable antibody binding for in excess of 1100 assay cycles. Using this surface, assays were developed for progesterone using 10- and 20-nm gold-streptavidin labels attached to biotinylated monoclonal antibody in both label prebinding and sequential binding formats. Prelabeling formats gave no signal enhancement but produced assays with limits of detection of 143 pg/ml, compared with approximately 1 ng/ml in previous studies. Sequential binding formats gave signal enhancements of 2.2-fold over the monoclonal antibody and a limit of detection of 23.1 pg/ml. It was found that secondary antibody labeling gave 8.1-fold signal enhancements and a limit of detection of 20.1 pg/ml, whereas use of secondary antibody-25 nm gold complexes provided more signal enhancement (13-fold) and a further improvement in limit of detection of 8.6 pg/ml.
Publisher: Elsevier BV
Date: 2004
DOI: 10.1016/J.PHYSBEH.2003.10.014
Abstract: Pregnancy and lactation are accompanied by behavioral changes that include altered responses to stress. Previous exposure to a stressor can also modulate subsequent stress-related behavior, and this effect is at least partly mediated by the reproductive hormone, estrogen. In this study, we sought to determine if the stress-related behavior of rats that had been exposed to a cat would vary with reproductive status. After exposure to a cat or a nonstress control procedure, pregnant, lactating, virgin female or male rats received two acoustic startle test sessions on consecutive days, followed 4 days later by testing on an elevated plus maze. Startle litudes tended to increase across trials in all groups, but were differentially enhanced in nonstressed pregnant and lactating rats. A 5-min exposure to a cat eliminated the enhanced responding in these two groups. The cat exposure attenuated startle stimulus-evoked freezing only in the pregnant rats and produced differential plus maze performance in this group. Cat exposure produced no differential effects in virgin females or males. These results suggest that reproductive state can influence the impact of a stressor on subsequent behavior, but does so in a rather complex way.
Publisher: Canadian Science Publishing
Date: 06-2013
Abstract: Our purpose was to examine the effectiveness of carbohydrate and caffeine mouth rinses in enhancing repeated sprint ability. Previously, studies have shown that a carbohydrate mouth rinse (without ingestion) has beneficial effects on endurance performance that are related to changes in brain activity. Caffeine ingestion has also demonstrated positive effects on sprint performance. However, the effects of carbohydrate or caffeine mouth rinses on intermittent sprints have not been examined previously. Twelve males performed 5 × 6-s sprints interspersed with 24 s of active recovery on a cycle ergometer. Twenty-five milliliters of either a noncaloric placebo, a 6% glucose, or a 1.2% caffeine solution was rinsed in the mouth for 5 s prior to each sprint in a double-blinded and balanced cross-over design. Postexercise maximal heart rate and perceived exertion were recorded, along with power measures. A second experiment compared a combined caffeine-carbohydrate rinse with carbohydrate only. Compared with the placebo mouth rinse, carbohydrate substantially increased peak power in sprint 1 (22.1 ± 19.5 W Cohen's effect size (ES), 0.81), and both caffeine (26.9 ± 26.9 W ES, 0.71) and carbohydrate (39.1 ± 25.8 W ES, 1.08) improved mean power in sprint 1. Experiment 2 demonstrated that a combination of caffeine and carbohydrate improved sprint 1 power production compared with carbohydrate alone (36.0 ± 37.3 W ES, 0.81). We conclude that carbohydrate and (or) caffeine mouth rinses may rapidly enhance power production, which could have benefits for specific short sprint exercise performance. The ability of a mouth-rinse intervention to rapidly improve maximal exercise performance in the absence of fatigue suggests a central mechanism.
Publisher: Elsevier BV
Date: 1995
DOI: 10.1016/0309-1740(94)00043-7
Abstract: Effective electrical head-only stunning produces a seizure-like state followed by a period of analgesia seen in animals allowed to recover. Passing of a 1·0 A current (50 Hz, 500 V) for less than 0·2 s, through the head of a sheep does not produce a seizure-like state as evidenced by recorded electroencephalogram. Corresponding to this lack of seizure-like state, the release of the neurotransmitters glutamate and aspartate, in the brain, occurs to levels associated with arousal rather than seizure. At a duration of 0·2 s, the same stun parameters as above produce a seizure-like state and the release of glutamate and aspartate rises dramatically. The length of the seizure-like state, and the levels of release of glutamate, aspartate and a third neurotransmitter gamma amino-4-butyric acid (GABA), increased with stun duration until 4·0 s duration, where a peak in these parameters was seen. Stun durations of 2·0, 4·0, 8·0 and 12·0 s all produce similar effects. At a duration of 20 s, however, the length of the seizure-like state and the release of neurotransmitters is less than at shorter stun durations. For welfare purposes a head-only electrical stun, of 1·0 A, at a duration as low as 0·2 s produces unconsciousness and analgesia to subsequent slaughter procedures. However, maximum welfare benefits appear attainable at durations between 2·0 and 20·0 s.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 24-08-2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2005
DOI: 10.1249/01.MSS.0000177216.21847.8A
Abstract: Caffeine enhances performance of single bouts of endurance exercise, but its effects on repeated bouts typical of those in high-intensity team sports are unclear. To investigate effects of caffeine in a performance test simulating physical and skill demands of a rugby union game. The study was a double-blind, randomized, crossover design in which nine competitive male rugby players ingested either caffeine (6 mg.kg(-1) body mass) or placebo (dextrose) 70 min before performing a rugby test. Each test consisted of seven circuits in each of two 40-min halves with a 10-min half-time rest. Each circuit included stations for measurement of sprint time (two straight-line and three agility sprints), power generation in two consecutive drives, and accuracy for passing balls rapidly. Interstitial fluid was s led transdermally by electrosonophoresis before ingestion of caffeine or placebo and then before testing, at half-time, and immediately after testing s les were assayed chromatographically for caffeine and epinephrine concentrations. The effects of caffeine on mean performance (+/-90% confidence limits) over all 14 circuits were: sprint speeds, 0.5% (+/-1.7%) through 2.9% (+/-1.3%) first-drive power, 5.0% (+/-2.5%) second-drive power, -1.2% (+/-6.8%) and passing accuracy, 9.6% (+/-6.1%). The enhancements were mediated partly through a reduction of fatigue that developed throughout the test and partly by enhanced performance for some measures from the first circuit. Caffeine produced a 51% (+/-11%) increase in mean epinephrine concentration correlations between in idual changes in epinephrine concentration and changes in performance were mostly unclear, but there were some strong positive correlations with sprint speeds and a strong negative correlation with passing accuracy. Caffeine is likely to produce substantial enhancement of several aspects of high-intensity team-sport performance.
Publisher: Elsevier BV
Date: 05-2014
DOI: 10.1016/J.PHYSBEH.2014.04.001
Abstract: This study examined the social environment effects during a post-match video presentation on the hormonal responses and match performance in professional male rugby union players. The study participants (n=12) watched a 1-hour video of mixed content (player mistakes and successes) from a match played 1 day earlier in the presence of (1) strangers who were bigger (SB), (2) strangers who were smaller (SS), (3) friends who were bigger (FB) and (4) friends who were smaller (FS). The salivary testosterone (T) and cortisol (C) responses to a physical stress test were assessed 3 days later, along with pre-match T levels and match-ranked performance 6-7 days later. All treatments were associated with elevated T responses (% change from baseline) to the stress test with SS>SB and FB>FS. The C stress responses after the SS and SB interventions were both greater than FS and FB. On match-day, the FB approach was linked to higher T concentrations than SB and better ranked performance than FS and SS. The subsequent testing of a population sub-group (n=8) across a video (V) and a non-video (NV) presentation in a neutral social environment produced similar stress-test and performance outcomes, but pre-match T concentrations differed (V>NV). In conclusion, the presence of other males during a post-match video assessment had some influence on the hormonal responses of male athletes and match performance in the week that followed. Thus, the social environment during a post-match assessment could moderate performance and recovery in elite sport and, in a broader context, could be a possible modulator of human stress responses.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2013
Publisher: Springer Science and Business Media LLC
Date: 03-2012
DOI: 10.2165/11596850-000000000-00000
Abstract: Jet lag has potentially serious deleterious effects on performance in athletes following transmeridian travel, where time zones are crossed eastwards or westwards as such, travel causes specific effects related to desynchronization of the athlete's internal body clock or circadian clock. Athletes are particularly sensitive to the effects of jet lag, as many intrinsic aspects of sporting performance show a circadian rhythm, and optimum competitive results require all aspects of the athlete's mind and body to be working in tandem at their peak efficiency. International competition often requires transmeridian travel, and competition timings cannot be adjusted to suit in idual athletes. It is therefore in the interest of the in idual athlete and team to understand the effects of jet lag and the potential adaptation strategies that can be adopted. In this review, we describe the underlying genetic and physiological mechanisms controlling the circadian clock and its inherent ability to adapt to external conditions on a daily basis. We then examine the fundamentals of the various adaptation stimuli, such as light, chronobiotics (e.g. melatonin), exercise, and diet and meal timing, with particular emphasis on their suitability as strategies for competing athletes on the international circuit. These stimuli can be artificially manipulated to produce phase shifts in the circadian rhythm to promote adaptation in the optimum direction, but care must be taken to apply them at the correct time and dose, as the effects produced on the circadian rhythm follow a phase-response curve, with pronounced shifts in direction at different times. Light is the strongest realigning stimulus and careful timing of light exposure and avoidance can promote adjustment. Chronobiotics such as melatonin can also be used to realign the circadian clock but, as well as timing and dosage issues, there are also concerns as to its legal status in different countries and with the World Anti-Doping Agency. Experimental data concerning the effects of food intake and exercise timing on jet lag is limited to date in humans, and more research is required before firm guidelines can be stated. All these stimuli can also be used in pre-flight adaptation strategies to promote adjustment in the required direction, and implementation of these is described. In addition, the effects of in idual variability at the behavioural and genetic levels are also discussed, along with the current limitations in assessment of these factors, and we then put forward three case studies, as ex les of practical applications of these strategies, focusing on adaptations to travel involving competition in the Rugby Sevens World Cup and the 2016 Summer Olympics in Rio de Janeiro, Brazil. Finally, we provide a list of practice points for optimal adaptation of athletes to jet lag.
Publisher: Informa UK Limited
Date: 30-04-2016
DOI: 10.1080/02640414.2015.1040825
Abstract: We compared the effects of using passive-heat maintenance, explosive activity or a combination of both strategies during the post-warmup recovery time on physical performance. After a standardised warmup, 16 professional rugby union players, in a randomised design, completed a counter-movement jump (peak power output) before resting for 20 min and wearing normal-training attire (CON), wearing a passive heat maintenance (PHM) jacket, wearing normal attire and performing 3 × 5 CMJ (with a 20% body mass load) after 12 min of recovery (neuromuscular function, NMF), or combining PHM and NMF (COMB). After 20 min, participants completed further counter-movement jump and a repeated sprint protocol. Core temperature (Tcore) was measured at baseline, post-warmup and post-20 min. After 20 min of recovery, Tcore was significantly lower under CON and NMF, when compared with both PHM and COMB (P < 0.05) PHM and COMB were similar. Peak power output had declined from post-warmup under all conditions (P < 0.001) however, the drop was less in COMB versus all other conditions (P < 0.05). Repeated sprint performance was significantly better under COMB when compared to all other conditions. Combining PHM with NMF priming attenuates the post-warmup decline in Tcore and can positively influence physical performance in professional rugby union players.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.EARLHUMDEV.2015.04.011
Abstract: Digit ratio (2D:4D) is a marker for prenatal sex steroids and a correlate of sporting performance. This association may exist because low 2D:4D is linked to high prenatal levels of testosterone (T) and low oestrogens (E). It was recently suggested that low 2D:4D, and particularly low right-left 2D:4D (or Dr-l), is a marker for T changes in response to physical and aggressive challenges. If correct, this link may in part explain the association between 2D:4D and sports performance. We tested this hypothesis in adults. Three experimental treatments were completed using a randomised, cross-over design (i) cycle sprints plus an aggressive video (S+V), (ii) aggressive video plus cycle sprints (V+S), and (iii) a control session. 24 healthy adults (12 men and 12 women). Salivary T, oestradiol (E2) and cortisol (C) levels were measured on six occasions across each session and pooled for analysis. The S+V treatment was associated with a rise in T and C levels, and Dr-l was significantly and negatively correlated with T and E2 with these effects confined to men. The right 2D:4D and Dr-l were also negatively correlated with the T/C ratio and Dr-l negatively related to the E2/C ratio in men during the S+V treatment. We suggest that the hormonal responses to a challenge are programmed by prenatal levels of T and E with possible links to sporting performance in adulthood.
Publisher: Informa UK Limited
Date: 04-1999
DOI: 10.1080/00480169.1999.36113
Abstract: As kappa(kappa)-opioids have marked effects on pain threshold in sheep during oestrus, late pregnancy and after birth, a study was undertaken to determine if kappa -opioids also had other roles during these states. Opioid agonists (GR89696, DAMAGO) were administered into either the lateral hypothalamus (LH) or amygdala of non-pregnant sheep (n = 5) or pregnant sheep (n = 15) in late pregnancy (n = 5) within 12 h of birth (n = 5) or in the third week after birth (n = 5). Cortisol, behavioural and electrocardiographic responses to an auditory stimulus were assessed with and without drug administration, as was feed consumption and suckling events. In non-pregnant sheep, DAMAGO injected into either the LH or amygdala had little effect on the response to the auditory stimulus but when injected into the LH did decrease food consumption. GR 89696 had no obvious effects. In late pregnancy, cortisol and heart rate responses to the auditory stimulus were significantly reduced compared to the non-pregnant animals irrespective of treatment. This was also the case in the third week after birth. Immediately post-partum cortisol responses were closer to that seen in the non-pregnant animal. In late pregnancy and both post-partum periods, GR 89696 in the LH significantly increased feed consumption while DAMAGO had no significant effects. GR 89696 injected into the amygdala reduced the behavioural response to the auditory stimulus in late pregnancy and both post-partum periods. Changes in sensitivity to opioids occur in both the amygdala and LH with pregnancy and after birth. These may influence maternal behaviours and feed intake.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2010
Publisher: Informa UK Limited
Date: 08-01-1997
Publisher: Informa UK Limited
Date: 11-2010
DOI: 10.1080/02640414.2010.510143
Abstract: The relative length of the second and fourth digits (2D:4D) is a putative marker for prenatal testosterone. Low 2D:4D has been reported to correlate with high performance in sport in general. Here, for the first time, we examine the relationship between 2D:4D and performance in elite rugby players. The 44 players (28 forwards, 16 backs) were drawn from the Ospreys Rugby Union Club and 44 age-matched controls. The measures of performance comprised age-adjusted number of international performances (caps) for Wales, a comparison of coaches' first-choice League team with others, and the number of tries scored by backs in club matches. Compared with controls, players were larger and had lower 2D:4D for the right and left hand. With regard to number of caps, players with low 2D:4D in their right hand and low right 2D:4D compared with their left (right - left 2D:4D difference) had high numbers of caps. First-choice players did not differ significantly from second-choice players in their 2D:4D but they did have a lower right - left 2D:4D difference than second-choice players. Low right 2D:4D and low right - left 2D:4D difference were significantly linked with large numbers of tries. We conclude that low right 2D:4D and low right - left 2D:4D difference are predictors of high rugby performance.
Publisher: Informa UK Limited
Date: 19-08-2015
DOI: 10.1080/02701367.2015.1066927
Abstract: There is demand in applied sport settings to measure recovery briefly and accurately. Research indicates mood disturbance as the strongest psychological predictor of mental and physical recovery. The Brief Assessment of Mood (BAM) is a shortened version of the Profile of Mood States that can be completed in less than 30 s. The purpose of this study was to examine the BAM as a quick measure of mood in relation to recovery status in elite rugby players alongside established physiological markers of recovery. Using elite rugby union players (N = 12), this study examined the utility of BAM as an indicator of mental and physical recovery in elite athletes by exploring pattern change in mood disturbance, energy index, power output, cortisol, and testosterone 36 hr before and 12 hr, 36 hr, and 60 hr after a competitive rugby match. Repeated-measures multivariate analysis of variance indicated significant changes in all variables across the 4 time points (p < .05, η(2) range = .20-.48), concurrent with previous study findings. Although visual inspection of the graphs indicated that the pattern of change for mood disturbance and energy index mapped changes in all physiological variables, only a low correlation was observed for power output (r = - .34). Although BAM scores changed significantly over time in accordance with the hypotheses, further testing is required to confirm the utility of the BAM as a measure of recovery. The results indicate that the BAM could be used as 1 indicator of recovery status alongside other measures.
Publisher: Georg Thieme Verlag KG
Date: 29-06-2010
Publisher: Informa UK Limited
Date: 18-08-2015
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2013
Publisher: Georg Thieme Verlag KG
Date: 04-03-2011
Abstract: This study examined the validity of 2 kinematic systems for estimating force and power during squat jumps. 12 weight-trained males each performed single repetition squat jumps with a 20-kg, 40-kg, 60-kg and 80-kg load on a Kistler portable force plate. A commercial linear position transducer (Gymaware [GYM]) and accelerometer (Myotest® [MYO]) were attached to the bar to assess concentric peak force (PF) and peak power (PP). Across all loads tested, the GYM and MYO estimates of PF and PP were moderately to strongly correlated ( P≤0.05-0.001) with the force plate measurements ( R=0.59-0.87 and R=0.66-0.97), respectively. The mean PF and PP values were not significantly different between the 2 kinematic systems and the force plate, but the estimates did produce some systematic bias and relatively large random errors, especially with the 20-kg load (PF bias >170 N, PF error >335 N, PP bias >400 W, PP error >878 W). Some proportional bias was also identified. In summary, the estimation of PF and PP by a linear position transducer and accelerometer showed moderate to strong relative validity and equivalent absolute validity, but these estimates are limited by the presence of bias and large random errors.
Publisher: Elsevier BV
Date: 02-2004
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2016
DOI: 10.1519/JSC.0000000000000805
Abstract: Russell, M, Sparkes, W, Northeast, J, Cook, CJ, Love, TD, Bracken, RM, and Kilduff, LP. Changes in acceleration and deceleration capacity throughout professional soccer match-play. J Strength Cond Res 30(10): 2839–2844, 2016—As the acceleration and deceleration demands of soccer are currently not well understood, this study aimed to profile markers of acceleration and deceleration capacity during professional soccer match-play. This within-player observational study required reserve team players from a Premier League club to wear 10-Hz Global Positioning System units throughout competitive matches played in the 2013–14 competitive season. Data are presented for players who completed 4 or more games during the season ( n = 11), and variables are presented according to six 15-minute intervals (I1–6: 00:00–14:59 minutes, 15:00–29:59 minutes, 30:00–44:59 minutes, 45:00–59:59 minutes, 60:00–74:59 minutes, and 75:00–89:59 minutes, respectively). During I6, the distance covered (total, per minute, and at high intensity), number of sprints, accelerations (total and high intensity), decelerations (total and high intensity), and impacts were reduced compared with I1 (all p ≤ 0.05). The number of high-intensity impacts remained unchanged throughout match-play ( p 0.05). These findings indicate that high-intensity actions and markers of acceleration and deceleration capacity are reduced in the last 15 minutes of the normal duration of match-play. Such information can be used to increase the specificity of training programs designed for soccer players while also giving further insight in to the effects of 90 minutes of soccer-specific exercise. Interventions that seek to maintain the acceleration and deceleration capacity of players throughout the full duration of a soccer match warrant investigation.
Publisher: Informa UK Limited
Date: 06-03-2015
DOI: 10.1080/17461391.2015.1017012
Abstract: This study assessed the acute response of salivary testosterone and cortisol concentrations to four exercise protocols in 27 elite male rugby players. Each athlete completed four protocols in random order on separate in-season weeks. Two protocols were resistance training based consisting of four exercises (high pull, bench press, squat and chin-ups rone row): Protocol 1 consisted of 5 sets of 15 repetitions at 55% of 1 repetition maximum (1 RM) with 1-minute rest (5 × 15-55%). Protocol 2 consisted of three sets of five repetitions at 85% 1 RM with 2-minute rest (3 × 5-85%). Protocol 3 was a strongman (STRNG) session consisting of three stations within a circuit of exercises that included exercises such as battling ropes, prowler push, farmer's walk and tyre flips. Protocol 4 was based on boxing and wrestling inspired exercises (combative--COMB). Salivary testosterone and cortisol concentrations were measured before (PRE) and immediately after exercise (POST). Testosterone did not significantly change as a result of any intervention, whereas cortisol declined and the testosterone to cortisol (T/C) ratio increased significantly in both the 5 × 15-55% and 3 × 5-85% protocol. When results were retrospectively grouped and analysed according to the protocol that demonstrated the greatest absolute testosterone response, significant (P < 0.01) increases for the 5 × 15-55%, STRNG and COMB protocols were observed. The in idualised hormone response to exercise observed in this study highlights the importance of recognising a protocol-dependent approach to training athletes. Furthermore this study also highlights a potential usefulness of employing STRNG and COMB training protocols as an alternative stimulus to resistance training.
Publisher: Elsevier BV
Date: 04-2002
DOI: 10.1016/S0031-9384(02)00650-9
Abstract: In the hypothalamus, corticotropin-releasing hormone (CRH) has a well-described role initiating the hypothalamic-pituitary-adrenal (HPA) axis response to stress. Cortisol, released from the adrenal gland, exerts negative feedback on this axis. The role of extrahypothalamic CRH in stress responses is less well known. The purpose of this study was to measure the response of CRH in the amygdala to acute and repeated stress and to examine if cortisol had any effect on this response. Immunosensor-based microdialysis probes were used to measure CRH and cortisol in the amygdala and cortisol systemically in sheep exposed to a predator stress (a dog). Upon presentation of a dog, CRH increased in the amygdala of the sheep and then fell off. Cortisol levels rose both systemically and in the amygdala, and as they peaked, a second CRH response was observed. Repeated stress changed this response, with the magnitude of the first CRH peak decreasing while the second peak increased. Repeated stress also produced an exaggeration in both of the CRH peaks to presentation of a subsequent novel stress (a forelimb electric shock). Animals that had an escape route from the repeated dog stress did not show this exaggeration when faced subsequently with the novel stress. Administration of mifepristone, a glucocorticoid receptor antagonist, prior to the delivery of the repeat stress prevented subsequent changes in the CRH response. The data suggest that the amygdala shows a CRH response to presentation of a stressor acutely and repeatedly and that repeated stress can alter subsequent amygdala responsiveness to the same or a different stressor. This alteration appears dependent on circulatory glucocorticoids.
Publisher: BMJ
Date: 03-2006
Publisher: Informa UK Limited
Date: 03-2013
DOI: 10.1080/02640414.2012.747690
Abstract: There is evidence that the digit ratio (2D:4D) is a negative correlate of prenatal levels of testosterone, but there is no association between 2D:4D and the circulating levels of both total and free testosterone. Sports provide a physical challenge and participants often show increased levels of free testosterone immediately preceding and during competition. We tested this hypothesis of a link between 2D:4D and testosterone under challenge in 79 professional rugby players using the following procedures (i) 25 players were physically challenged using a repeated sprint agility test, and saliva s les were assayed for testosterone immediately preceding the repeated sprint agility test (time 1) and 5 minutes (time 2) and 20 minutes after completion of the repeated sprint ability (time 3) (ii) 54 players were also tested for salivary testosterone in an unchallenged condition. We found that right-left 2D:4D was significantly and negatively related to testosterone concentrations at times 1, 2 and 3 following the repeated sprint agility test (P < 0.05) and there was no association between the 2D:4D and basal testosterone levels in the unchallenged group. We suggest that low right-left 2D:4D is a predictive marker of free testosterone responsiveness when trained men are physically challenged, and that this association is programmed by the action of prenatal testosterone.
Publisher: Human Kinetics
Date: 09-2023
Abstract: Purpose : As the start of the 10th Rugby Union World Cup approaches, performance staff will be working on the final elements of their teams’ preparation. Much of this planning and preparation will be underpinned by the latest performance science research. In this invited commentary, we discuss contemporary performance science research in rugby union centered around 4 key performance domains. First, we outline a systematic approach to developing an overall understanding of the game demands and how performance staff can enhance the players’ preparedness for competition. We then move on to outline our understanding of the training science domain, followed by a brief overview of effective recovery strategies at major tournaments. Finally, we outline research in the area of competition-day strategies and how they can positively impact players’ readiness to compete. Conclusions : Evaluating a team’s preparation for the Rugby Union World Cup can be achieved by mapping their performance plan based on the 4 domains outlined above.
Publisher: Informa UK Limited
Date: 02-10-2018
Publisher: Elsevier BV
Date: 11-2013
Publisher: Informa UK Limited
Date: 08-01-1995
DOI: 10.1080/00480169.1995.35879
Abstract: The implications of shooting animals in the area of the occipito-atlantal junction was evaluated in three sheep by recording changes in the EEG activity. In one sheep, a shot which entered the occipito-atlantal junction and fractured the first cervical vertebra failed to produce insensibility. In contrast, a shot in another sheep which struck the occipital condyles of the skull resulted in loss of cortical evoked responses, the presence of high litude low frequency activity and ultimately all loss of brain activity. These results provide evidence that shooting through the vertebral column does not necessarily transmit sufficient percussive forces to higher brain regions to produce immediate insensibility. This has important implications for the humane destruction of animals, particularly, as in the case of cetaceans, where the occipito-atlantal junction or a high neck position is a recommended target area.
Publisher: Human Kinetics
Date: 03-2014
Abstract: To assess the measures of salivary free testosterone and cortisol concentrations across selected rugby union matches according to game outcome. Twenty-two professional male rugby union players were studied across 6 games (3 wins and 3 losses). Hormone s les were taken 40 min before the game and 15 min after. The hormonal data were grouped and compared against competition outcomes. These competition outcomes included wins and losses and a game-ranked performance score (1–6). Across the entire team, pregame testosterone concentrations were significantly higher during winning games than losses ( P = 5.8 × 10 −5 ). Analysis by playing position further revealed that, for the backs, pregame testosterone concentrations ( P = 3.6 × 10 −5 ) and the testosterone-to-cortisol ratio T:C ( P = .038) were significantly greater before a win than a loss. Game-ranked performance score correlated to the team’s pregame testosterone concentrations ( r = .81, P = .049). In backs, pregame testosterone ( r = .91, P = .011) and T:C ( r = .81, P = .05) also correlated to game-ranked performance. Analysis of the forwards’ hormone concentrations did not distinguish between game outcomes, nor did it correlate with game-ranked performance. Game venue (home vs away) only affected postgame concentrations of testosterone ( P = .018) and cortisol ( P = 2.58 × 10 −4 ). Monitoring game-day concentrations of salivary free testosterone may help identify competitive readiness in rugby union matches. The link between pregame T:C and rugby players in the back position suggests that monitoring weekly training loads and enhancing recovery modalities between games may also assist with favorable performance and outcome in rugby union matches.
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.EARLHUMDEV.2019.02.008
Abstract: The 2nd to 4th digit ratio (2D:4D) is regarded as a sexually dimorphic trait governed by prenatal testosterone (T) and estradiol exposure. However, relationships between the 2D:4D and adult sex hormone concentrations are inconsistent in females. Environmental contingencies (e.g., physical training) may provide a stronger basis for establishing these linkages, particularly if the relationships are plastic and not fixed. To investigate associations between 2D:4D, training hours and salivary T (sal-T) measures in physically-active women. Descriptive and quasi-experimental monitoring across the follicular (day 7), ovulatory (day 14) and luteal (day 21) phases of three menstrual cycles. 35 naturally-cycling women training regularly for sport (range 3-12 h a week). Morning sal-T concentrations and changes in sal-T to a physical and psychological stimulus (~10 min) were measured. Both 2D:4D and training hours were related to morning sal-T concentrations in all three menstrual phases (p < 0.01) and their interaction was significant during ovulation. Follow-up testing revealed a negative 2D:4D and sal-T association in women reporting high, but not low, training hours each week. Participant 2D:4D was also related to sal-T changes under physical and/or psychological challenge across each menstrual phase (p < 0.01), whereas training hours and its interaction with 2D:4D were not significant predictors of these outcomes. 2D:4D linkages with basal and challenge-induced sal-T changes were identified in women undertaking regular physical training. Training hours also moderated the 2D:4D link to morning sal-T, but with some menstrual-phase dependency. These complexities and environmental relationships may help reconcile conflicting results.
Publisher: Informa UK Limited
Date: 12-02-2015
DOI: 10.1080/17461391.2015.1010107
Abstract: The aim of this study was to determine the acute neuromuscular, biochemical and endocrine responses to a maximal speed training (MST) session. Eighteen male rugby players completed the protocol, which involved performing six maximal effort repetitions of 50 m running sprints with 5 minutes recovery between each sprint. Testosterone (T), cortisol (C), creatine kinase (CK), lactate (La), perceived muscle soreness (MS) and counter movement jump were collected immediately pre (PRE), immediately post (IP), 2 hours post (2P) and 24 hours post (24P) the sprint session. A bimodal recovery pattern was observed from the jump parameters with several declining significantly (p ≤ 0.05) IP, recovering 2P and suffering a secondary decline 24P. CK and perceived MS were elevated IP and continued to rise throughout the protocol, while La was only elevated IP. T and C were unaffected IP but showed significant declines 2P. These data indicate that MST results in a bimodal recovery pattern of neuromuscular function with changes most likely being related to metabolic and biochemical responses.
Publisher: Informa UK Limited
Date: 12-02-2015
DOI: 10.1080/17461391.2015.1010106
Abstract: This study assessed the positional and temporal movement patterns of professional rugby union players during competition using global positioning system (GPS) units. GPS data were collected from 33 professional rugby players from 13 matches throughout the 2012-2013 season s ling at 10 Hz. Players wore GPS units from which information on distances, velocities, accelerations, exertion index, player load, contacts, sprinting and repeated high-intensity efforts (RHIE) were derived. Data files from players who played over 60 min (n = 112) were separated into five positional groups (tight and loose forwards half, inside and outside backs) for match analysis. A further comparison of temporal changes in movement patterns was also performed using data files from those who played full games (n = 71). Significant positional differences were found for movement characteristics during performance (P < 0.05). Results demonstrate that inside and outside backs have greatest high-speed running demands however, RHIE and contact demands are greatest in loose forwards during match play. Temporal analysis of all players displayed significant differences in player load, cruising and striding between halves, with measures of low- and high-intensity movement and acceleration/deceleration significantly declining throughout each half. Our data demonstrate significant positional differences for a number of key movement variables which provide a greater understanding of positional requirements of performance. This in turn may be used to develop progressive position-specific drills that elicit specific adaptations and provide objective measures of preparedness. Knowledge of performance changes may be used when developing drills and should be considered when monitoring and evaluating performance.
Publisher: Springer Science and Business Media LLC
Date: 24-08-2018
DOI: 10.1007/S40279-018-0977-2
Abstract: Goalkeepers are typically the last defensive line for soccer teams aiming to minimise goals being conceded, with match rules permitting ball handling within a specific area. Goalkeepers are also involved in initiating some offensive plays, and typically remain in close proximity to the goal line while covering ~ 50% of the match distances of outfield players hence, the competitive and training demands of goalkeepers are unique to their specialised position. Indeed, isolated performance tests differentiate goalkeepers from outfield players in multiple variables. With a view to informing future research, this review summarised currently available literature reporting goalkeeper responses to: (1) match play (movement and skilled/technical demands) and (2) isolated performance assessments (strength, power, speed, aerobic capacity, joint range of motion). Literature searching and screening processes yielded 26 eligible records and highlighted that goalkeepers covered ~ 4-6 km on match day whilst spending ~ 98% of time at low-movement intensities. The most decisive moments are the 2-10 saves·match
Publisher: Elsevier BV
Date: 08-2014
Publisher: Informa UK Limited
Date: 03-06-2019
DOI: 10.1080/02640414.2019.1625613
Abstract: To examine responses to an International netball tournament, female athletes (
Publisher: BMJ
Date: 09-08-2016
DOI: 10.1136/BJSPORTS-2016-096191
Abstract: The loads to which professional rugby players are subjected has been identified as a concern by coaches, players and administrators. In November 2014, World Rugby commissioned an expert group to identify the physical demands and non-physical load issues associated with participation in professional rugby. To describe the current state of knowledge about the loads encountered by professional rugby players and the implications for their physical and mental health. The group defined 'load' as it relates to professional rugby players as the total stressors and demands applied to the players. In the 2013-2014 seasons, 40% of professional players appeared in 20 matches or more, and 5% of players appeared in 30 matches or more. Matches account for ∼5-11% of exposure to rugby-related activities (matches, team and in idual training sessions) during professional competitions. The match injury rate is about 27 times higher than that in training. The working group surmised that players entering a new level of play, players with unresolved previous injuries, players who are relatively older and players who are subjected to rapid increases in load are probably at increased risk of injury. A mix of 'objective' and 'subjective' measures in conjunction with effective communication among team staff and between staff and players was held to be the best approach to monitoring and managing player loads. While comprehensive monitoring holds promise for in idually addressing player loads, it brings with it ethical and legal responsibilities that rugby organisations need to address to ensure that players' personal information is adequately protected. Administrators, broadcasters, team owners, team staff and the players themselves have important roles in balancing the desire to have the 'best players' on the field with the ongoing health of players. In contrast, the coaching, fitness and medical staff exert significant control over the activities, duration and intensity of training sessions. If load is a major risk factor for injury, then managing training loads should be an important element in enabling players to perform in a fit state as often as possible.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JSAMS.2017.09.017
Abstract: To investigate the effect of oral contraceptive (OC) use on salivary testosterone (sal-T) concentrations and performance-related statistics in international field hockey matches. A cohort observational study with repeated measures. Twenty-three elite female athletes were monitored across four international field hockey matches over a nine-day period. Salivary T was assessed 45min before each match and several match performance statistics were collated load (i.e. ratings of perceived exertion×playing time), video-derived positive actions (PA) and negative actions (NA), plus coach and player ratings of performance. The sal-T and match performance profiles of OC (n=7) and Non-OC (n=16) players were compared and predictive relationships tested. Pre-match sal-T concentrations were 35% higher in the Non-OC than the OC group (p=0.001), representing a large effect size (ES) difference of 0.96. The OC and Non-OC groups did not differ on any performance statistic (p≥0.348) with ES differences from -0.22 to 0.11. Salivary T was positively related to the number of PA during match play (p=0.017). Additional linkage between sal-T and NA emerged, but with opposing slopes (p=0.008) in the OC (B=-1.783, p=0.030) and Non-OC (B=0.692, p=0.127) groups. OC usage by elite women athletes was accompanied by lower sal-T concentrations, but the performance outputs of the OC and Non-OC groups were similar. This suggests that the T differences had no impact on match performance. On an in idual (population-averaged) level, sal-T was associated with PA and NA during these matches, though the response curves predicting NA differed for OC and Non-OC athletes.
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.PHYSBEH.2012.05.009
Abstract: We examined the effect of different pre-match motivational interventions on athlete free testosterone (T) and cortisol (C) concentrations and subsequent match performance in professional rugby union. Male participants (n=12) playing at a senior or academy level in rugby union were recruited and each completed three interventions (15 min each) before a competitive game 1) watching a video clip of successful skill execution by the player with positive coach feedback [VPCF1] 2) watching a video clip of successful skill execution by an opposing player with cautionary coach feedback [VCCF], 3) the player left alone to self-motivate [SM1]. The first and last interventions were retested [VPCF2 and SM2]. Salivary free T and C measures were taken pre-intervention and pre-game. Within each game, players were rated by coaching staff on a key performance indicator (KPI) from identified skills and an overall performance indicator (OPI), where 1 = best performance to 5 = worst performance. The VPCF1 and VPCF2 interventions both promoted significant T responses (11.8% to 12.5%) before each game and more so than SM1, SM2 and VCCF. The VCCF approach produced the largest C response (17.6%) and this differed from all other treatments. The VPCF interventions were also associated with better game KPI (1.5 to 1.8) and OPI ratings (1.7 to 1.8) than SM1, SM2 and/or VCCF. Across all treatments, greater in idual T responses and lower C responses were associated with better KPI and OPI outcomes. In conclusion, the pre-game presentation of motivational strategies to athletes involving specific video footage and coach feedback produced different outcomes on two indicators of match performance, which were also associated with changes in free hormonal state.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2011
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.JSAMS.2012.11.889
Abstract: The pre-competition warm-up mediates many temperature related physiological changes which generally lead to an improvement in performance. However, after ceasing exercise body temperature declines rapidly, which reduces some of the benefits of the initial warm-up. We examined the effects of a passive heat maintenance strategy on post-warm-up core temperature (Tcore) and performance in professional rugby league players. Twenty professional rugby league players completed this randomised and counter-balanced study. After a standardised warm-up, players completed a countermovement jump (CMJ) before resting for 15min wearing normal training attire (control) or wearing a passive heat maintenance jacket (PHM), players then completed another CMJ and a repeated sprint protocol (RSA). Tcore was measured at baseline, post-warm-up, pre-RSA and post-RSA. CMJ were analysed for peak power output (PPO), and RSA for fastest, mean and total sprint time. Post-warm-up Tcore (mean±SD control 37.70±0.28 PHM 37.70±0.27°C p=0.741) and PPO (control 5220±353 vs. PHM 5213±331W p=0.686) were similar between conditions. At pre-RSA, PHM was associated with greater Tcore (control 37.14±0.31 vs. PHM 37.51±0.30°C p<0.001) and PPO (control 4868±345 vs. PHM 5056±344W p<0.001) when compared to control. The decline in PPO from post-warm-up to pre-RSA was related to the drop in Tcore (r=0.71 p<0.001). During the RSA, fastest, mean and total sprint time were all improved under PHM compared to control (p<0.05). Passive heat maintenance is an effective method of attenuating the post-warm-up decline in Tcore and improves PPO and repeated sprint ability in professional rugby league players.
Publisher: Public Library of Science (PLoS)
Date: 31-01-2019
Publisher: Public Library of Science (PLoS)
Date: 05-04-2018
Publisher: American Chemical Society (ACS)
Date: 22-12-2007
DOI: 10.1021/BC0602174
Abstract: Catecholamine derivatives were synthesized with potential applications as coating antigens in biosensors or in the raising of specific antibodies. Thioether-bridged derivatives of the catecholamines dopamine, norepinephrine, and epinephrine that attach carboxylic acid functionalities directly to the aromatic ring via an easily incremented linker chain were synthesized by an electrochemical method. These derivatives were purified by convenient ion-exchange chromatography, exact positions of conjugation determined by NMR, and a dopamine derivative immobilized in situ in a BIAcore surface plasmon resonance (SPR) biosensor and its antibody binding studied in comparison with immobilization via the catecholamine primary amine. Binding of an antibody raised to an amine-conjugated protein conjugate showed clear distinction between conjugations at different positions on the catecholamine, illustrating the importance of rational conjugate design in immunosensing of the catecholamines.
Publisher: Frontiers Media SA
Date: 03-08-2018
Publisher: Springer Science and Business Media LLC
Date: 19-01-2017
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 05-2018
DOI: 10.1016/J.PHYSBEH.2018.02.012
Abstract: There is evidence linking women's testosterone (T) to competitive behaviours in sport and exercise. To advance this work, we examined the longitudinal relationships between salivary T (sal-T) and competitiveness in athletic women who differ in training status. Elite (n = 9) and non-elite (n = 21) women athletes were monitored on days 6-8 (follicular phase), 13-15 (ovulatory phase) and 20-22 (Luteal phase) of a menstrual cycle with two repeats. Salivary T levels were assessed before breakfast, followed by two questions (each rated on a 1-7 scale) on competitive desire and training motivation. Using a linear mixed model, we evaluated the menstrual phase and training status effects on each variable, before assessing the within-subject effects of sal-T on competitiveness. Salivary T concentrations were higher at ovulation (effect size [ES] difference = 0.2-1.4), relative to the follicular and luteal phases, with a more marked response among elite women (p < .01). The competitiveness ratings showed similar menstrual-phase variation (ES difference = 0.6-1.0 at ovulation). A positive effect of sal-T on competitiveness emerged in both groups (p < .001), but with different slope patterns (p < .015). Specifically, the elite sal-T relationships with desire to compete (standardized β = 1.147, SE = 0.132) and training motivation (β = 1.195, SE = 0.124) were stronger compared with non-elite women (β = 0.631, SE = 0.114 β = 0.778, SE = 0.114), respectively. Morning sal-T concentrations, competitive desire and training motivation all peaked around ovulation in women athletes. Notably, sal-T availability and its relationship with competitiveness was stronger among high-performing athletes. Our findings confirm menstrual fluctuations in T and competitiveness among naturally-cycling women, with population context as a moderating factor.
Publisher: Informa UK Limited
Date: 26-02-2017
Publisher: Informa UK Limited
Date: 03-2008
DOI: 10.1080/02640410701552872
Abstract: The aim of this study was to determine the magnitude and pattern of intensity, and physiological strain, of competitive exercise performed across several days, as in adventure racing. Data were obtained from three teams of four athletes (7 males, 5 females mean age 36 years, s = 11 cycling .VO(2 peak) 53.9 ml . kg(-1) . min(-1), s = 6.3) in an international race (2003 Southern Traverse 96 - 116 h). Heart rates (HR) averaged 64% (95% confidence interval: +/- 4%) of heart rate range [%HRR = (HR - HR(min))/(HR(max) - HR(min)) x 100] during the first 12 h of racing, fell to 41% (+/-4%) by 24 h, and remained so thereafter. The level and pattern of heart rate were similar across teams, despite one leading and one trailing all other teams. Core temperature remained between 36.0 and 39.2 degrees C despite widely varying thermal stress. Venous s les, obtained before, during, and after the race, revealed increased neutrophil, monocyte and lymphocyte concentrations (P < 0.01), and increased plasma volume (25 +/- 10% P < 0.01) with a stable sodium concentration. Standardized exercise tests, performed pre and post race, showed little change in the heart rate-work rate relationship (P = 0.53), but a higher perception of effort post race (P < 0.01). These results provide the first comprehensive report of physiological strain associated with adventure racing.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 29-04-2020
DOI: 10.1249/MSS.0000000000002397
Abstract: This study aimed to examine the link between stress (measured via salivary cortisol and testosterone), cognition (measured via pupillometry, with greater pupil constriction and reduced pupil constriction latency associated with increased attention and improved information processing), and motor skill capacity (measured via somatosensory processing). Twenty-five professional rugby players participated in this study. Saliva s les were collected upon waking, before pupillometry and somatosensory processing testing, and after testing. Testing times varied for participants however, it was always in the morning, and the order of testing was randomized. Very small differences in hormone concentrations were seen across the morning (effect size = 0.01). Moderate to large differences in left eye pupil constriction for direct (left eye) versus consensual (right eye) stimulus were also seen ( P 0.01 effect size = 0.51 to 1.04). No differences for pupil constriction latency were seen for direct versus consensual stimulus. Some positive weak to moderate relationships were seen for testosterone and pupil constriction latency ( r = 0.37 to 0.39, P 0.05). Moderate to strong inverse relationships were seen for hormones with left eye pupil constriction difference between direct and consensual stimulus, and for pre- to posttest testosterone-to-cortisol ratio decline with left eye pupil constriction for direct and consensual stimulus ( r = 0.41 to 0.52, P 0.05). Weak to moderate inverse relationships for testosterone-to-cortisol ratio decline and somatosensory processing were seen ( r = 0.36 to 0.47, P 0.05). Stress may affect ability to receive information and ability to execute motor tasks. Thus, stress may compromise ability to make appropriate objective decisions and consequently execute skill/task behavior. Strategies to help mitigate negative stress responses are noted.
Publisher: Springer Science and Business Media LLC
Date: 26-06-2016
Abstract: To address the rapid influence of testosterone (T) on neuromuscular performance, we compared the T and physical performance responses of adults exposed to a physical and psychological stimulus. A group of healthy men (n=12) and women (n=14) each completed three treatments using a randomised, crossover design: exercise involving five × ten-second cycle sprints, viewing a video clip with aggressive content and a control session. Salivary T concentrations, hand-grip strength (HGS) and countermovement jump peak power (CMJ PP) were assessed before and 15 minutes after each session. The relative changes in T (17±29%) and CMJ PP (-0.1±4.4%) following sprint exercise were superior to the aggressive video (-6.3±19%, -2.2±5.9%) and control (-4.8±23%, -2.8±4.4%) treatments, respectively (p ≤0.05). Pre-treatment T levels correlated (r= -0.58 to -0.61, p <0.05) with the T responses of men (sprint exercise) and women (sprint exercise, aggressive video), but no variables were significantly correlated with the relative changes in HGS or CMJ PP. Sprint exercise promoted a general rise in T and maintained CMJ PP, relative to the video and control treatments. In both sexes, those in iduals with higher pre-test T levels tended to produce smaller T responses to one or more treatments. These data highlight the importance of stimulus selection and in idual predispositions when attempting to acutely modify T and associated physical performance.
Publisher: Elsevier BV
Date: 05-2001
Publisher: Springer Science and Business Media LLC
Date: 09-09-2014
DOI: 10.1007/S40618-014-0144-Z
Abstract: The testosterone (T) responses to a physical stimulus are thought to be more stable and reproducible compared to a psychological stimulus. This study compared the salivary T (Sal-T) responses to both stimuli in four groups of men: professional rugby players (n = 17), recreational rugby players (n = 10), a mixed athlete group (n = 14) and untrained controls (n = 12). Each group completed three treatments: (1) watching a video with aggressive rugby footage, (2) performing a short bout of sprint exercise and (3) a control session. Saliva s les were taken before and 15 min after each treatment. The sprint exercise changes in Sal-T levels were similar in the elite rugby (17.1 ± 11.1%), recreational rugby (11.9 ± 15.9%), mixed athlete (27.6 ± 32.0%) and control groups (25.3 ± 23.6%). In response to the video, Sal-T increased in the elite rugby (6.9 ± 6.4%) and untrained groups (11.9 ± 13.5%), but decreased in the recreational rugby players (-7.5 ± 11.0%). The in idual Sal-T responses to the sprints were also correlated (r = 0.69 to 0.82) with other treatment responses. Sprint exercise had a more consistent effect on Sal-T than a video with aggressive content and thus, could provide a reliable stimulus for increasing T availability in men with different training backgrounds. In idual Sal-T reactivity also appears to be somewhat stable across different treatments. These data provide further understanding around the induction, moderation and interpretation of T physiology.
Publisher: Human Kinetics
Date: 09-2023
Abstract: Purpose : The efficacy of isolated and relative performance indicators (PIs) has been compared in rugby union the latter more effective at discerning match outcomes. However, this methodology has not been applied in women’s rugby. The aim of this study was to identify PIs that maximize prediction accuracy of match outcome, from isolated and relative data sets, in women’s rugby union. Methods : Twenty-six PIs were selected from 110 women’s international rugby matches between 2017 and 2022 to form an isolated data set, with relative data sets determined by subtracting corresponding opposition PIs. Random forest classification was completed on both data sets, and feature selection and importance were used to simplify models and interpret key PIs. Models were used in prediction on the 2021 World Cup to evaluate performance on unseen data. Results : The isolated full model correctly classified 75% of outcomes (CI, 65%–82%), whereas the relative full model correctly classified 78% (CI, 69%–86%). Reduced respective models correctly classified 74% (CI, 65%–82%) and 76% (CI, 67%–84%). Reduced models correctly predicted 100% and 96% of outcomes for isolated and relative test data sets, respectively. No significant difference in accuracy was found between data sets. In the relative reduced model, meters made, clean breaks, missed tackles, lineouts lost, carries, and kicks from hand were significant. Conclusions : Increased relative meters made, clean breaks, carries, and kicks from hand and decreased relative missed tackles and lineouts lost were associated with success. This information can be utilized to inform physical and tactical preparation and direct physiological studies in women’s rugby.
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/WR00076
Abstract: A lure is needed for cost-effective control of feral goat populations dispersed in forests. We evaluated the odour delta-decanolactone and the pheromone (Z)-7-dodecen-1-yl acetate in a series of trials using penned Angora goats on two New Zealand farms. Filter paper discs at each of two feeders stocked with lucerne chaff dispensed 2 mL of odour or pheromone in solution. The goats could also forage for grass. We counted goats at each feeder at 30-min intervals, and analysed how often the number at one exceeded the other. Delta-decanolactone attracted female goats significantly more often than the control solution (5% ethanol) in 1 of 3 trials and was not attractive when it was combined with oxytocin and gamma-amino-n-butyric acid in 1 trial. (Z)-7-dodecen-1-yl acetate was significantly more attractive than the control in 1 of 2 trials on females and 2 of 3 trials on males, but addition of oxytocin and gamma-amino-n-butyric acid did not enhance the effect. A mixture of the odour and the pheromone attracted females in 1 of 3 trials. Inconsistent results between similar trials indicate the substances tested were unlikely to be universally attractive under field conditions.
Publisher: Human Kinetics
Date: 09-2023
Abstract: Purpose : To explore complex system behavior and subsequent team performance in professional rugby union. Methods : Here, we present 2 studies. In the first, we used global positioning system technology to measure player clustering during stoppages in play in nearly 100 games of professional rugby union to explore team (complex system) behavior and performance. In the second, we measured stress hormones (cortisol and testosterone) prior to team meetings and analyzed these relative to amount of time and the frequency with which players looked at peer presenters, as well as subsequent training performance, to explain how stress may lead to behaviors observed in the first study and subsequent match performance. Results : No link between player clustering during stoppages of play and performance was observed. When players (complex system agents) demonstrated greater levels of stress (as indicated by greater cortisol-awakening response and a greater decline in testosterone-to-cortisol ratio across the morning), they tended to look at peer presenters more however, training quality declined ( P = .02). Correlational analysis also showed that training quality was related to testosterone-to-cortisol ratio ( P = .04). Conclusions : Team behavior is complex and can be unpredictable. It is possible that under stress, complex system agents (ie, rugby union players) look at (and cluster toward) their teammates more however, meaningful interaction may not necessarily occur. Furthermore, while complex system (team) analysis may be valuable strategically in rugby union in the context of describing behavior, without understanding “how” or “why” intrateam/interagent behaviors emerge it may have little meaning.
Publisher: Human Kinetics
Date: 09-2023
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2015
Publisher: Emerald
Date: 06-11-2020
Abstract: Team effectiveness is often predicated by a group’s ability to communicate. However, the effect of stress response on communication success, particularly nonverbal engagement, and how this might affect team performance, is not clear a “phenomenon” this study sought to explore. This was an observational study in a cohort of professional rugby players. Participants gave presentations to their peers on two separate occasions during a “live-in” c designed to have psychologically stressful elements. Presentations were video recorded and audience engagement was measured. Testosterone and cortisol were used as biomarkers of stress response, with a high testosterone–cortisol ratio considered positive. A team training session followed the presentations and participants were rated for training quality. A small decline in testosterone was observed each day after waking. Conversely, cortisol rose after waking, with the rise being the highest on the first day. A decline in testosterone–cortisol ratio was also seen each day after waking the decline was greatest on the first day. Presentation duration and audience engagement was greatest for the second presentation when the testosterone-cortisol ratio decline and the cortisol increase after waking was smaller. Training quality was also better that day. Pooled data revealed a moderate inverse relationship and weak positive relationships for audience engagement with post-meeting cortisol and post-meeting testosterone–cortisol ratio, respectively. Training quality was related to testosterone and testosterone–cortisol ratio, but inversely related to cortisol. This study suggests that in stressful conditions, as suggested by an awakening hormone response, communication and team performance could become compromised with reduced ability to engage with others.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2016
DOI: 10.1519/JSC.0000000000001423
Abstract: Johnston, MJ, Cook, CJ, Drake, D, Costley, L, Johnston, JP, and Kilduff, LP. The neuromuscular, biochemical, and endocrine responses to a single-session vs. double-session training day in elite athletes. J Strength Cond Res 30(11): 3098–3106, 2016—The aim of this study was to compare the acute neuromuscular, biochemical, and endocrine responses of a training day consisting of a speed session only with performing a speed-and-weights training session on the same day. Fifteen men who were academy-level rugby players completed 2 protocols in a randomized order. The speed-only protocol involved performing 6 maximal effort repetitions of 50-m running sprints with 5 minutes of recovery between each sprint, whereas the speed-and-weights protocol involved the same sprinting session but was followed 2 hours later by a lower-body weights session consisting of 4 sets of 5 backsquats and Romanian deadlift at 85% one repetition maximum. Testosterone, cortisol, creatine kinase, lactate, and perceived muscle soreness were determined immediately before, immediately after, 2 hours after, and 24 hours after both the protocols. Peak power, relative peak power, jump height, and average rate of force development were determined from a countermovement jump (CMJ) at the same time points. After 24-hours, muscle soreness was significantly higher after the speed-and-weights protocol compared with the speed-only protocol (effect size η 2 = 0.253, F = 4.750, p ≤ 0.05). There was no significant difference between any of the CMJ variables at any of the posttraining time points. Likewise, creatine kinase, testosterone, and cortisol were unaffected by the addition of a weight-training session. These data indicate that the addition of a weight-training session 2 hours after a speed session, whereas increasing the perception of fatigue the next day does not result in a difference in endocrine response or in neuromuscular capability.
Publisher: American Physiological Society
Date: 03-2016
DOI: 10.1152/PHYSIOLGENOMICS.00107.2015
Abstract: We aimed to quantify the ACE I/D and ACTN3 R577X (rs1815739) genetic variants in elite rugby athletes (rugby union and league) and compare genotype frequencies to controls and between playing positions. The rugby athlete cohort consisted of 507 Caucasian men, including 431 rugby union athletes that for some analyses were ided into backs and forwards and into specific positional groups: front five, back row, half backs, centers, and back three. Controls were 710 Caucasian men and women. Real-time PCR of genomic DNA was used to determine genotypes using TaqMan probes and groups were compared using χ 2 and odds ratio (OR) statistics. Correction of P values for multiple comparisons was according to Benjamini-Hochberg. There was no difference in ACE I/D genotype between groups. ACTN3 XX genotype tended to be underrepresented in rugby union backs (15.7%) compared with forwards (24.8%, P = 0.06). Interestingly, the 69 back three players (wings and full backs) in rugby union included only six XX genotype in iduals (8.7%), with the R allele more common in the back three (68.8%) than controls (58.0% χ 2 = 6.672, P = 0.04 OR = 1.60) and forwards (47.5% χ 2 = 11.768, P = 0.01 OR = 2.00). Association of ACTN3 R577X with playing position in elite rugby union athletes suggests inherited fatigue resistance is more prevalent in forwards, while inherited sprint ability is more prevalent in backs, especially wings and full backs. These results also demonstrate the advantage of focusing genetic studies on a large cohort within a single sport, especially when intrasport positional differences exist, instead of combining several sports with varied demands and athlete characteristics.
Publisher: Informa UK Limited
Date: 23-12-2020
Publisher: Index Copernicus
Date: 03-05-2016
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.EARLHUMDEV.2019.104843
Abstract: Testosterone (T) is taken or prescribed to enhance appearance, increase athletic performance and libido and to treat hypogonadism. Digit ratio (2D:4D) is thought to be a negative correlate of prenatal T. Here we consider the relationship between 2D:4D and T supplementation. Our s le was taken from the BBC internet study. Respondents were asked (y/n) if they were taking (i) T, (ii) hormone replacement therapy with T (HRTwT). We removed extreme 2D:4D values and age and considered the most numerous ethnic group (i.e. "Whites"). Analyses were performed with a two-factor (sex*T) analysis of variance with covariate age and dependent variables 2D:4D or right-left 2D:4D (Dr-l). Out of 197,589 respondents, 793 (598 males) reported taking T. There was a significant main effect for right 2D:4D such that T supplementing males had higher 2D:4D than those who did not. The sex*T interaction was significant, but the effect reversed in females. There were 22,576 (661 males) participants who reported taking HRTwT. We found a significant main effect for right 2D:4D, males taking HRTwT had higher 2D:4D than those who did not. This was reversed in females. The sex*HRTwT interaction was significant, a high Dr-l was also found in males reporting HRTwT. Males who reported taking T or HRTwT had high right 2D:4D and/or Dr-l. The situation with females may be the reverse of that found in males but effect sizes are less. The health implications of an association between high (feminized) 2D:4D and T supplementation in males are discussed.
Publisher: Elsevier BV
Date: 03-2018
DOI: 10.1016/J.JSAMS.2017.05.021
Abstract: Evidence suggests that stress-induced changes in testosterone and cortisol are related to future competitive behaviours and team-sport outcomes. Therefore, we examined whether salivary testosterone and cortisol reactivity to a mid-week stress test can discriminate a match outcome in international rugby union competition. Single group, quasi-experimental design with repeated measures. Thirty-three male rugby players completed a standardised stress test three or four days before seven international matches. Stress testing involved seven minutes of shuttle runs (2×20m), dispersed across one-minute stages with increasing speeds. Salivary testosterone and cortisol were measured in the morning, along with delta changes from morning to pre-test (Morn-PreΔ) and pre-test to post-test (Pre-PostΔ). Data were compared across wins (n=3) and losses (n=4). The Morn-PreΔ in cortisol increased before winning and decreased prior to losing (p<0.001), with a large effect size difference (d=1.6, 90% CI 1.3-1.9). Testosterone decreased significantly across the same period, irrespective of the match outcome. The Morn-PreΔ in testosterone and cortisol, plus the Pre-PostΔ in testosterone, all predicted a match outcome (p≤0.01). The final model showed good diagnostic accuracy (72%) with cortisol as the main contributor. The salivary testosterone and cortisol responses to mid-week testing showed an ability to discriminate a rugby match outcome over a limited number of games. The Morn-PreΔ in cortisol was the strongest diagnostic biomarker. This model may provide a unique format to assess team readiness or recovery between competitions, especially with the emergence of rapid hormonal testing.
Publisher: Elsevier BV
Date: 09-2004
Publisher: Human Kinetics
Date: 11-2021
Abstract: Purpose : To establish if training volume was associated with androgen baselines and androgen responsiveness to acute exercise. Methods : During a “high-volume” training phase, 28 cyclists (14 men and 14 women) undertook oxygen-uptake and maximal-work-capacity testing. Two days later, they completed a repeat-sprint protocol, which was repeated 3 weeks later during a “low-volume” phase. Blood and saliva s les were collected before and after (+5 and +60 min) the repeat-sprint protocol. Blood was assayed for total testosterone (TT), free testosterone (FT), and dihydrotestosterone (DHT) and saliva, for testosterone and DHT. Results : Pretrial TT, FT, and DHT concentration was greater for males ( P .001, large effect size differences), and in both genders TT, DHT, and saliva for DHT was higher during high-volume loading (moderate to large effect size). Area-under-the-curve analysis revealed larger TT, FT, and DHT responses to the repeat-sprint protocol among females, and high-volume training was linked to larger TT, DHT, and saliva for DHT responses (moderate to large effect size). Baseline TT and FT correlated with oxygen uptake and work capacity in both genders ( P .05). Conclusion : DHT showed no acute performance correlation but was responsive to volume of training, particularly in females. This work informs on timelines and relationships of androgenic biomarkers in males and females across different training loads, adding to the complexity that should be considered in interpretation thereof. The authors speculate that testosterone may impact acute performance via behavioral mechanisms of motivation and attention DHT, via training volume-induced androgenic promotion, may facilitate long-term adaptive changes, especially for females.
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.STEROIDS.2006.03.004
Abstract: Thioether-linked 3-mercaptopropionic acid derivatives of 17beta-estradiol and estrone were formed at the A-ring 4-position of the steroids by substitution of their 4-bromo analogues. The carboxylic acid terminal was used to link to an oligoethylene glycol (OEG) chain of 15-atoms in length. The OEG derivative of 17beta-estradiol was then in situ immobilized on a carboxymethylated dextran-coated gold sensor surface used to detect refractive index changes upon protein binding to the surface by surface plasmon propagation in a BIAcore surface plasmon resonance (SPR) instrument. Two other estradiol-OEG derivatives with Mannich reaction linkage at the 2-position and hemisuccinate linkage at the 3-position were also immobilized on the sensor surfaces for comparison. Binding performance between these immobilized different positional conjugates and monoclonal anti-estradiol antibody, raised from a 6-position conjugate, clearly demonstrated that both 2- and 4-conjugates, not conjugated through existing functional groups, gave strong antibody bindings, whereas the 3-conjugate through an existing functional group (3-OH) gave very little binding (2% compared to the 2-conjugate). Both 2- and 4-position conjugates were then applied in a highly sensitive estradiol SPR immunoassay with secondary antibody mediated signal enhancement that gave up to a 9.5-fold signal enhancement of primary antibody binding, and a detection limit of 25 pg/mL was achieved for a rapid and convenient flow-through immunoassay of estradiol.
Publisher: Informa UK Limited
Date: 04-02-2011
Publisher: Human Kinetics
Date: 09-2023
Abstract: Purpose: Mental rehearsal is commonly employed, with positive visualization proposed to enhance complex skill performance. Additionally, video stimulus has been associated with enhanced kinesthetic sensations and rapid hormone fluctuations that may contribute to enhancing mental rehearsal and the conscious and unconscious emotional state for skill execution. Here, we assessed the impact of a 15-minute mental rehearsal intervention on rugby-specific tasks and the associated hormone profile. Methods: Professional rugby players (N = 10) volunteered for a randomized crossover study. They completed three 15-minute preparatory phases (positive or negative video-guided mental rehearsal or self-directed mental rehearsal alone) prior to an exercise stressor and rugby-specific passing task. Salivary testosterone and cortisol were monitored to assess stress responses. Results: Performance during the rugby passing task was improved following the positive video condition (91% [7.4%]) compared to the negative video (79% [6.0%] ES: 1.22 ± 0.75) and self-visualization (86% [5.8%] ES: 0.58 ± 0.75), with a significant correlation observed between passing performance and salivary testosterone ( r = .47 ± .34, P = .0087). Positive video imagery prior to an exercise stressor also significantly enhanced physiological stress resilience ( r = .39 ± .36, P = .0352). Conclusions: This pilot study demonstrates that mental rehearsal was enhanced by appropriate, context-specific video presentation. We propose that the interaction between sex steroids, the adrenal axis, and subsequent conscious and unconscious behaviors may be relevant to competitive rugby. Specifically, we suggest that relatively elevated free testosterone imparts a degree of stress resilience, which may lead to enhanced expression of competitive behaviors and provide an enhanced state for rugby skill execution.
Publisher: Springer Science and Business Media LLC
Date: 26-05-2021
DOI: 10.1007/S10072-021-05335-7
Abstract: Studies indicate that high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) can lower cortisol concentration or output, with some evidence suggesting a link to testosterone. Together, these stress and social hormones might help regulate the emotional response to HF-rTMS. This pilot study evaluated the effect of HF-rTMS on acute testosterone and cortisol dynamics and emotional state in eleven healthy adults. Using a sham-controlled, single-blind, crossover design, participants completed a HF-rTMS session targeting the dorsolateral prefrontal cortex (DLPFC) and motor cortex on separate days. Stimulation (250 total pulses) was applied at 90% of the resting motor threshold. Salivary testosterone and cortisol, mood, motivation, anxiety, and heart rate (HR) were assessed before (T
Publisher: Elsevier BV
Date: 09-2001
DOI: 10.1016/S0165-0270(01)00421-6
Abstract: A method is described for the measurement of cortisol or corticotropin-releasing hormone (CRH) from the brain, within, or in the dialysate of, a microdialysis probe using an antibody-linked assay. Polyclonal antibodies for either cortisol or CRH provide a specificity of measurement. These antibodies are affixed on a platinum electrode within the probe. Determination of bound cortisol or CRH is performed via an indirect assessment of competitive ligand also bound, and conjugated to HRP. This is activated and measured as current change. These probes were used for extracellular measurements in the amygdala, a limbic brain region, of sheep. Direct measurement in vivo compared favorably to the use of either the immunosensor or standard RIA techniques on dialysate emerging from a classical microdialysis probe, suggesting that the method could be used directly in-vivo. This is the first report in literature of rapid on-line measurement of CRH and cortisol from a discrete brain area. The probes have fast response times (>90% of maximum response within 30 s of start of analysis), high sensitivity ( 72 h) and regenerable, offering on-line measurement, with rapid time resolution, of neurohumoral substances.
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.JSAMS.2017.06.005
Abstract: In thermoneutral conditions, half-time is associated with reductions in body temperature that acutely impair performance. This laboratory-based study compared active, passive, and combined methods of half-time heat maintenance. Randomised, counterbalanced, cross-over. After a standardised warm-up (WU) and 15min of rest, professional Rugby Union players (n=20) completed a repeated sprint test (RSSA1). Throughout a simulated half-time (temperature: 20.5±0.3°C humidity: 53±5%), players then rested (Control) or wore a survival jacket (Passive) for 15min, or performed a 7min rewarm-up after either 8min of rest (Active), or 8min of wearing a survival jacket (Combined). A second RSSA (RSSA2) followed. Core temperature (T All half-time interventions attenuated reductions in T While the efficacy of passive and active heat maintenance methods was supported throughout a simulated half-time, a combined approach to attenuating heat losses appeared the most beneficial for T
Publisher: BMJ
Date: 04-01-2013
DOI: 10.1136/BJSPORTS-2012-091647
Abstract: Training recovery is vital for adaptation and performance, and to avoid cumulative fatigue and symptoms associated with overtraining. The use of cold-water immersion (CWI) as a recovery strategy is common however, the physiological and biochemical rationale behind its use remains unclear. This study aimed to assess the relationship between body temperature responses to water immersion and in idual perception of recovery, with subsequent exercise performance. Twelve male rugby players participated in a 3-week cross-over trial where an intense 60 min conditioning session was followed immediately by 15 min of either 14°C CWI, 30°C warm-water immersion (WWI) or passive control (CON) recovery intervention. Postexercise body temperatures and subjective ratings of the recovery intervention were recorded and subsequently related to performance in a 5×40 m repeated sprint protocol undertaken 24 h later. CWI induced large reductions in core body temperature postimmersion (effect size (ES) range 1.05-3.21) and improved subsequent sprint performance compared to WWI (ES 1.04±0.84) and CON (ES 1.44±0.84). Both the degree of temperature decrease at 60 min postimmersion (r=0.6948 p=0.0121) and the subjective rating of the recovery intervention (r=0.5886 p=0.0441) were related to subsequent sprint performance. A very strong linear correlation was observed when these two factors were integrated (r=0.7743 p=0.0031). A combination of physiological and psychological indices provides an improved indication of subsequent performance and suggests an important role of in idual perception in enhancing training recovery.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2012
Publisher: Springer Science and Business Media LLC
Date: 02-2011
DOI: 10.2165/11539170-000000000-00000
Abstract: The aim of this review is to highlight two emerging concepts for the elite athlete using the resistance-training model: (i) the short-term effects of testosterone (T) and cortisol (C) on the neuromuscular system and (ii) the dose-response training role of these endogenous hormones. Exogenous evidence confirms that T and C can regulate long-term changes in muscle growth and performance, especially with resistance training. This evidence also confirms that changes in T or C concentrations can moderate or support neuromuscular performance through various short-term mechanisms (e.g. second messengers, lipid rotein pathways, neuronal activity, behaviour, cognition, motor-system function, muscle properties and energy metabolism). The possibility of dual T and C effects on the neuromuscular system offers a new paradigm for understanding resistance-training performance and adaptations. Endogenous evidence supports the short-term T and C effects on human performance. Several factors (e.g. workout design, nutrition, genetics, training status and type) can acutely modify T and/or C concentrations and thereby potentially influence resistance-training performance and the adaptive outcomes. This novel short-term pathway appears to be more prominent in athletes (vs non-athletes), possibly due to the training of the neuromuscular and endocrine systems. However, the exact contribution of these endogenous hormones to the training process is still unclear. Research also confirms a dose-response training role for basal changes in endogenous T and C, again, especially for elite athletes. Although full proof within the physiological range is lacking, this athlete model reconciles a proposed permissive role for endogenous hormones in untrained in iduals. It is also clear that the steroid receptors (cell bound) mediate target tissue effects by adapting to exercise and training, but the response patterns of the membrane-bound receptors remain highly speculative. This information provides a new perspective for examining, interpreting and utilizing T and C within the elite sporting environment. For ex le, in idual hormonal data may be used to better prescribe resistance exercise and training programmes or to assess the trainability of elite athletes. Possible strategies for acutely modifying the hormonal milieu and, thereafter, the performance/training outcomes were also identified (see above). The limitations and challenges associated with the analysis and interpretation of hormonal research in sport (e.g. procedural issues, analytical methods, research design) were another discussion point. Finally, this review highlights the need for more experimental research on humans, in particular athletes, to specifically address the concept of dual steroid effects on the neuromuscular system.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.HUMOV.2015.11.011
Abstract: The specific movement demands of soccer that are linked to post-match recovery and readiness to train are unclear. Therefore, we examined the relationship between Global Positioning System (GPS) variables and the change (Δ from baseline) in Creatine Kinase (CK) concentrations and peak power output (PPO during the countermovement jump) at 24h and 48h post-match. Fifteen English Premier League reserve team players were examined over 1-4 matches. Measurements of CK and PPO were taken before (24h prior to match-play) and after (+24h and +48h) each game during which movement demands were quantified using 10Hz GPS data. High intensity distance covered (r=0.386, p=0.029 r=-0.349 p=0.050), high intensity distance covered⋅min(-1) (r=0.365, p=0.040 r=-0.364, p=0.040), high speed running distance (r=0.363, p=0.041 r=-0.360, p=0.043) and the number of sprints⋅min(-1) (r=0.410, p=0.020 r=-0.368, p=0.038) were significantly related to ΔCK and ΔPPO at +24h post-match, respectively. No relationships were observed between any match variables and ΔCK and ΔPPO after +48h of recovery. These findings highlight that high intensity match activities are related to ΔCK and ΔPPO in the 24h, but not 48h, following soccer match-play. Such information is likely of interest to those responsible for the design of soccer player's training schedules in the days following a match.
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.PHYSBEH.2015.04.017
Abstract: This study examined the salivary testosterone (T) and cortisol (C) responses of elite women hockey players across 4 activities (light and heavy training, club and International competitions). The players formed an oral contraceptive (OC) group (n=10) and a Non-OC (n=19) group for analysis. The Non-OC group had higher T levels (by 31-52%) across all activities, whilst the OC group showed signs of reduced T and C reactivity when data were pooled. As a squad, positive T and C changes occurred with heavy training (45%, 46%), club competitions (62%, 80%) and International competitions (40%, 27%), respectively. Our results confirm that OC use lowers T levels in women athletes whilst reducing the T and C responses to training and competition activities within the sporting environment. Differences in the physical and/or psychological demands of the sporting activity could be contributing factors to the observed hormone responses. These factors require consideration when applying theoretical models in sport, with broader implications for women around exercising behaviours and stress physiology.
Publisher: Elsevier BV
Date: 11-1999
DOI: 10.1016/S0031-9384(99)00107-9
Abstract: Early environmental effects including variation in maternal care, can modify hypothalamic-pituitary-adrenal (HPA) axis function. One of the more overt early effects, involving maternal care, is weaning restraint. In this study the effects of different patterns of weaning, in the rat (Rattus norvegicus), on both adult response to restraint stress and to dexamethasone administration were examined. Animals that as pups experienced a gradual lengthening time of separation from the mother, between 21 and 30 days of postnatal age (completely separated on 30 days), showed lower levels of systemic corticosterone and glutamate in the sensory cortex in response to restraint stress than seen in other groups. These animals also showed greater suppression of corticosterone by dexamethasone than did animals abruptly removed from the mother at 21 days of age. Animals left in the cage with the mother until either 30 or 40 days of age showed the greatest levels of corticosterone and glutamate in the sensory cortex in response to the stress and the least suppression by dexamethasone. These results suggest that changes in maternal contact at time of weaning can influence adult responsiveness to stress.
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.JSAMS.2021.08.017
Abstract: To compare two modes (general and cricket-specific) of morning priming exercise on afternoon physical and cognitive performance, and subjective readiness to perform in professional male cricketers. Randomised, crossover, counterbalanced. On three occasions, 16 professional men's cricketers completed afternoon tests of countermovement jump height, cricket-specific sprint performance (running between the wickets, two runs), cognitive function (Stroop test, time taken), and subjective readiness to perform. Control (CON passive rest), lower-body resistance exercise priming (LIFT trap bar deadlifts, 6 × 4 repetitions up to 85% of one repetition maximum), or cricket-specific running priming (RUN 6 × 35.36 m sprints including a 180° change of direction) interventions were implemented 5.5 h before testing. Afternoon sprint times were faster in RUN (-0.04 s, p = 0.013) and LIFT (-0.07 s, p 0.05), players reported favourable responses on the "aggression" subscale in LIFT relative to CON (+1 arbitrary unit, p = 0.022). Both general (lower-body resistance exercise) and cricket-specific (simulated running between wickets) morning priming are effective match-day strategies to improve afternoon markers of physical and cognitive performance in professional men's cricketers. Practitioners may thus be afforded flexibility in situations where resistance exercise is not feasible on the morning of a match.
Publisher: Informa UK Limited
Date: 26-04-2021
DOI: 10.1080/10253890.2021.1912004
Abstract: Reproducibility of social research is ambitious, and evidence supporting this argument is increasing in psychology and social science research. This may be attributed to, in part, the high volume of qualitative research methodology used in social research along with difficulties in the reliability of measurement techniques. Therefore, use of more and better objective measures to complement existing techniques in social research are necessitated. To highlight this point we explored the success of give-get nudge in adults. Nudge being a subtle intervention to influence choice, without restricting choice. We also wanted to explore whether testosterone and cortisol, as objective psychophysiological markers, could explain nudge outcome. Participants were asked what they would like to get for Christmas, or what they would like to give. They were then presented with two chocolates, one big and one small, and instructed to take as a "reward" for their participation with the knowledge there was one other participant to take chocolate after them. It was hypothesized that those asked to give something for Christmas would take the smaller reward and vice versa. Salivary testosterone and cortisol were measured prior to, and 10 min after completing the exercise. The nature of the nudge itself did not predict behavior, but the hormone measures did. We speculate that testosterone may focus an in idual on the nature of the question (nudge), while cortisol encourages self-focus. These results support the need to combine existing social research techniques with more objective markers.
Publisher: Human Kinetics
Date: 11-2016
Abstract: To examine the steroid hormone effect on the physical performance of young athletes during an Olympic weightlifting competition. 26 boys and 26 girls were monitored across 2 weightlifting competitions. Pre- and post-competition testosterone (T), cortisol (C) and dehydroepiandrosterone-sulfate (DHEA-s) were measured in blood, with pre-event free T (FT) and the free androgen index (FAI) calculated. Body mass (BM) and weightlifting performance were recorded. The boys had a larger BM, superior performance with more T, FT and a higher FAI than girls ( p .01). Although C (32%) and DHEA-s (8%) levels were elevated across competition, no sex differences in hormone reactivity were seen. In boys, DHEA-s correlated with performance ( r = .46), but not after controlling for BM ( r = .14). For girls, T correlated with performance (r = -0.51) after BM was controlled. The sex differences that emerge during puberty were observable, whereby the boys were larger and stronger with a more anabolic profile than girls. In idual DHEA-s (boys) and T (girls) levels were related to performance, but BM appeared to be acting as a mediating (boys) or suppressing (girls) variable. This adds new insight regarding the hormonal contribution to competitive performance in young athletes.
Publisher: Springer Science and Business Media LLC
Date: 12-12-2015
DOI: 10.1007/S40279-014-0297-0
Abstract: A number of intermittent team sports require that two consecutive periods of play (lasting for ~30-45 min) are separated by a 10-20 min half-time break. The half-time practices employed by team-sports players generally include returning to the changing rooms, temporarily relaxing from the cognitive and physical demands of the first half, rehydration and re-fuelling strategies, addressing injury or equipment concerns, and receiving tactical instruction and coach feedback. However, the typically passive nature of these actions has been associated with physiological changes that impair performance during the second half. Both physical and cognitive performances have been found to decline in the initial stages of subsequent exercise that follows half-time. An increased risk of injury has also been observed during this period. Therefore, half-time provides sports scientists and strength and conditioning coaches with an opportunity to optimise second-half performance. An overview of strategies thought to benefit team-sports athletes is presented specifically, the efficacy of heat maintenance strategies (including passive and active methods), post-activation potentiation, hormonal priming, and modified hydro-nutritional practices are discussed. A theoretical model of applying these strategies in a manner that compliments current practice is also offered.
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.JSAMS.2013.11.003
Abstract: Many International Rugby Board (IRB) sevens competitions require that two tournament stages are played over consecutive weekends, but the impact this has on player physical performance and recovery is lacking. We examined the influence of two consecutive tournaments on neuromuscular function (NMF) and muscle damage in rugby sevens players. Ten elite international rugby sevens players completed this observational study over 2 tournaments, separated by 5 days, during the IRB sevens series. On the morning of day 1 and 2, of both tournament 1 (T1) and 2 (T2), players performed countermovement jumps (CMJ jump height [JH]) and capillary blood s les (creatine kinase [CK]) were collected. After the last match of each day, further capillary s les were collected. Additional, CMJ were performed 12 and 60 h post-T1. Player JH decreased from day 1 to day 2 during T1 (mean ± SD -6.0 ± 5.4% P=0.016), was reduced at 12 (-26.1 ± 5.0% P<0.001) and 60 h post-T1 (-7.1 ± 4.8% P=0.003) and remained lower, at am day 1 of T2 (-8.0 ± 6.0% P=0.007), when compared with day 1 of T1. Player JH was lower on day 1 and 2 of T2, compared with T1 (P<0.05). CK concentrations were greater than baseline at all time points during each tournament (P<0.001) no between tournament differences in CK responses existed (P=0.302). A single sevens tournament reduces NMF such that players are not fully recovered by the start of the second competition stage, however CK returns to baseline in-between and shows the same pattern across two consecutive tournaments.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2021
DOI: 10.1519/JSC.0000000000002485
Abstract: Williams, N, Russell, M, Cook, CJ, and Kilduff, LP. Effect of ischemic preconditioning on maximal swimming performance. J Strength Cond Res 35(1): 221–226, 2021—The effect of ischemic preconditioning (IPC) on swimming performance was examined. Using a randomized, crossover design, national- and international-level swimmers ( n = 20 14 men, 6 women) participated in 3 trials (Con, IPC-2h, and IPC-24h). Lower-body IPC (4 × 5-minute bilateral blood flow restriction at 160–228 mm Hg and 5-minute reperfusion) was used 2 hours (IPC-2h) or 24 hours (IPC-24h) before a self-selected (100 m, n = 15 200 m, n = 5) swimming time trial (TT). The Con trial used a sham intervention (15 mm Hg) 2 hours before exercise. All trials required a 40-minute standardized precompetition swimming warm-up (followed by 20-minute rest replicating precompetition call room procedures) 1 hour before TT. Capillary blood (pH, blood gases, and lactate concentrations) was taken immediately before and after IPC, before TT and after TT. No effects on TT for 100 m ( P = 0.995 IPC-2h: 64.94 ± 8.33 seconds IPC-24h: 64.67 ± 8.50 seconds Con: 64.94 ± 8.24 seconds), 200 m ( P = 0.405 IPC-2h: 127.70 ± 10.66 seconds IPC-24h: 129.26 ± 12.99 seconds Con: 130.19 ± 10.27 seconds), or combined total time (IPC-2h: 84.27 ± 31.52 seconds IPC-24h: 79.87 ± 29.72 seconds Con: 80.55 ± 31.35 seconds) were observed after IPC. Base excess (IPC-2h: −13.37 ± 8.90 mmol·L −1 Con: −13.35 ± 7.07 mmol·L −1 IPC-24h: −16.53 ± 4.65 mmol·L −1 ), pH (0.22 ± 0.08 all conditions), bicarbonate (IPC-2h: −11.66 ± 3.52 mmol·L −1 Con: −11.62 ± 5.59 mmol·L −1 IPC-24h: −8.47 ± 9.02 mmol·L −1 ), total carbon dioxide (IPC-2h: −12.90 ± 3.92 mmol·L −1 Con: −11.55 ± 7.61 mmol·L −1 IPC-24h: 9.90 ± 8.40 mmol·L −1 ), percentage oxygen saturation (IPC-2h: −0.16 ± 1.86% Con: +0.20 ± 1.93% IPC-24h: +0.47 ± 2.10%), and blood lactate (IPC-2h: +12.87 ± 3.62 mmol·L −1 Con: +12.41 ± 4.02 mmol·L −1 IPC-24h: +13.27 ± 3.81 mmol·L −1 ) were influenced by swimming TT ( P 0.001), but not condition (all P 0.05). No effect of IPC was seen when applied 2 or 24 hours before swimming TT on any indices of performance or physiological measures recorded.
Publisher: Termedia Sp. z.o.o.
Date: 2018
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.CLINBIOCHEM.2012.11.019
Abstract: Salivary testosterone (T) and cortisol (C) concentrations were monitored across a sports competition. Data were compared using two enzyme-immunoassay (EIA) methods and two s le preparations to determine their influence on hormone concentrations. A group of male athletes (n=19) provided a saliva s le the morning before and one day after (24h post) an international rugby union match. Following an extraction procedure, the s les were analysed for T and C concentrations using a commercial kit (CM(E)) and an in-house method (IH(E)). Raw s les (no extraction procedure) were also tested using the commercial kit (CM(R)). There were no significant changes in T and C levels from pre to post competition with each EIA method and s le preparation, but significant differences in T (IH(E)>CM(E)>CM(R)) and C (CM(R)>IH(E) and CM(E)) concentrations were seen when both s les were pooled. Bland-Altman analyses confirmed the presence of fixed and proportional bias. Strong and significant correlations were demonstrated between the IH(E) and CM(E) measures of salivary T (r=0.93-0.97) and C (r=0.95-0.97). The T and C values from the raw and extracted s les were also strongly correlated (r=0.93-0.96). The measurement of salivary T and C concentrations across an international sports event was influenced by different EIA methods and s le preparations, but all measures were strongly correlated with some bias. Both T and C were unresponsive to the sports event, but within the group results large in idual variation was seen.
Publisher: Human Kinetics
Date: 09-2016
Abstract: To assess the effects of different modes of morning (AM) exercise on afternoon (PM) performance and salivary hormone responses in professional rugby union players. On 4 occasions (randomized, crossover design), 15 professional rugby players provided AM (~8 AM) and PM (~2 PM) saliva s les before PM assessments of countermovement-jump height, reaction time, and repeated-sprint ability. Control (passive rest), weights (bench press: 5 × 10 repetitions, 75% 1-repetition maximum, 90-s intraset recovery), cycling (6 × 6-s maximal sprint cycling, 7.5% body mass load, 54-s intraset recovery), and running (6 × 40-m maximal sprints, 20-s intraset recovery) interventions preceded (~5 h) PM testing. PM sprint performance improved ( P .05) after weights ( .15 ± 0.19 s, .04% ± 2.46%) and running ( .15 ± 0.17 s, .12% ± 2.22%) but not cycling ( P .05). PM jump height increased after cycling (0.012 ± 0.009 m, 2.31% ± 1.76%, P .001) and running (0.020 ± 0.009 m, 3.90% ± 1.79%, P .001) but not weights ( P = .936). Reaction time remained unchanged between trials ( P = .379). Relative to control (131 ± 21 pg/mL), PM testosterone was greater in weights (21 ± 23 pg/mL, 17% ± 18%, P = .002) and running (28 ± 26 pg/mL, 22% ± 20%, P = .001) but not cycling ( P = .072). Salivary cortisol was unaffected by AM exercise ( P = .540). All modes of AM exercise improved at least 1 marker of PM performance, but running appeared the most beneficial to professional rugby union players. A rationale therefore exists for preceding PM competition with AM exercise.
Publisher: Informa UK Limited
Date: 1998
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2013
Publisher: Georg Thieme Verlag KG
Date: 23-04-2010
Abstract: This study assessed an enzyme-immunoassay (EIA) kit for measuring the salivary testosterone (T) and cortisol (C) concentrations of weightlifters. Saliva s les (n=64) were collected from male and female weightlifters during normal training procedures and analysed for T and C using a commercial EIA kit and a criterion radioimmunoassay (RIA) method. Significant correlations were demonstrated between the EIA and RIA measurements of salivary T (r=0.72) and C (r=0.96) [corrected] concentrations (P females) and C (males=females) were consistent for both assay methods. In conclusion, a commercially available EIA kit provided valid measures of the salivary T and C concentrations of male and female weightlifters. Factors to consider when using an EIA kit include the hormone(s) of interest, the magnitude of the correlations, as well as the descriptive information gained (e. g. absolute, relative) and its uses within sport.
Publisher: Elsevier BV
Date: 2012
DOI: 10.1016/J.YHBEH.2011.09.006
Abstract: Previous studies have shown that visual images can produce rapid changes in testosterone concentrations. We explored the acute effects of video clips on salivary testosterone and cortisol concentrations and subsequent voluntary squat performance in highly trained male athletes (n=12). Saliva s les were collected on 6 occasions immediately before and 15 min after watching a brief video clip (approximately 4 min in duration) on a computer screen. The watching of a sad, erotic, aggressive, training motivational, humorous or a neutral control clip was randomised. Subjects then performed a squat workout aimed at producing a 3 repetition maximum (3RM) lift. Significant (P<0.001) relative (%) increases in testosterone concentrations were noted with watching the erotic, humorous, aggressive and training videos (versus control and sad), with testosterone decreasing significantly (versus control) after the sad clip. The aggressive video also produced an elevated cortisol response (% change) and more so than the control and humorous videos (P<0.001). A significant (P<0.003) improvement in 3RM performance was noted after the erotic, aggressive and training clips (versus control). A strong within-in idual correlation (mean r=0.85) was also noted between the relative changes in testosterone and the 3RM squats across all video sessions (P<0.001). In conclusion, different video clips were associated with different changes in salivary free hormone concentrations and the relative changes in testosterone closely mapped 3RM squat performance in a group of highly trained males. Thus, speculatively, using short video presentations in the pre-workout environment offers an opportunity for understanding the outcomes of hormonal change, athlete behaviour and subsequent voluntary performance.
Publisher: Canadian Science Publishing
Date: 12-2012
DOI: 10.1139/H2012-101
Abstract: Repeated cycles of vascular occlusion followed by reperfusion initiate a protective mechanism that acts to mitigate future cell injury. Such ischemic episodes are known to improve vasodilation, oxygen utilization, muscle function, and have been demonstrated to enhance exercise performance. Thus, the use of occlusion cuffs represents a novel intervention that may improve subsequent exercise performance. Fourteen participants performed an exercise protocol that involved lower-body strength and power tests followed by repeated sprints. Occlusion cuffs were then applied unilaterally (2 × 3-min per leg) with a pressure of either 220 (intervention) or 15 mm Hg (control). Participants immediately repeated the exercise protocol, and then again 24 h later. The intervention elicited delayed beneficial effects (24 h post-intervention) in the countermovement jump test with concentric (effect size (ES) = 0.36) and eccentric (ES = 0.26) velocity recovering more rapidly compared with the control. There were also small beneficial effects on 10- and 40-m sprint times. In the squat jump test there were delayed beneficial effects of occlusion on eccentric power (ES = 1.38), acceleration (ES = 1.24), and an immediate positive effect on jump height (ES = 0.61). Thus, specific beneficial effects on recovery of power production and sprint performance were observed both immediately and 24 h after intermittent unilateral occlusion was applied to each leg.
Publisher: Informa UK Limited
Date: 09-08-2015
DOI: 10.1080/17461391.2015.1053419
Abstract: No published research has assessed sleep patterns of elite rugby union players following match-play. The present study examined sleep patterns of professional rugby union players, prior and post-match-play, to assess the influence of competition. Twenty-eight male rugby union players (24.4 ± 2.9 years, 103.9 ± 12.2 kg) competed in one of four competitive home matches. Player's sleep behaviours were monitored continuously using an Actiwatch® from two days before the match, until three days post-match. Repeated measures of analysis of variance (ANOVA) showed significant differences across the time points measured for time to bed (F = 26.425, η(2) = 0.495, p < .001), get up time (F = 21.175, η(2) = 0.440, p < .001), time spent in bed (F = 10.669, η(2) = 0.283, p < .001), time asleep (F = 8.752, η(2) = 0.245, p < .001) and percentage of time moving (F = 4.602, η(2) = 0.146 p < .05). Most notable, post hocs revealed a significant increase for time in bed the night before the match (p < .01 95% CI = 0 : 10-1 : 28 h 9.7 ± 13.5%) compared with the reference night sleep. Furthermore, time asleep significantly decreased post-match (p < .05 95% CI = -0:03 to -1:59 h -19.5 ± 19.8%) compared to two nights pre-match. Across all time points, sleep latency and efficiency for most players were considered abnormal compared to that expected in normal populations. The results demonstrate that sleep that is deprived post-match may have detrimental effects on the recovery process.
Publisher: Springer Science and Business Media LLC
Date: 2006
DOI: 10.2165/00007256-200636030-00004
Abstract: The endocrine system plays an important role in strength and power development by mediating the remodelling of muscle protein. Resistance training scheme design regulates muscle protein turnover by modifying the anabolic (testosterone, growth hormone) and catabolic (cortisol) responses to a workout. Although resistance exercise increases the concentrations of insulin-like growth factor 1 in blood following exercise, the effect of scheme design is less clear, most likely due to the different release mechanisms of this growth factor (liver vs muscle). Insulin is non-responsive to the exercise stimulus, but in the presence of appropriate nutritional intake, elevated blood insulin levels combined with resistance exercise promotes protein anabolism. Factors such as sex, age, training status and nutrition also impact upon the acute hormonal environment and, hence, the adaptive response to resistance training. However, gaps within research, as well as inconsistent findings, limit our understanding of the endocrine contribution to adaptation. Research interpretation is also difficult due to problems with experimental design (e.g. s ling errors) and various other issues (e.g. hormone rhythms, biological fluid examined). In addition to the hormonal responses to resistance exercise, the contribution of other acute training factors, particularly those relating to the mechanical stimulus (e.g. forces, work, time under tension) must also be appreciated. Enhancing our understanding in these areas would also improve the prescription of resistance training for stimulating strength and power adaptation.
Publisher: Springer Science and Business Media LLC
Date: 03-11-2014
Publisher: Public Library of Science (PLoS)
Date: 05-11-2014
Publisher: Elsevier BV
Date: 04-1997
DOI: 10.1016/S0165-0270(96)02175-9
Abstract: Measurements of neurotransmitters in conscious animals have been restrictive in real-time. The use of specific enzymes within an erometric probe, based upon a microdialysis membrane, may overcome some of these problems. I report the use of such a probe, with different perfusions of enzymes, to allow real-time measurement of glutamate, catecholamines and indoleamines, in conscious animals. At an adjacent site microdialysis s le collections were made concurrently and neurotransmitters measured in the dialysate. Both probes were positioned within the somatosensory cortex. Values obtained by erometric probes were similar to those in dialysate s les for glutamate, catecholamines and indoleamines during basal and stimuli related collections. Amperometric measurements showed higher peak concentrations and better time resolution than dialysate s ling. This reflects s ling differences. Application of external stimuli increased extracellular concentrations of glutamate, catecholamines and indoleamines, in both forms of s ling. Dopamine measurements did not correlate well between the two forms of s ling. This may reflect the non-specificity of the enzyme (dopamine-beta-hydroxylase) used in the erometric probe. This combination, of microdialysis and erometry, offers a useful tool for real-time neurotransmitter studies in vivo.
Publisher: Human Kinetics
Date: 07-2019
Abstract: Purpose : To examine changes in, and relationships between, sleep quality and quantity, salivary testosterone, salivary cortisol, testosterone-to-cortisol ratio (T:C), and self-reported muscle soreness during a residential-based training c in elite rugby players. Methods : Nineteen male rugby players age 26.4 (3.9) years, height 186.0 (9.4) cm, and weight 104.1 (13.4) kg (mean [SD]) participated in this study. Wrist actigraphy devices were worn for 8 nights around a 4-d training c (2 nights prior, during, and 2 nights after). Sleep-onset latency, sleep duration, sleep efficiency, and waking time were measured. Participants provided saliva s les during c on waking and again 45 min later, which were then assayed for testosterone and cortisol levels. They also rated their general muscle soreness daily. Results : Little variation was observed for sleep quality and quantity or testosterone. However, significant differences were observed between and within days for cortisol, T:C, and muscle soreness ( P .001). Few relationships were observed for sleep and hormones the strongest, an inverse relationship for sleep efficiency and T:C ( r = −.372, P .01). Conclusions : There may be no clear and useful relationship between sleep and hormone concentration in a short-term training c context, and measures of sleep and testosterone and cortisol should be interpreted with caution because of in idual variation. Alterations in hormone concentration, particularly cortisol, may be affected by other factors including anticipation of the day ahead. This study adds to our knowledge that changes in hormone concentration are in idual and context specific.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2014
Publisher: Human Kinetics
Date: 2014
Abstract: To examine the effects of moderate-load exercise with and without blood-flow restriction (BFR) on strength, power, and repeated-sprint ability, along with acute and chronic salivary hormonal parameters. Twenty male semiprofessional rugby union athletes were randomized to a lower-body BFR intervention (an occlusion cuff inflated to 180 mmHg worn intermittently on the proximal thighs) or a control intervention that trained without occlusion in a crossover design. Experimental sessions were performed 3 times a week for 3 wk with 5 sets of 5 repetitions of bench press, leg squat, and pull-ups performed at 70% of 1-repetition maximum. Greater improvements were observed (occlusion training vs control) in bench press (5.4 ± 2.6 vs 3.3 ± 1.4 kg), squat (7.8 ± 2.1 vs 4.3 ± 1.4 kg), maximum sprint time (−0.03 ± 0.03 vs –0.01 ± 0.02 s), and leg power (168 ± 105 vs 68 ± 50 W). Greater exercise-induced salivary testosterone (ES 0.84–0.61) and cortisol responses (ES 0.65–0.20) were observed after the occlusion intervention sessions compared with the nonoccluded controls however, the acute cortisol increases were attenuated across the training block. Occlusion training can potentially improve the rate of strength-training gains and fatigue resistance in trained athletes, possibly allowing greater gains from lower loading that could be of benefit during high training loads, in competitive seasons, or in a rehabilitative setting. The clear improvement in bench-press strength resulting from lower-body occlusion suggests a systemic effect of BFR training.
Publisher: Springer Science and Business Media LLC
Date: 11-1988
DOI: 10.1203/00006450-198811000-00012
Abstract: Clinical studies suggest that growth-retarded prematurely delivered infants are neurologically precocious. We investigated this paradoxical observation in the fetal lamb. Somatosensory and brainstem auditory-evoked potentials were studied in chronically instrumented fetal lambs in late gestation with varying degrees of growth retardation induced by preconception uterine carunclectomy. The components of the brainstem auditory-evoked response appeared earlier (p less than 0.05) in fetuses at least 2 SD less than the mean weight for gestational age (n = 5) compared to normal controls (n = 8) or carunclectomized fetuses of normal size (n = 7). Several waveforms of both the somatosensory (N20, P/N 30, and P200) and the brainstem auditory-evoked response (I, III, IV, and V) demonstrated shorter (p less than 0.05) latencies in growth-retarded fetuses relative to normal-sized fetuses. The ability to follow increasing stimulus rates for both stimuli also demonstrated precocial maturation (p less than 0.05) in growth-retarded as compared to normal-sized fetuses. Growth retardation is thus associated with precocial neurologic maturation in utero.
Publisher: Elsevier BV
Date: 04-2006
DOI: 10.1016/J.PHYSBEH.2006.01.011
Abstract: Marked increases in anxiety-like responses to stress occur during pregnancy. Considerable evidence indicates that the basolateral region of the amygdala (BLA) plays an important role in mediating these types of responses. Given the crucial inhibitory influence of GABA on excitatory glutamatergic activity in the BLA, we hypothesized that decreased GABAergic activity in this region may underlie the increased anxiety associated with pregnancy. In vivo microdialysis was used to s le extracellular GABA before and after 30 min of restraint stress. While there was no detectable effect of restraint on extracellular GABA concentrations, basal GABA levels were significantly decreased in pregnant rats compared with either virgin females or males. We suggest that the alterations in anxiety-like behavior that occur during pregnancy may be associated with decreased basal GABA in the BLA.
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.NBD.2014.05.004
Abstract: Huntington's disease (HD) is a neurodegenerative disorder caused by a tandem repeat mutation in the huntingtin gene. Lifestyle factors, such as lack of activity may contribute to the variability in the age of disease onset. Therefore, better understanding of environmental modifiers may uncover potential therapeutic approaches to delay disease onset and progression. Recent data suggest that HD patients and transgenic mouse models show a dysregulated stress response. In this present study, we elevated stress hormone levels through oral corticosterone (CORT) treatment and assessed its impact on the development of motor impairment and cognitive deficits using the R6/1 transgenic mouse model of HD. We found that CORT consumption did not alter rotarod performance of R6/1 HD or wild-type (WT) littermates. However, the onset of hippoc al-dependent Y-maze deficits was accelerated in male R6/1 mice by 5days of CORT treatment, whereas short term memory of WT and female R6/1 mice was unaffected. We then further investigated the male HD susceptibility to CORT by measuring TrkB activation, BDNF and glucocorticoid receptor expression as well as the level of cell proliferation in the hippoc us. CORT treatment increased the levels of phosphorylated TrkB in male R6/1 mice only. There were no effects of CORT on hippoc al BDNF protein or mRNA levels nor on expression of the glucocorticoid receptors in any group. Hippoc al cell proliferation was decreased in male R6/1 mice and this was further reduced in CORT-drinking male R6/1 mice. Female mice (WT and R6/1) appeared to be protected from the impacts of CORT treatment in all our hippoc al measures. Overall, our data demonstrate that treatment with corticosterone is able to modulate the onset of HD symptomatology. We present the first evidence of a male-specific vulnerability to stress impacting on the development of short-term memory deficits in HD. More generally, we found that female mice were protected from the detrimental effects of CORT treatment on a variety of hippoc us-based measures. Hippoc al plasticity and memory in HD may be more susceptible to the impacts of stress in a sex-dependent manner. We propose clinical investigations of stress as a key environmental modifier of HD symptom onset.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2014
Publisher: Informa UK Limited
Date: 09-1993
DOI: 10.1080/00480169.1993.35750
Abstract: Eighteen of 23 red deer (Cervus elaphus) at a deer slaughtering premises were successfully stunned with an apparatus modified from that normally used to stun sheep. The five unsuccessful electrical stuns were associated with poor head restraint and poor head contact by the electrodes. The median stunning current was 0.9 A, and in the majority of cases the duration of stunning was less than 1 second. The signs of the electrically induced epileptiform seizures in the deer were dissimilar to those seen in sheep, cattle and pigs, in that the initial tonic phase was less marked, and of shorter duration. A similar shorter and less obvious tonic phase was noted in four deer shot with a captive bolt pistol. Two animals which were electrically stunned, and bled within 10 seconds, showed no signs of recovery while bleeding. The electroencephalograms of four deer stunned with currents of 1.3 A for a duration of either 0.5 or 1.0 seconds were recorded under more controlled conditions. All four animals developed electroencephalograms typical of an epileptiform seizure. The animals exhibited behavioural reactions similar to the other 18 animals in the trial at the deer slaughtering premises and were rendered unconscious for between 54 and 122 seconds. The electroencephalogram activity litude was greater than that recorded immediately before stunning and took between 6 and 9 seconds to build up to maximum value. It is concluded that, providing the heads of deer are adequately restrained, head-only electrical stunning can be incorporated into a humane method of slaughter for deer.
Publisher: Elsevier BV
Date: 08-2009
DOI: 10.1016/J.RVSC.2009.01.003
Abstract: The aim of this study was to assess whether environmental enrichment and environmental conditions can influence the expression of sickness behaviour. The behaviour in response to injection of lipopolysaccharide or saline was examined in a total of 96 62-weeks old hatchmate hens kept in a free range or cage environment. There were eight experimental treatments, each with 12 birds. Half the birds were sourced from a commercial cage layer unit (C/-) and half from a commercial free range unit (FR/-). After intraperitoneal injection with either lipopolysaccharide or saline (as a control), the hens were placed in either a cage (-/C) or free range (-/FR) environment. Lipopolysaccharide caused greater suppression of activity in free range (FR/FR) than in caged hens, including less walking (53% reduction), roosting (-86%) and preening (-60%) (p<0.05). Those responses were not observed in caged birds released into free range, nor in free range birds introduced to cages, suggesting that both the presence of and the familiarity with an environment affected sickness behaviour patterns. Increased sleeping was the most consistent response (+147% p<0.001), and it was least influenced by environment. It was concluded that free range layer hens can express a greater range of sickness behaviours than caged hens, and this may make it more difficult to recognise disease expression in the caged environment.
Publisher: Springer Science and Business Media LLC
Date: 11-2017
Publisher: Routledge
Date: 20-11-2014
Publisher: Informa UK Limited
Date: 13-09-2013
DOI: 10.3109/00365513.2013.835862
Abstract: Measurement of steroid hormones in saliva is increasingly common in elite sport settings. However, this environment may enforce handling and storage practices that introduce error in measurement of hormone concentrations. We assessed the influence of storage temperature and duration on reproducibility of salivary steroid levels. Nine healthy adults provided morning and afternoon saliva s les on two separate occasions. Each s le was ided into identical saliva aliquots which were stored long-term (i.e. 28 and 84 days) at - 80°C or - 20°C (testing day 1), and short-term (i.e. 1, 3, 7 and 14 days) at 4°C or 20°C (testing day 2). S les were analyzed for cortisol, testosterone and estradiol using ELISA. In non-freezer conditions, there was a decrease from baseline to 7 days in testosterone (- 26 ± 15%) and estradiol (- 58 ± 17%) but not cortisol concentrations (p < 0.001). This decrease was larger in s les stored at room temperature than in the refrigerator (p ≤ 0.01). There were small but significant changes in measured concentrations of all hormones after 28 and/or 84 days of storage in freezer conditions (p ≤ 0.01), but these were generally within 12% of baseline concentrations, and may be partly explained by inter-assay variability. Whole saliva s les to be analyzed for cortisol, testosterone and estradiol should be frozen at - 20°C or below within 24 h of collection, and analyzed within 28 days. Storage of s les for measurement of testosterone and estradiol at temperatures above - 20°C can introduce large error variance to measured concentrations.
Publisher: Public Library of Science (PLoS)
Date: 07-04-2016
Publisher: Hindawi Limited
Date: 2013
DOI: 10.1155/2013/952350
Abstract: Aim . The aim of the present study was to investigate the relationship between maximal aerobic capacity () and repeated sprint ability (RSA) in a group of professional soccer players. Methods . Forty-one professional soccer players (age yrs, height cm, weight kg) were required to perform tests to assess RSA and on two separate days with at least 48 hr rest between testing sessions. Each player performed a treadmill test to determine their and a test for RSA involving the players completing m sprints (turn after 20 m) with 20 s active recovery between each sprint. Results . There was a significant negative correlation between body mass normalised and mean sprint time () ( ) and total sprint time () (, ). Conclusion . Results of the current study indicate that is one important factor aiding soccer players in the recovery from repeated sprint type activities.
Publisher: Informa UK Limited
Date: 04-1998
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2011
Publisher: Informa UK Limited
Date: 18-01-2021
Publisher: Informa UK Limited
Date: 02-03-2020
Publisher: Elsevier BV
Date: 10-2001
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2009
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.JSAMS.2012.06.002
Abstract: Swimmers must enter a marshalling call-room 20min prior to racing, which results in some swimmers completing their warm-up 45min pre-race. Since a recovery period longer than 15-20min may prove problematic, this study examined 200m freestyle performance after a 20 and 45min post-warm-up recovery period. Eight international swimmers completed this randomised and counter-balanced study. After a standardised warm-up, swimmers rested for either 20 (20min) or 45min (45min) prior to completing a 200m freestyle time-trial (TT). Core temperature (T(core)), blood lactate (BL), heart rate and rate of perceived exertion (RPE) were recorded at baseline, post-warm-up, pre-TT, immediately post-TT and at 3min post-TT. T(core) was similar after the warm-up under both conditions, however, at pre-TT T(core) was greater under 20min (mean±SD 20min 37.8±0.2 vs. 45min 37.5±0.2°C P=0.002). BL was similar between conditions at all-time points before the TT (P>0.05). Swimmers demonstrated a 1.5±1.1% improvement in performance under 20min (20min 125.74±3.64 vs. 45min 127.60±3.55s P=0.01). T(core) was similar between conditions at immediately post-TT and 3min post-TT (P>0.05), however, BL was higher at these time points under 20min (P 0.05). 200m freestyle performance is faster 20min post-warm-up when compared to 45min probably due to better T(core) maintenance. This has implications for swim race preparation as warm-up procedures should be completed close to entering the pre-race call room, in order to maintain elevated core temperature.
Publisher: SAGE Publications
Date: 28-10-2021
Abstract: High-performance sport coaches are leaders in their field therefore, they sometimes operate under ‘regular’ workplace leadership role requirements. However, they are also subject to highly uncertain and pressured environments. Thus, most coaching/leadership positions in high-performance sport may be both ‘normal’ and ‘unique’ in leadership role requirement. Consequently, understanding what high-performance sport leaders ‘look like’, behaviorally, would be valuable. This study aimed to 1) describe personality traits of coaches in high-performance sport, and 2) describe differences between high-performance sport coaches and other leaders. Hogan’s personality profile data was collected from fulltime coaches working in high-performance sport. Experienced and developing high-performance sport coaches were compared, and high-performance sport coaches were compared to other sector leaders. No differences exist between coaching groups for any personality traits. However, while high-performance sport coaches shared similar ‘light’, or ‘socially desirable’, traits to leaders in ‘regular’ workplaces they differed for some ‘dark’/maladaptive traits. That is, as is the case for leaders in sectors including business, finance and healthcare high-performance coaches may be experienced as being balanced, stable, calm under pressure, approachable, friendly, accessible, planful, responsible, and mindful of details. However, unlike leaders in ‘regular’ workplace environments, high-performance coaches may also be experienced as moody, hard to please, creative but unusual, risk-taking, and limit-testing which is more similar to scientists and artists. In conclusion, coach personality traits were both similar and unique to leaders from ‘regular’ workplaces. Thus, leadership is context specific both within sectors and between sectors.
Publisher: Human Kinetics
Date: 2019
Abstract: Objective : To examine the effect of a physical treatment (speed, power, and strength [SPS] training) and psychosocial treatment (group motivational presentation) on salivary testosterone (sal-T), salivary cortisol (sal-C), and sal-T-to-sal-C ratio (T:C) in professional rugby. Methods : Fourteen male rugby players (age = 25.9 [2.5] y, height = 186.1 [6.7] cm, and body mass = 104.1 [12.7] kg) participated in this study. Testing occurred across 2 d on 2 separate occasions (week 1 and week 2). On day 1 of both weeks, participants completed an SPS training session. On day 2 of both weeks, participants undertook a field-based rugby training session. In week 2, participants underwent an additional treatment in the form of a motivational presentation given by a respected former player before the rugby session. Saliva was collected before and after SPS training and before and after the rugby session and was assayed for testosterone and cortisol. Results : No differences were found between weeks for sal-T at any time point, but sal-C was higher in week 2 before and after SPS and before rugby on day 2 ( P .05). In both weeks, T:C increased following SPS ( P .02, ES 0.91 [0.13, 1.69]). T:C increased when the motivational presentation accompanied rugby training ( P = .07, ES = 1.06 [0.27, 1.85]). Sal-C, not sal-T, drove changes in T:C ( P .001). Conclusions : Physical or psychosocial treatments may affect sal-T, sal-C, and T:C, and in idual variation in responses to treatments may exist.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2019
DOI: 10.1519/JSC.0000000000001897
Abstract: Jonathan, N, Russell, M, Shearer, D, Cook, CJ, and Kilduff, LP. Predictors of linear and multidirectional acceleration in elite soccer players. J Strength Cond Res 33(2): 514–522, 2019—Linear and multidirectional acceleration underpins success in professional soccer match play. However, the physical qualities that determine these performance indicators are poorly understood in elite players. English Premier League players ( n = 26) performed isometric midthigh pulls (IMTPs), bilateral and unilateral drop jumps (from 40 and 20 cm, respectively), bilateral and unilateral countermovement jumps (CMJs), and assessments of linear (5, 10, and 20 m) and multidirectional (left and right preplanned and reactive) acceleration. Regression analyses highlighted that 21% of variance in 5-m sprint time (1.02 ± 0.07 seconds) was explained by relative peak power output (PPO) in bilateral CMJ (54.5 ± 5.3 W·kg −1 ). A 5.4 W·kg −1 increase in CMJ predicted a 0.03-second decrease in 5-m sprint time ( P = 0.02). For 10-m sprint time (1.72 ± 0.09 seconds), 44% of variance was explained by isometric relative peak force ([PF] 30.4 ± 4.9 N·kg −1 ) and bilateral relative CMJ PPO (54.5 ± 5.3 W·kg −1 ). A 5.4 W·kg −1 increase in CMJ predicted reduced 10-m sprint times by 0.04 seconds ( P = 0.01). For 20-m sprint time (2.94 ± 0.11 seconds), 55% of the total variance was explained by isometric relative PF (30.4 ± 4.9 N·kg −1 ) and relative CMJ PPO (54.5 ± 5.3 W·kg −1 ). Increases of 5.4 W·kg −1 in bilateral CMJ predicted an improvement of 20-m sprint time by 0.06 seconds ( P = 0.002). Contributions were insignificant ( P 0.05) for preplanned and reactive multidirectional acceleration. Relativized indices, especially those related to force production during CMJ and IMTP tests, likely underpin linear but not multidirectional acceleration performance in professional soccer players. When linear acceleration is a training focus, practitioners should seek to monitor CMJ and IMTP test performance.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2011
Publisher: Informa UK Limited
Date: 25-08-2016
DOI: 10.1080/17461391.2016.1220628
Abstract: This study examined the moderating effect of cortisol (C) on the relationship between testosterone (T) and hand-grip strength (HGS) in healthy young men. Sixty-five males were monitored for salivary T, C and HGS before and 15 min after a short bout (5 × 6-s trials) of sprint cycling exercise. Sprint exercise promoted (p < .05) positive changes in T (6.1 ± 24.9%) and HGS (3.4 ± 7.5%), but a negative C response (-14.4 ± 33.1%). The T and C measures did not independently predict HGS, but a significant T × C interaction was found in relation to these outcomes. Further testing revealed that pre-test T and HGS were negatively associated (p < .05), but only in men with high C levels. The exercise changes in T and HGS were also negatively related in men with low C levels (p < .05), but no relationship was seen in men with high C levels. In summary, complex relationships between T and HGS emerged when considering C as a moderating variable. The pre-test combination of high C and low T levels favoured absolute HGS, whereas low pre-test C levels and a smaller T change were linked to larger HGS changes. These associations suggest that, in the current format, T is not necessarily anabolic to muscle strength in healthy young men. Such complexities could also explain some of the inconsistent T relationships with physical performance in lesser trained male populations.
Publisher: Elsevier BV
Date: 08-1998
DOI: 10.1016/S0165-0270(98)00046-6
Abstract: A method is described for the measurement of gamma-amino-4-butyric acid (GABA) within a microdialysis probe using an antibody-linked assay. A monoclonal antibody for GABA provides the specificity of measurement and these antibodies are affixed on a working platinum electrode within the probe. Determination of bound GABA is performed via an indirect assessment of competitive ligand also bound, and conjugated to horseradish peroxidase which is activated and measured as current change. Using this probe directly for extracellular measurements in the somatosensory cortex of sheep compared favorably to the use of this probe on dialysate emerging from a classical microdialysis probe suggesting that it could be used directly in vivo. The probe has a fast response time (> 90% of maximum response within 30 s of start of analysis) and high sensitivity ( 48 h) and is regenerable. The probe design offers on-line measurement, with rapid time resolution of substances not amenable to enzyme-based erometric measurement.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2020
DOI: 10.1519/JSC.0000000000002185
Abstract: Russell, M, Reynolds, NA, Crewther, BT, Cook, CJ, and Kilduff, L. Physiological and performance effects of caffeine gum consumed during a simulated half-time by professional academy rugby union players. J Strength Cond Res 34(1): 145–151, 2020—Despite the prevalence of caffeine (CAF) as an ergogenic aid, few studies have examined the use of caffeinated gums, especially during half-time in team sports. The physiological (blood lactate and salivary hormone concentrations) and performance (repeated sprints and cognitive function) effects of consuming CAF gum during a simulated half-time were examined. Professional academy rugby union players ( n = 14) completed this double-blind, randomized, counterbalanced study. After pre-exercise measurements, players chewed a placebo (PLC) gum for 5 minutes before a standardized warm-up and completing repeated sprint testing (RSSA1). Thereafter, during a 15-minute simulated half-time period, players chewed either CAF (400 mg 4.1 ± 0.5 mg·kg −1 ) or PLC gum for 5 minutes before completing a second repeated sprint test (RSSA2). Blood lactate, salivary testosterone and cortisol concentrations, and indices of cognitive function (i.e., reaction time and Stroop test) were measured at baseline, pre-RSSA1, post-RSSA1, pre-RSSA2, and post-RSSA2. Sprint performance was not affected by CAF ( p = 0.995) despite slower sprint times after the first sprint of both RSSA tests (all p 0.002). After half-time, salivary testosterone increased by 70% (+97 ± 58 pg·ml −1 ) in CAF vs. PLC ( p 0.001), whereas salivary cortisol remained unchanged ( p = 0.307). Cognitive performance was unaffected by time and trial (all p 0.05). Although performance effects were absent, chewing CAF gum increased the salivary testosterone concentrations of professional rugby union players over a simulated half-time. Practitioners may, therefore, choose to recommend CAF gum between successive exercise bouts because of the increases in salivary testosterone observed a variable associated with increased motivation and high-intensity exercise performance.
Publisher: Informa UK Limited
Date: 04-2004
DOI: 10.1080/00480169.2004.36408
Abstract: To compare the effects of four stocking densities (5, 10, 15 or 20 birds per m2) on the performance, carcass characteristics and selected welfare indicators of broiler chickens. A total of 756 day-old male broiler chicks were assigned as six replicates of 13, 25, 38 and 50 birds per pen, to stocking densities of 2,000, 1,000, 667 and 500 cm2 floor space per bird, respectively. The birds were housed in floor pens in an environmentally controlled room. Normal commercial diets were fed ad libitum and fresh water was freely available throughout the 5-week study period. Liveweights of birds and feed intake were recorded at weekly intervals. Data on carcass parameters and welfare indicators (moisture, gait scores, feather scores, breast and hip lesions, and foot pad and hock burns) were obtained on Day 35. Adrenal glands were removed at slaughter, weighed and examined histologically to determine the total proportion of cortical and medullary tissues. During the study, the birds at the lowest density grew faster (p<0.001-0.01) and consumed more (p<0.001- 0.01) feed than those at the other three stocking densities. The liveweight gains and feed intake of birds reared at densities of 10, 15 and 20 birds per m2 were similar (p=0.11-0.83 and p=0.17-0.57, respectively). Stocking density had no influence on the feed/weight gain, mortality or carcass characteristics. No breast or hip lesions were observed in carcasses from any of the groups. The weight and structure of the adrenal glands were similar across all groups although the staining of medullary tissue of birds was most intense in the highest stocking density group. As stocking density increased, so did moisture and gait score, hock and foot pad burn scores, and the feather score was adversely affected. The data showed that the relationship between stocking density and productivity traits was not linear in nature, in accordance with other studies. Under the conditions of the current study, the performance, mortality and carcass characteristics of broilers grown at densities of 10, 15 and 20 birds per m2 were similar. There were some welfare implications at high population densities as indicated by adverse effects on litter quality, gait scores and the incidence of hock and foot pad burns.
Publisher: Elsevier BV
Date: 02-2002
DOI: 10.1016/S0309-1740(01)00115-2
Abstract: Immediately after electrical stimulation, the paired m. longissimus thoracis et lumborum (LT) of 40 sheep were boned out and wrapped tightly with a polyethylene cling film. One of the paired LT's was chilled in 15°C air to reach a rigor mortis (rigor) temperature of 18°C and the other side was placed in a water bath at 35°C and achieved rigor at this temperature. Wrapping reduced rigor shortening and mimicked meat left on the carcass. After rigor, the meat was aged at 15°C for 0, 8, 26 and 72 h and then frozen. The frozen meat was cooked to 75°C in an 85°C water bath and shear force values obtained from a 1×1 cm cross-section. The shear force values of meat for 18 and 35°C rigor were similar at zero ageing, but as ageing progressed, the 18 rigor meat aged faster and became more tender than meat that went into rigor at 35°C (P<0.001). The mean sarcomere length values of meat s les for 18 and 35°C rigor at each ageing time were significantly different (P<0.001), the s les at 35°C being shorter. When the short sarcomere length values and corresponding shear force values were removed for further data analysis, the shear force values for the 35°C rigor were still significantly greater. Thus the toughness of 35°C meat was not a consequence of muscle shortening and appears to be due to both a faster rate of tenderisation and the meat tenderising to a greater extent at the lower temperature. The cook loss at 35°C rigor (30.5%) was greater than that at 18°C rigor (28.4%) (P<0.01) and the colour Hunter L values were higher at 35°C (P<0.01) compared with 18°C, but there were no significant differences in a or b values.
Publisher: Informa UK Limited
Date: 04-1998
DOI: 10.1080/00480169.1998.36059
Abstract: As sex related differences in opioid-induced elevations of nociceptive thresholds have been observed in sheep, a study was undertaken to determine if puberty, oestrus, pregnancy or administration of the hormones oestrogen and testosterone had any effect on these differences. Withdrawal latency to a nociceptive thermal source was measured in Romney cross sheep consisting of lambs (n = 6) prior to and after their first oestrus, ram lambs (n = 6) prior to and after puberty, non-oestrous ewes (n = 6), oestrous ewes (n = 6), pregnant and subsequently suckling ewes (n = 12), wethers (n = 6) and rams (n = 6). The effects of a kappa opioid agonist (GR 89696), oestradiol benzoate, testosterone and saline on this withdrawal latency were tested in all groups. GR 89696 increased withdrawal latency in all animals, compared to saline, but this was most marked in ewes, particularly those in oestrus or in late pregnancy. Testosterone and oestradiol had no effect on their own, or in combination, on the withdrawal latency seen with saline alone. Oestradiol increased the effects of GR 89696 on lambs pre-pubertal ram lambs, ewes and wethers but not on post-pubertal ram lambs nor rams. Co-administration of testosterone antagonised this oestradiol effect. The efficacy of kappa opioids appears to be affected by animal sex, an effect that can be contributed to by both oestradiol and testosterone.
Publisher: Elsevier BV
Date: 06-2002
DOI: 10.1016/S0039-128X(02)00010-7
Abstract: A series of progesterone-4-ovalbumin (OVA) conjugates with different length linkers (4-, 11-, and 18-atoms long) were synthesized by successive aminocaproic acid homologation of 3-(pregn-4-ene-3,20-dione-4-yl)thiopropanoic acid (1) before conjugation to ovalbumin. The performance studies of these progesterone-4-ovalbumin conjugates showed that the effects of the length of linker on the antibody binding are dependent upon different immunoassay formats. In a rapid flow biosensor surface, on a BIAcore Surface Plasmon Resonance (SPR) instrument, antibody-binding capacities and response rate were dramatically increased for progesterone-4-ovalbumin conjugates when the length of the linker was incremented from 4 atoms to 11 or 18 atoms. Thus, highly sensitive SPR-based immunoassays for progesterone over a range of 0.1-50 ng ml(-1) were developed using biosensor surfaces immobilized with progesterone-ovalbumin conjugates having extended linkers. The SPR-based assays were fully competitive with conventional enzyme-linked immunosorbant assay (ELISA) but much more rapid and simple. However, there were little changes in antibody-binding performance using a conventional ELISA for the same conjugates. The progesterone-4-ovalbumin conjugate (1-OVA) had better antibody binding than its progesterone-7alpha-ovalbumin analog (2-OVA) in the SPR-based assay, but with a conventional ELISA there was no significant difference between these two isomeric conjugates.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Christian Cook.