ORCID Profile
0000-0002-7305-1090
Current Organisation
Leeds Trinity University
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Publisher: Public Library of Science (PLoS)
Date: 12-09-2018
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.JSAMS.2011.12.006
Abstract: This study investigated the influence of carbohydrate supplementation on skill performance throughout exercise that replicates soccer match-play. Experimentation was conducted in a randomised, double-blind and cross-over study design. After familiarization, 15 professional academy soccer players completed a soccer match simulation incorporating passing, dribbling and shooting on two separate occasions. Participants received a 6% carbohydrate-electrolyte solution (CHO) or electrolyte solution (PL). Precision, success rate, ball speed and an overall index (speed-precision-success SPS) were determined for all skills. Blood s les were taken at rest, immediately before exercise, every 15 min during exercise (first half: 15, 30 and 45 min second half: 60, 75 and 90 min), and 10 min into the half time (half-time). Carbohydrate supplementation influenced shooting (time×treatment interaction: p<0.05), where CHO attenuated the decline in shot speed and SPS index. Supplementation did not affect passing or dribbling. Blood glucose responses to exercise were influenced by supplementation (time×treatment interaction: p<0.05), where concentrations were higher at 45 min and during half-time in CHO compared with PL. Blood glucose concentrations reduced by 30±1% between half-time and 60 min in CHO. Carbohydrate supplementation attenuated decrements in shooting performance during simulated soccer match-play however, further research is warranted to optimise carbohydrate supplementation regimes for high-intensity intermittent sports.
Publisher: Georg Thieme Verlag KG
Date: 06-04-2011
Abstract: This study compared the demands of a soccer match simulation (SMS) incorporating 90 min of soccer-specific movement with passing, dribbling and shooting skills with those of competitive match-play (match). 10 elite youth soccer players participated in SMS and match-play while ingesting fluid-electrolyte beverages. No differences existed between trials for mean HR (SMS, match: 158 ± 4 beats·min (-1), 160 ± 3 beats·min (-1) P = 0.587), peak HR (SMS, match: 197 ± 3 beats·min (-1), 197 ± 4 beats·min (-1) P = 0.935) and blood glucose concentrations (SMS, match: 4.5 ± 0.1 mmol·L (-1), 4.6 ± 0.2 mmol·L (-1) P = 0.170). Inter-trial coefficient of variation (with Bland and Altman limits of agreement) were 2.6% (-19.4-15.4 beats·min (-1)), 1.6% (-14.3-14.7 beats·min (-1)) and 5.0% (-0.9-0.7 mmol·L (-1)) for mean HR, peak HR and blood glucose concentrations. Although the pattern of blood lactate response was similar between trials, blood lactate concentrations were higher at 15 min in SMS when compared to match. Notably, blood glucose concentrations were depressed by 17 ± 4% and 19 ± 5% at 15 min after half-time during match-play and SMS, respectively. Time spent completing low-intensity, moderate-intensity and high-intensity activities were similar between trials ( P > 0.05). In conclusion, the SMS replicates the physiological demands of match-play while including technical actions.
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: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2015
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: 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: 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: 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: MDPI AG
Date: 17-11-2020
DOI: 10.3390/APP10228149
Abstract: Soccer players perform a variety of training drills to develop the physical, technical and tactical qualities required for match-play. The role of coaches in prescribing training suggests that players may not always meet physical targets set by conditioning staff. To quantify the physical outputs elicited by different training drill types, 183 professional soccer players were monitored over 8 seasons using Microelectromechanical Systems during normal training, yielding 65,825 drill observations [362 ± 341 observations·player−1]. Linear mixed models assessed the influence of drill type, head coach and playing position on physical output. Drills lasted ~14 min, eliciting total distances and high speed running of ~1000 m and 40 m, respectively. Conditioning drills elicited substantially greater relative high-speed running [18.8 ± 27.2 m.min−1] and Sprint [3.5 ± 9.4 m.min−1] distances than all other drill types. The proportion of training drill types used and external outputs elicited per drill were affected by the head coach. Midfielders recorded the highest total distance [77.3 ± 36.1 m.min] and PlayerLoad™ [8.29 ± 3.54] of any playing position, whilst the lowest outputs were recorded by goalkeepers. This study provides reference data for practitioners when seeking to manipulate training prescription to achieve physical output targets whilst also meeting the team’s technical and tactical objectives.
Publisher: Informa UK Limited
Date: 12-2012
Publisher: Springer Science and Business Media LLC
Date: 12-04-2014
DOI: 10.1007/S40279-014-0184-8
Abstract: The use of nutritional ergogenic aids in team sports such as soccer is now commonplace. Aligned with the primary aim of soccer, which is to score more goals than the opposition within the allotted time, the quality of performance of technical actions (i.e., skills) executed during soccer-specific exercise is likely to determine success. However, when seeking to maintain soccer skill performance, information about the efficacy of nutritional interventions is lacking and factors which might modulate the efficacy of such strategies are unclear. This review aimed (i) to systematically evaluate the current research that examines the efficacy of nutritional interventions on soccer skills, and (ii) to provide a qualitative commentary on factors that have the potential to modulate the efficacy of such strategies. Relevant databases (PubMed and SPORTDiscus) were searched up to and including 1 July, 2013 for studies that investigated the efficacy of acute nutritional interventions on soccer skill performances. Overall, 279 records were retrieved. Articles were sequentially excluded from the review based on specific criteria, being: (A) articles that did not report outcomes directly relating to skilled performances in soccer, (B) articles that examined the influence of interventions that were not nutritional in origin and/or were nutritional in origin but provided >3 hours before skill testing commenced, (C) articles that were review papers, and (D) post-acceptance withdrawal of articles methods from database. Articles were independently assessed for the quality of the methods employed based upon the Physiotherapy Evidence Database (PEDro) scale. Records achieving a minimum PEDro score of 5 out of 10 were included in this review. Qualitative appraisal of 13 articles was performed after the application of exclusion criteria and quality assurance processes. The majority (n = 8) of articles examined the influence of carbohydrates on technical performance whereas fewer studies investigated the influence of caffeine ingestion (n = 2) and fluid provision (n = 3). Findings were reported for a total of 171 participants and all but one of the included articles used cross-over study designs. Most participants (94 %) were male, highly trained (reported maximal aerobic capacity range 50-59 ml·kg(-1)·min(-1)) and exercised in temperate environments (reported temperature range 13-25 °C). Six of the eight studies reported that carbohydrates, consumed in the form of a 6-8 % solution of glucose, sucrose or maltodextrin at rates of 30-60 g·h(-1), enhanced at least one aspect of skilled performance over the duration of exercise (75-90 min). Although some evidence exists to support the consumption of caffeine (6 mg·kg(-1) body mass [BM]) and prescribed fluid to preserve skills performed during soccer-specific exercise, findings from the small number of included studies were inconsistent. The outcome measures and methods used to quantify skilled performance were not consistent across studies consequently, it was not possible to perform meta-analyses to produce pooled effect sizes in this review. The findings from this systematic review suggest that nutritional interventions, which provide carbohydrate, caffeine and fluid, have potential to preserve skills performed under conditions that induce soccer-specific fatigue. The weight of current evidence supports the consumption of carbohydrate, but is less conclusive with respect to caffeine and fluid provision. It is likely that the efficacy of a nutritional intervention will be modulated by factors including the dose consumed, the mode of administration, in idual responsiveness to the intervention and interactions with other physiological changes occurring during soccer-specific exercise. Consequently, these factors should be considered when using carbohydrates, caffeine and fluid provision to maintain skilled performances in soccer. Future research should seek to optimise the nutritional strategies employed to maintain technical performance throughout match-play.
Publisher: Public Library of Science (PLoS)
Date: 23-05-2014
Publisher: Informa UK Limited
Date: 11-2010
DOI: 10.1080/02640414.2010.511247
Abstract: In this study, we examined the reliability and construct validity of new soccer skills tests. Twenty soccer players (10 professional and 10 recreational) repeated trials of passing, shooting, and dribbling skills on different days. Passing and shooting skills required players to kick a moving ball, delivered at constant speed, towards one of four randomly determined targets. Dribbling required players to negotiate seven cones over 20 m. Each trial consisted of 28 passes, 8 shots, and 10 dribbles. Ball speed, precision, and success were determined for all tests using video analysis. Systematic bias was small (<9% in all measures) and all outcome measures were similar between trials. Test-retest reliability statistics were as follows: ball speed (passing, shooting, dribbling coefficient of variation [CV]: 6.5%, 6.9%, 2.4% ratio limits of agreement [RLOA]: 0.958 ×/÷ 1.091, 0.990 ×/÷ 1.107, 0.993 ×/÷ 1.039), precision (passing, shooting, dribbling CV: 10.0%, 23.5%, 4.6% RLOA: 0.956 ×/÷ 1.147, 1.030 ×/÷ 1.356, 1.000 ×/÷ 1.068), and success (passing, shooting, dribbling CV: 11.7%, 14.4%, 2.2% RLOA: 1.017 ×/÷ 1.191, 0.913 ×/÷ 1.265, 0.996 ×/÷ 1.035). Professional players performed better than recreational players in at least one outcome measure for all skills. These findings demonstrate the reliability and validity of new soccer skill protocols.
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: Elsevier BV
Date: 03-2014
DOI: 10.1016/J.JSAMS.2013.04.010
Abstract: This study compared the effects of three carbohydrate-hydration strategies on blood glucose concentration, exercise performance and hydration status throughout simulated soccer match-play. A randomized, double-blind and cross-over study design was employed. After familiarization, 14 recreational soccer players completed the soccer match simulation on three separate occasions. Participants consumed equal volumes of 9.6% carbohydrate-caffeine-electrolyte (∼ 6 mg/kg BW caffeine) solution with carbohydrate-electrolyte gels (H-CHO), 5.6% carbohydrate-electrolyte solution with electrolyte gels (CHO) or electrolyte solution and electrolyte gels (PL). Blood s les were taken at rest, immediately before exercise and every 15 min during exercise (first half: 15, 30, 45 min second half: 60, 75, 90 min). Supplementation influenced blood glucose concentration (time × treatment interaction: p<0.001) however, none of the supplementation regimes were effective in preventing a drop in blood glucose at 60 min. Mean sprint speed was 3 ± 1% faster in H-CHO when compared with PL (treatment: p=0.047). Supplementation caused a 2.3 ± 0.5% increase in plasma osmolality in H-CHO (p<0.001) without change in CHO or PL. Similarly, mean sodium concentrations were 2.1 ± 0.4% higher in H-CHO when compared with PL (p=0.006). Combining high carbohydrate availability with caffeine resulted in improved sprint performance and elevated blood glucose concentrations throughout the first half and at 90 min of exercise however, this supplementation strategy negatively influenced hydration status when compared with 5.6% carbohydrate-electrolyte and electrolyte solutions.
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: Informa UK Limited
Date: 02-03-2020
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: Public Library of Science (PLoS)
Date: 18-03-2015
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: 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: 10-2013
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: 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: Springer Science and Business Media LLC
Date: 10-06-2023
DOI: 10.1038/S42949-023-00113-0
Abstract: There is a growing recognition that responding to climate change necessitates urban adaptation. We sketch a transdisciplinary research effort, arguing that actionable research on urban adaptation needs to recognize the nature of cities as social networks embedded in physical space. Given the pace, scale and socioeconomic outcomes of urbanization in the Global South, the specificities and history of its cities must be central to the study of how well-known agglomeration effects can facilitate adaptation. The proposed effort calls for the co-creation of knowledge involving scientists and stakeholders, especially those historically excluded from the design and implementation of urban development policies.
Publisher: Journal of Athletic Training/NATA
Date: 08-2014
DOI: 10.4085/1062-6050-49.3.12
Abstract: The ingestion of carbohydrate (CHO) before and during exercise and at halftime is commonly recommended to soccer players for maintaining blood glucose concentrations throughout match play. However, an exercise-induced rebound glycemic response has been observed in the early stages of the second half of simulated soccer-specific exercise when CHO-electrolyte beverages were consumed regularly. Therefore, the metabolic effects of CHO beverage consumption throughout soccer match play remain unclear. To investigate the blood glucose and blood lactate responses to CHOs ingested before and during soccer match play. Crossover study. Applied research study. Ten male outfield academy soccer players (age = 15.6 ± 0.2 years, height = 1.74 ± 0.02 m, mass = 65.3 ± 1.9 kg, estimated maximal oxygen consumption = 58.4 ± 0.8 mL·kg−1·min−1). Players received a 6% CHO-electrolyte solution or an electrolyte (placebo) solution 2 hours before kickoff, before each half (within 10 minutes), and every 15 minutes throughout exercise. Blood s les were obtained at rest, every 15 minutes during the match (first half: 0–15, 15–30, and 30–45 minutes second half: 45–60, 60–75, and 75–90 minutes) and 10 minutes into the halftime break. Metabolic responses (blood glucose and blood lactate concentrations) and markers of exercise intensity (heart rate) were recorded. Supplementation influenced the blood glucose response to exercise (time × treatment interaction effect: P ≤ .05), such that glucose concentrations were higher at 30 to 45 minutes in the CHO than in the placebo condition. However, in the second half, blood glucose concentrations were similar between conditions because of transient reductions from peak values occurring in both trials at halftime. Blood lactate concentrations were elevated above those at rest in the first 15 minutes of exercise (time-of-s le effect: P & .001) and remained elevated throughout exercise. Supplementation did not influence the pattern of response (time × treatment interaction effect: P = .49). Ingestion of a 6% CHO-electrolyte beverage before and during soccer match play did not benefit blood glucose concentrations throughout the second half of exercise.
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: Springer Science and Business Media LLC
Date: 08-11-2019
DOI: 10.1007/S11625-019-00749-X
Abstract: Creating a just and sustainable planet will require not only small changes, but also systemic transformations in how humans relate to the planet and to each other, i.e., social–ecological transformations. We suggest there is a need for collaborative environments where experimentation with new configurations of social–ecological systems can occur, and we refer to these as transformative spaces. In this paper, we seek a better understanding of how to design and enable the creation of transformative spaces in a development context. We analyse nine case studies from a previous special issue on Designing Transformative Spaces that aimed to collect ex les of cutting-edge action-oriented research on transformations from the Global South. The analysis showed five design phases as being essential: Problem Definition Phase Operationalisation Phase Tactical Phase Outcome Phase and Reflection Phase. From this synthesis, we distilled five key messages that should be considered when designing research, including: (a) there are ethical dilemmas associated with creating a transformative space in a system (b) it is important to assess the readiness of the system for change before engaging in it (c) there is a need to balance between ‘safe’ and ‘safe-enough’ spaces for transformation (d) convening a transformative space requires an assemblage of erse methodological frameworks and tools and (e) transformative spaces can act as a starting point for institutionalising transformative change. Many researchers are now engaging in transdisciplinary transformations research, and are finding themselves at the knowledge–action interface contributing to transformative space-making. We hope that by analysing experiences from across different geographies we can contribute towards better understanding of how to navigate the processes needed for the urgent global transformations that are being called for to create a more equitable and sustainable planet Earth.
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: Springer Science and Business Media LLC
Date: 07-2011
DOI: 10.2165/11589130-000000000-00000
Abstract: The ability to maintain technical performances (i.e. skills) throughout soccer match-play is considered to be crucial in determining the outcome of competitive fixtures. Consequently, coaches dedicate a large proportion of time to practicing isolated skills, such as passing, shooting and dribbling. Unlike other elements that contribute to team-sport performances, it is unusual for coaches to use methods other than observations to assess changes resulting from technical training. Researchers have employed various tests to measure isolated soccer skills however, reliance on outcome measures that include number of contacts (ball juggling tasks), time (dribbling tasks) and points scored (criterion-based passing and shooting tests) means that the outcomes are difficult for coaches to interpret. Skill tests that use video-analysis techniques to measure ball speed, precision and success of soccer skills offer valid and reliable alternatives. Although equivocal results are published, skill performances can be affected by assorted factors that threaten homeostasis, including match-related fatigue, dehydration and reductions in blood glucose concentrations. While acknowledging methodological constraints associated with using skill tests with limited ecological validity and cognitive demands, the effects of these homeostatic disturbances might vary according to the type of skill being performed. Shooting performances appear most susceptible to deterioration after exercise. Strategies such as aerobic training, fluid-electrolyte provision and acute carbohydrate supplementation have been found to improve proficiency in technical actions performed after soccer-specific exercise. However, mechanisms that cause deterioration in skill during soccer-specific exercise remain to be fully elucidated and strategies to optimize technical performance throughout match-play are warranted.
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: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2012
Publisher: Public Library of Science (PLoS)
Date: 05-04-2018
Publisher: Public Library of Science (PLoS)
Date: 31-01-2019
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
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 Mark Russell.