ORCID Profile
0000-0002-3393-1261
Current Organisations
Curtin University
,
RMIT University
,
Edith Cowan University
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Nanomaterials | Medical Devices | Nanotechnology | Sensor Technology (Chemical aspects)
Diagnostic Methods | Health Status (e.g. Indicators of Well-Being) |
Publisher: ACM
Date: 28-11-2016
Publisher: Informa UK Limited
Date: 24-03-2017
DOI: 10.1080/02701367.2017.1293777
Abstract: There is uncertainty as to which knee angle during a squat jump (SJ) produces maximal jump performance. Importantly, understanding this information will aid in determining appropriate ratios for assessment and monitoring of the explosive characteristics of athletes. This study compared SJ performance across different knee angles-90º, 100º, 110º, 120º, 130º, and a self-selected depth-for jump height and other kinetic characteristics. For comparison between SJ and an unconstrained dynamic movement, participants also performed a countermovement jump from a self-selected depth. Thirteen participants (M In the SJ, maximal jump height (35.4 ± 4.6 cm) was produced using a self-selected knee angle (98.7 ± 11.2°). Differences between 90°, 100°, and self-selected knee angles for jump height were trivial (ES ± 90% CL = 90°-100° 0.23 ± 0.12, 90°-SS -0.04 ± 0.12, 100°-SS -0.27 ± 0.20 0.5-2.4 cm) and not statistically different. Differences between all other knee angles for jump height ranged from 3.8 ± 2.0 cm (mean ± 90% CL) to 16.6 ± 2.2 cm. A similar outcome to jump height was observed for velocity, force relative to body weight, and impulse for the assessed knee angles. For young physically active adult men, the use of a self-selected depth in the SJ results in optimal performance and has only a trivial difference to a constrained knee angle of either 90° or 100°.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 10-2013
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2020
Publisher: Informa UK Limited
Date: 18-04-2016
DOI: 10.1080/02640414.2016.1175651
Abstract: Research indicates that instructing athlete's to focus on bodily movements (internal focus of attention [IFA]) may hinder performance, whereas instructing them to focus on the movement outcome (external focus of attention [EFA]) often enhances performance. Despite the importance of instructions in striking combat sports, limited research has examined the influence of IFA and EFA on performance in well-trained combat athletes. This study investigated the effects of different instructional cues on punching velocity (m · s
Publisher: Springer Science and Business Media LLC
Date: 2023
DOI: 10.1007/S00122-023-04272-7
Abstract: Map-based cloning, subcellular localization, virus-induced-gene-silencing and transcriptomic analysis reveal HvTUB8 as a candidate gene with pleiotropic effects on barley spike and leaf development via ethylene and chlorophyll metabolism. Barley lateral spikelet morphology and grain shape play key roles in grain physical quality and yield. Several genes and QTLs for these traits have been cloned or fine mapped previously. Here, we report the phenotypic and genotypic analysis of a barley mutant with round lateral spikelet (rls) from cv. Edamai 934. rls had round lateral spikelet, short but round grain, shortened awn, thick glume and dark green leaves. Histocytologic and ultrastructural analysis revealed that the difference of grain shape of rls was caused by change of cell arrangement in glume, and the dark leaf color resulted from enlarged chloroplast. HvTUBULIN8 ( HvTUB8 ) was identified as the candidate gene for rls by combination of RNA-Seq, map-based-cloning, virus-induced-gene-silencing (VIGS) and protein subcellular location. A single G-A substitution at the third exon of HvTUB8 resulted in change of Cysteine 354 to tyrosine. Furthermore, the mutant isoform Hvtub8 could be detected in both nucleus and cytoplasm, whereas the wild-type protein was only in cytoplasm and granular organelles of wheat protoplasts. Being consistent with the rare phenotype, the “A” allele of HvTUB8 was only detected in rls , but not in a worldwide barley germplasm panel with 400 accessions. VIGS confirmed that HvTUB8 was essential to maintain spike integrity. RNA-Seq results suggested that HvTUB8 may control spike morphogenesis via ethylene homeostasis and signaling, and control leaf color through chlorophyll metabolism. Collectively, our results support HvTUB8 as a candidate gene for barley spike and leaf morphology and provide insight of a novel mechanism of it in barley development.
Publisher: Frontiers Media SA
Date: 17-05-2018
Publisher: Informa UK Limited
Date: 04-06-2019
DOI: 10.1080/02640414.2018.1482526
Abstract: Prior research indicates that providing participants with positive augmented feedback tends to enhance motor learning and performance, whereas the opposite occurs with negative feedback. However, the majority of studies were conducted with untrained participants performing unfamiliar motor tasks and so it remains unclear if elite athletes completing familiar tasks respond in a similar fashion. Thus, this study investigated the effects of three different versions of false-performance feedback on punching force (N), pacing (force over time) and ratings of perceived exertion (RPE) in 15 elite amateur male boxers. Athletes completed a simulated boxing bout consisting of three rounds with 84 maximal effort punches delivered to a punching integrator on four separate days. Day one was a familiarisation session in which no feedback was provided. In the following three days athletes randomly received false-positive, false-negative and false-neutral feedback on their punching performance between each round. No statistical or meaningful differences were observed in punching forces, pacing or RPE between conditions (P > 0.05 ≤ 2%). These null results could stem from the elite status of the athletes involved, the focus on performance rather than learning, or they may indicate that false feedback has a less potent effect on performance than previously thought.
Publisher: Springer Science and Business Media LLC
Date: 02-09-2015
DOI: 10.1007/S00421-015-3249-Y
Abstract: Non-local muscle fatigue (NLMF) is characterized by muscle performance impairments in a contralateral or remote non-exercised muscle(s) following a fatiguing protocol of a different muscle group(s). This topic is of interest as it affords insights into physiological determinants of muscle fatigue and may provide practical applications concerning the order of exercises in training and rehabilitation programs. A literature review was conducted using Web of Science, PubMed, and Google Scholar databases to evaluate the NLMF effects and possible underlying mechanisms. Overall, 35 studies with 58 outcome measures that met the inclusion criteria were identified. The literature is conflicting with approximately half of the studies reporting NLMF effects (32 of 58 measurements). However, on closer examination 76% of outcome measures of the lower limbs reported NLMF effects (23 of 30 measurements) compared to only 32% in the upper body (9 of 28 measurements). Thus, it appears that NLMF effects may be muscle group dependent. Also, tests that involve prolonged or repetitive contractions provide clearer evidence of NLMF. Other variables potentially influencing the size of the NLMF effect include the fatigued muscle groups, the protocols used to elicit the fatigue, gender and training background of participants. While the NLMF literature is conflicting, certain variables appear to affect NLMF responses which can account for some of the discrepancies. Furthermore, the NLMF effects may be attributed to four different but interconnected pathways: neurological, biochemical, biomechanical and psychological.
Publisher: Canadian Science Publishing
Date: 03-2013
Abstract: To determine if post-activation potentiation (PAP) can augment sports performance, it is pertinent that researchers be confident that any enhancement in performance is attributable to the PAP phenomenon. However, obtaining mechanistic measures of PAP in the daily training environment of highly trained athletes is impractical. We sought to validate jump squats as a practical measure with ecological validity to sports performance against a mechanistic measure of PAP. We assessed the evoked muscle twitch properties of the knee extensors and jump squat kinetics of 8 physically trained males in response to a 5-repetition-maximum back squat conditioning stimulus (CS). Evoked muscle twitch, followed by 3 jump squats, was assessed before and at 4, 8, and 12 min post CS. Time intervals were assessed on separate occasions using a Latin square design. Linear regression was used to determine the relationship between post–pre changes in kinetic variables and muscle twitch peak force (Ft) and twitch rate of force development (RFDt). Large correlations were observed for both concentric relative and absolute mean power and Ft (r = 0.50 ± 0.30) and RFDt (r = 0.56 ± 0.27 and r = 0.58 ± 0.26). Concentric rate of force development (RFD) showed moderate correlations with Ft (r = 0.45 ± 0.33) and RFDt (r = 0.49 ± 0.32). Small-to-moderate correlations were observed for a number of kinetic variables (r = −0.42–0.43 ± 0.32–0.38). Jump squat concentric mean power and RFD are valid ecological measures of muscle potentiation, capable of detecting changes in athletic performance in response to the PAP phenomenon.
Publisher: Public Library of Science (PLoS)
Date: 10-07-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2018
DOI: 10.1519/JSC.0000000000002432
Abstract: Williams, KJ, Chapman, DW, Phillips, EJ, and Ball, N. Load-power relationship during a countermovement jump: A joint level analysis. J Strength Cond Res 32(4): 955–961, 2018—This study aimed to investigate whether hip, knee, and ankle peak power is influenced by the relative load lifted, altering the joint and system load-power relationship during a countermovement jump (CMJ). Twenty-three male national representative athletes (age: 20.3 ± 3.1 years, squat 1 repetition maximum [1RM]: 133.8 ± 24.8 kg) completed 3 CMJs at relative barbell loads of 0, 10, 20, 30, and 40% of an athlete's estimated back squat 1RM. Ground reaction force and joint kinematics were captured using a 16 camera motion capture array integrated with 2 in-ground triaxial force plates. Hip ( JOURNAL/jscr/04.03/00124278-201804000-00009/inline-formula1/v/2023-08-19T002751Z/r/image-tiff = 20%, range 0 40%), knee ( JOURNAL/jscr/04.03/00124278-201804000-00009/inline-formula2/v/2023-08-19T002751Z/r/image-tiff = 0%, 0 20%), and ankle ( JOURNAL/jscr/04.03/00124278-201804000-00009/inline-formula3/v/2023-08-19T002751Z/r/image-tiff = 40%, 0 40%) peak power was maximized at different percentages of absolute strength, with an athlete-dependent variation in load-power profiles observed across all lower-body joints. A decrease in system (body + barbell mass) peak power was significantly ( p ≤ 0.05, r = 0.45) correlated with a reduction in knee peak power. Timing of instantaneous system and hip peak power occurred significantly closer to toe-off as load increased. The findings highlight that the generation and translation of lower-body joint power is influenced by external load and athlete-dependent traits. This subsequently alters the load-power profile at a system level, explaining the broad spectrums of loads reported to optimize system power during a CMJ. When training, we recommend that a combination of barbell loads based on assorted percentages of the estimated 1RM be prescribed to optimize joint and system power during a CMJ.
Publisher: Springer Science and Business Media LLC
Date: 25-11-2020
DOI: 10.1038/S41586-020-2947-8
Abstract: Genetic ersity is key to crop improvement. Owing to pervasive genomic structural variation, a single reference genome assembly cannot capture the full complement of sequence ersity of a crop species (known as the ‘pan-genome’ 1 ). Multiple high-quality sequence assemblies are an indispensable component of a pan-genome infrastructure. Barley ( Hordeum vulgare L.) is an important cereal crop with a long history of cultivation that is adapted to a wide range of agro-climatic conditions 2 . Here we report the construction of chromosome-scale sequence assemblies for the genotypes of 20 varieties of barley—comprising landraces, cultivars and a wild barley—that were selected as representatives of global barley ersity. We catalogued genomic presence/absence variants and explored the use of structural variants for quantitative genetic analysis through whole-genome shotgun sequencing of 300 gene bank accessions. We discovered abundant large inversion polymorphisms and analysed in detail two inversions that are frequently found in current elite barley germplasm one is probably the product of mutation breeding and the other is tightly linked to a locus that is involved in the expansion of geographical range. This first-generation barley pan-genome makes previously hidden genetic variation accessible to genetic studies and breeding.
Publisher: Canadian Science Publishing
Date: 11-2015
Abstract: We sought to determine the efficacy of using a continuous time course trial to assess the temporal profile of post-activation potentiation and to determine the time course of potentiation of discrete jump squat kinetic and kinematic variables. Eight physically trained men performed jump squats before and 4, 8, and 12 min after a 5-repetition maximum back squat. Time intervals were assessed in 3 discontinuous trials (each time interval assessed in a separate trial) and in 1 continuous trial (all time intervals assessed in a single trial). Percentage differences between continuous and discontinuous trials at each time interval were mostly insubstantial. Discrete variables displayed a erse time course (effect size: trivial to large) time to maximal values ranged between 5.00 ± 2.53 min (concentric peak force) and 9.50 ± 2.98 min (eccentric mean force). Eccentric variables (8.58 ± 3.56 min) took longer to peak than concentric variables (6.64 ± 2.93 min) (effect size: small). In idual subjects attained maximal values for kinetic and kinematic variables at different time intervals, yet the 4-min interval typically displayed the greatest magnitude and frequency of potentiation. We conclude that a continuous time course trial does not substantially influence performance of subsequent jumps and is appropriate for determining the temporal profile of potentiation, which is influenced by discrete jump squat kinetic and kinematic variables and in idual differences.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2013
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2008
Publisher: SAGE Publications
Date: 03-2013
Abstract: The present study evaluated what are considered common and contentious differences in paddling technique within the surfing population, across the three distinct categories of: 1) Paddle Stroke length (Reach) 2) Torso Inclination (Chest Position) and 3) Arm Recovery. To assess the differences among paddling techniques, this study employed a within-subjects comparison of sprint paddling kinematic performance differences. Twenty competitive male surfers (19.1±6.8 years, 168.2±11.3 cm, 61.7±13.6 kg) performed 2 maximal trials each of Long vs. Short Reach, Chest Up vs. Down Position, and High vs. Low Arm Recovery during 15 m sprint paddle trials. The sprint paddle efforts were initiated from a stationary, prone lying position, using a horizontal position transducer attached to the rear waistline of each subjects' board-shorts such that kinematic data was obtained for 5 m, 10 m, and 15 m distances, and peak paddling velocity determined. There was no difference observed between Short and Long paddle strokes for any of the distance intervals, nor for peak paddling velocity (p .05). For chest position, the Down condition was found to be faster than the Chest Up position for all criterion variables (p=0.01–0.05), with moderate magnitude (d=0.25–0.43). The Low Arm Recovery resulted in superior performance compared to the High Arm Recovery (p=0.02–0.04), with low and moderate magnitudes (d=0.19–0.47). Sprint paddling is likely best conducted with the surfer's chest low to the board, without considerable extension through the back, and with a low arm recovery.
Publisher: IEEE
Date: 2008
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2015
Publisher: MDPI AG
Date: 02-12-2020
Abstract: The purpose of this study was to relate the shape of countermovement jump (CMJ) vertical ground reaction force waveforms to discrete parameters and determine if waveform shape could enhance CMJ analysis. Vertical ground reaction forces during CMJs were collected for 394 male and female collegiate athletes competing at the National Collegiate Athletic Association (NCAA) Division 1 and National Association of Intercollegiate Athletics (NAIA) levels. Jump parameters were calculated for each athlete and principal component analysis (PCA) was performed on normalized force-time waveforms consisting of the eccentric braking and concentric phases. A K-means clustering of PCA scores placed athletes into three groups based on their waveform shape. The overall average waveforms of all athletes in each cluster produced three distinct vertical ground reaction force waveform patterns. There were significant differences across clusters for all calculated jump parameters. Athletes with a rounded single hump shape jumped highest and quickest. Athletes with a plateau at the transition between the eccentric braking and concentric phase (amortization) followed by a peak in force near the end of the concentric phase had the lowest jump height and slowest jump time. Analysis of force-time waveform shape can identify differences in CMJ strategies in collegiate athletes.
Publisher: Wiley
Date: 18-11-2021
DOI: 10.1111/SMS.13866
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2009
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2011
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-04-2023
DOI: 10.1519/JSC.0000000000004428
Abstract: Horgan, BG, Tee, N, West, NP, Drinkwater, EJ, Halson, SL, Colomer, CME, Fonda, CJ, Tatham, J, Chapman, DW, and Haff, GG. Acute performance, daily well-being and hormone responses to water immersion after resistance exercise in junior international and subelite male volleyball athletes. J Strength Cond Res 37(8): 1643–1653, 2023—Athletes use postexercise hydrotherapy strategies to improve recovery and competition performance and to enhance adaptative responses to training. Using a randomized cross-over design, the acute effects of 3 postresistance exercise water immersion strategies on perceived recovery, neuromuscular performance, and hormone concentrations in junior international and subelite male volleyball athletes ( n = 18) were investigated. After resistance exercise, subjects randomly completed either 15-minute passive control (CON), contrast water therapy (CWT), cold (CWI), or hot water immersion (HWI) interventions. A treatment effect occurred after HWI reducing perceptions of fatigue (HWI CWT: p = 0.05, g = 0.43) improved sleep quality, compared with CON ( p 0.001, g = 1.15), CWI ( p = 0.017, g = 0.70), and CWT ( p = 0.018, g = 0.51) as well as increasing testosterone concentration (HWI CWT: p = 0.038, g = 0.24). There were trivial to small ( p 0.001–0.039, g = 0.02–0.34) improvements (treatment effect) in jump performance (i.e., squat jump and countermovement jump) after all water immersion strategies, as compared with CON, with high variability in the in idual responses. There were no significant differences (interaction effect, p 0.05) observed between the water immersion intervention strategies and CON in performance ( p = 0.153–0.99), hormone ( p = 0.207–0.938), nor perceptual ( p = 0.368–0.955) measures. To optimize recovery and performance responses, e.g., during an in-season competition phase, postresistance exercise HWI may assist with providing small-to-large improvements for up to 38 hours in perceived recovery (i.e., increased sleep quality and reduced fatigue) and increases in circulating testosterone concentration. Practitioners should consider in idual athlete neuromuscular performance responses when prescribing postexercise hydrotherapy. These findings apply to athletes who aim to improve their recovery status, where postresistance exercise HWI optimizes sleep quality and next-day perceptions of fatigue.
Publisher: Springer Science and Business Media LLC
Date: 28-08-2011
DOI: 10.1007/S00421-011-2134-6
Abstract: It is perceived that long haul travel, comprising of rapid movement across several time zones is detrimental to performance in elite athletes. However, available data is equivocal on the impact of long haul travel on maximal explosive movements. The aim of this study was to quantify the impact of long haul travel on lower body muscle performance. Five elite Australian skeleton athletes (1 M, 4 F) undertook long haul flight from Australia to Canada (LH(travel)), while seven national team Canadian skeleton athletes (1 M, 6 F) acted as controls (NO(travel)). Lower body power assessments were performed once per day between 09:30 and 11:00 h local time for 11 days. Lower body power tests comprised of box drop jumps, squat jump (SJ) and countermovement jumps (CMJ). The LH(travel) significantly decreased peak and mean SJ velocity but not CMJ velocity in the days following long haul flight. CMJ height but not SJ height decreased significantly in the LH(travel) group. The peak velocity, mean velocity and jump power eccentric utilisation ratio for the LH(travel) group all significantly increased 48 h after long haul flight. Anecdotally athletes perceived themselves as 'jet-lagged' and this corresponded with disturbances observed in 'one-off' daily jumping ability between 09:30 and 11:00 h after eastward long haul travel from Australia to North America when compared to non-travel and baseline controls.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2018
DOI: 10.1519/JSC.0000000000002249
Abstract: Barley, OR, Iredale, F, Chapman, DW, Hopper, A, and Abbiss, C. Repeat effort performance is reduced 24 hours after acute dehydration in mixed martial arts athletes. J Strength Cond Res 32(9): 2555–2561, 2018—This study sought to determine the influence of acute dehydration on physical performance and physiology in mixed martial arts (MMA). Mixed martial arts athletes ( n = 14 age: 23 ± 4 years) completed in a randomized counterbalanced order a dehydration protocol, (DHY: 3-hour cycling at 60 W in 40° C to induce 5% dehydration) or thermoneutral control (25° C: CONT) exercise, followed by ad libitum fluid/food intake. Performance testing (a repeat sled push test, medicine ball chest throw, and vertical jump) was completed 3 hours and 24 hours after the intervention, whereas urine and blood s les were collected before, 20 minutes, 3 hours, and 24 hours after the intervention. Body mass was reduced (4.8 ± 0.8%) after DHY ( p 0.001) and remained lower than CONT at 3 hours and 24 hours after DHY ( p = 0.003 and p = 0.024, respectively). Compared with CONT, average sled push times were slower 3 hours and 24 hours after DHY (19 ± 15% p = 0.001 g = 1.229 and 14 ± 15% p = 0.012 g = 0.671, respectively). When compared with the CONT, handgrip was weaker 3 hours after DHY (53 ± 8 and 51 ± 8 kg p = 0.044, g = 0.243, respectively) and medicine ball chest throw distances were shorter 24 hours after DHY (474 ± 52 and 449 ± 44 cm p = 0.016, g = 0.253, respectively). No significant differences were observed in vertical jump ( p = 0.467). Urine specific gravity was higher than CONT 20 minutes ( p = 0.035) and 24 hours ( p = 0.035) after DHY. Acute dehydration of 4.8% body mass results in reduced physical performance 3 and 24 hours after DHY. There is need for caution when athletes use dehydration for weight loss 24 hours before competition.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2020
Publisher: Public Library of Science (PLoS)
Date: 29-11-2016
Publisher: SAGE Publications
Date: 22-10-2021
Abstract: The purpose of this study was to investigate the influence of competition standard and player position on the physical demands of Australian elite youth male soccer players during match-play. Twenty-three elite youth male soccer players from the same Australian U17 National Centre of Excellence program were observed across 8 National Youth League (NYL) and 21 National Premier League (NPL) competition matches. Total (TD/min), low- ( 3.6 m/s), moderate- (3.6–5.0m/s) and high-speed ( 5.0 m/s) running distance, and the accelerations (Acc/min) (≥ 2.0 m/s 2 ) and decelerations (Dec/min) (≤ −2.0 m/s 2 ) were recorded using 15-Hz portable global positioning system tracking devices (GPSports, Canberra, Australia). An interaction was observed between competition standard and player position for TD/min ( p = 0.003), HSRD/min ( p = 0.007) and Acc/min ( p = 0.037) indicating the influence that competition standard had on these variables varied according to player position. Furthermore, we report that Central Defenders (3.1%), External Attackers (4.2%) and Central Attackers (3.8%) performed more TD/min in NYL (professional development level) compared to NPL (semi-professional) match-play. Central Defenders (24.2%) and Central Attackers (17.0%) completed more HSRD/min in NYL (professional development level) compared to NPL (semi-professional) match-play. Central Defenders (47.8%), External Defenders (20.5%), Midfielders (18.5%) and External Attackers (32.3%) all performed more Acc/min in NPL (semi-professional) when compared to NYL (professional development level) match-play. The results of this study provide scientific basis to aid the match-preparation of Australian elite youth male soccer player’s transition to higher standards of soccer.
Publisher: ACM
Date: 30-01-2023
Publisher: Georg Thieme Verlag KG
Date: 08-02-2011
Abstract: The purpose of this study was to examine whether time of day variations in power output can be accounted for by the diurnal fluctuations existent in body temperature. 8 recreationally trained males (29.8±5.2 yrs 178.3±5.2 cm 80.3±6.5 kg) were assessed on 4 occasions following a: (a) control warm-up at 8.00 am (b) control warm-up at 4.00 pm (c) extended warm-up at 8.00 am and, (d) extended warm-up at 4.00 pm. The control warm-up consisted of dynamic exercises and practice jumps. The extended warm-up incorporated a 20 min general warm-up on a stationary bike prior to completion of the control warm-up, resulting in a whole body temperature increase of 0.3±0.2°C. Kinetic and kinematic variables were measured using a linear optical encoder attached to a barbell during 6 loaded counter-movement jumps. Results were 2-6% higher in the afternoon control condition than morning control condition. No substantial performance differences were observed between the extended morning condition and afternoon control condition where body temperatures were similar. Results indicate that diurnal variation in whole body temperature may explain diurnal performance differences in explosive power output and associated variables. It is suggested that warm-up protocols designed to increase body temperature are beneficial in reducing diurnal differences in jump performance.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2018
Publisher: Springer International Publishing
Date: 2018
Publisher: Public Library of Science (PLoS)
Date: 28-02-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-2016
Publisher: BMJ
Date: 05-06-2008
Abstract: Surfing is a balance-reliant, open skill performed in a dynamic environment rich in visual, somatosensory and vestibular information. To evaluate adaptations to the postural control system by surfing experience. Postural control was assessed in an upright bipedal stance in 60 male volunteers (21 elite surfers, 20 intermediate level surfers, and 19 controls) using various closed-stance positions. Six tasks were performed with two trials including a cognitive task, in the following order: eyes open, head in a neutral position (EO1) eyes closed, head in a neutral position (EC) eyes closed, head back (ECHB) eyes open, head in a neutral position, cognitive task 1 (EOC1) eyes open head in a neutral position, cognitive task 2 (EOC2) eyes open head in a neutral position (EO2). Dependent variables were area of 95th centile ellipse (AoE) and sway path length (SPL). All participants showed systematic increases in SPL and AoE in EC and ECHB trials. Expert surfers displayed significantly (p<0.05) increased SPL but not AoE when sharing attention with both concurrent mental tasks compared with controls. Controls showed a slight, non-significant change in postural control (reduced SPL and AoE) when attending to concurrent mental tasks. The findings indicate that standard postural sway indices are not able to elucidate whether expertise in surfing facilitates adaptations to the postural control system. However, concurrent mental task findings illustrate that systematic differences in balance abilities between expert surfers and controls may exist.
Publisher: Springer Science and Business Media LLC
Date: 27-07-2016
DOI: 10.1007/S00426-016-0790-1
Abstract: While self-controlled practice has been shown to enhance motor learning with various populations and novel tasks, it remains unclear if such effects would be found with athletes completing familiar tasks. Study 1 used a single case-study design with a world-ch ion kickboxer. We investigated whether giving the athlete a choice over the order of punches would affect punching velocity and impact force. Separated by 1 min of rest, the athlete completed 2 rounds of 12 single, maximal effort punches (lead straight, rear straight, lead hook and rear hook) delivered to a punching integrator in a counterbalanced order over six testing days. In one round the punches were delivered in a predetermined order while in the second round the order was self-selected by the athlete. In the choice condition, the world ch ion punched with greater velocities (6-11 %) and impact forces (5-10 %). In Study 2, the same testing procedures were repeated with 13 amateur male kickboxers over 2 testing days. Similar to Study 1, the athletes punched with significantly greater velocities (6 %, p < 0.05) and normalised impact forces (2 %, p < 0.05) in the choice condition. These findings complement research on autonomy support in motor learning by demonstrating immediate advantages in force production and velocity with experienced athletes.
Publisher: Georg Thieme Verlag KG
Date: 08-2006
Abstract: Debate exists concerning the effect of contraction velocity on muscle damage, and few human studies have yet to address this issue. This study examined whether the velocity of eccentric exercise affected the magnitude of muscle damage. Twelve untrained subjects performed a series of slow velocity isokinetic eccentric elbow flexions (SV: 30 degrees . s (-1)) of one arm and a fast velocity exercise (FV: 210 degrees . s (-1)) of the other arm, separated by 14 days. In order to standardise the time under tension (120 s) for the two conditions, the number of muscle actions for SV was 30 and 210 for FV. Criterion measures consisted of maximal voluntary torque for isometric, concentric (4 velocities) and eccentric contractions (2 velocities), range of motion (ROM) and relaxed elbow joint angle (RANG), upper arm circumference, muscle soreness and plasma creatine kinase (CK) activity. Measures were taken before, immediately after, 0.5 hour and 24 - 168 hours (240 hours for CK) after each eccentric exercise protocol, and changes in the measures over time were compared between FV and SV by two-way repeated measures ANOVA. Both protocols resulted in significant decrements in isometric and dynamic torque (p < 0.01), but FV showed significantly (p < 0.05) greater reductions over time ( approximately 55 %) and a slower recovery compared to SV ( approximately 30 %). Significantly (p < 0.05) larger decreases in, and delayed recovery of, ROM and RANG were evident after FV compared to SV. FV had significantly (p < 0.05) larger increases in upper arm circumference and soreness compared to SV, and peak plasma CK activity was 4.5-fold greater (p < 0.05) following FV than SV. These results suggest that, for the same time under tension, fast velocity eccentric exercise causes greater muscle damage than slow velocity exercise in untrained subjects.
Publisher: Human Kinetics
Date: 03-2018
Abstract: Purpose : To explore the influence of body composition on thermal responses to cold-water immersion (CWI) and the recovery of exercise performance. Methods : Male subjects were stratified into 2 groups: low fat (LF n = 10) or high fat (HF n = 10). Subjects completed a high-intensity interval test (HIIT) on a cycle ergometer followed by a 15-min recovery intervention (control [CON] or CWI). Core temperature (T c ), skin temperature, and heart rate were recorded continuously. Performance was assessed at baseline, immediately post-HIIT, and 40 min postrecovery using a 4-min cycling time trial (TT), countermovement jump (CMJ), and isometric midthigh pull (IMTP). Perceptual measures (thermal sensation [TS], total quality of recovery [TQR], soreness, and fatigue) were also assessed. Results : T c and TS were significantly lower in LF than in HF from 10 min (T c, LF 36.5°C ± 0.5°C, HF 37.2°C ± 0.6°C TS, LF 2.3 ± 0.5 arbitrary units [a.u.], HF 3.0 ± 0.7 a.u.) to 40 min (T c , LF 36.1°C ± 0.6°C, HF 36.8°C ±0.7°C TS, LF 2.3 ± 0.6 a.u., HF 3.2 ± 0.7 a.u.) after CWI ( P .05). Recovery of TT performance was significantly enhanced after CWI in HF (10.3 ± 6.1%) compared with LF (3.1 ± 5.6%, P = .01) however, no differences were observed between HF (6.9% ±5.7%) and LF (5.4% ± 5.2%) with CON. No significant differences were observed between groups for CMJ, IMTP, TQR, soreness, or fatigue in either condition. Conclusion : Body composition influences the magnitude of T c change during and after CWI. In addition, CWI enhanced performance recovery in the HF group only. Therefore, body composition should be considered when planning CWI protocols to avoid overcooling and maximize performance recovery.
Publisher: BMJ
Date: 18-04-2008
Abstract: Large inter-subject variability in responses to eccentric exercise has been reported. This study investigated the hypothesis that the variability of changes in indirect markers of exercise-induced muscle damage (EIMD) would be explained by work performed and/or torque generated during eccentric exercise. Subjects (n = 53) performed 60 maximal eccentric actions of the elbow flexors on an isokinetic dynamometer that forcibly extended the elbow joint from 60 degrees to 180 degrees at a constant velocity (90 degrees s(-1)). Markers of EIMD included maximal voluntary isometric contraction torque at 90 degrees elbow flexion (MVC), range of motion, plasma creatine kinase activity and muscle soreness. Measurements were taken 2 days before, immediately after and 1-4 days post-exercise. Pearson's correlation coefficient was used to examine relationships between exercise parameters (total work, change in total work, torque produced during exercise, change in peak torque) and markers of EIMD. Large inter-subject variability was evident for both work and torque during exercise, and changes in all markers of EIMD. Contrary to the hypothesis, total work (normalised for in idual pre-exercise MVC) did not correlate significantly with any markers of EIMD, with the exception of MVC (r = 0.3). Total work performed and changes in total work showed higher correlations with some markers, but no r-values exceeded 0.4. Normalised exercise torque and the changes in peak torque during exercise were not correlated with changes in MVC, or other markers. These results suggest the large inter-subject variability in responses to eccentric exercise is not associated with work performed or torque generated during eccentric exercise.
Publisher: Frontiers Media SA
Date: 02-11-2018
Publisher: Springer International Publishing
Date: 2017
Publisher: Canadian Science Publishing
Date: 06-2006
DOI: 10.1139/H06-005
Abstract: This study tested the hypothesis that the magnitude of maximal isometric strength (MVC) loss immediately following eccentric exercise (MVC-post) would relate to changes in other indirect markers of muscle damage following exercise. Eighty-nine men were recruited from the same student population and performed 24 maximal eccentric actions of the elbow flexors. Commonly used markers of muscle damage such as relaxed and flexed elbow joint angles, range of motion (ROM), upper-arm circumference, muscle soreness, and plasma creatine kinase (CK) activity were measured before, immediately after, and 1-4 d after exercise. Pearson's product-moment correlation coefficients (r) between change in MVC-post and other markers of muscle damage, as well as MVC during recovery days, were calculated. Changes in MVC-post ranged from -72.8% to -17.6%, and correlated significantly (p 0.01) with MVC at 1 (r = 0.59), 2 (0.63), 3 (0.61), and 4 (0.62) d after exercise. Reduction in MVC-post also correlated significantly (p 0.05) with changes in relaxed (r = 0.50) and flexed elbow joint angles (-0.40), ROM (0.55), arm circumference (-0.45), peak palpation (-0.34) and extension muscle soreness (-0.48), and peak CK activity (-0.59). However, the r values were not necessarily high, and MVC-post poorly reflected the distribution of some measures, such as peak CK activity (124 - 50 440 IU·L -1 ). These results suggest that MVC-post is not a strong correlate of the changes in markers of muscle damage following eccentric exercise of the elbow flexors.Key words: maximal isometric strength, plasma CK activity, ROM, swelling, muscle soreness.
Publisher: Elsevier BV
Date: 07-2016
Publisher: Public Library of Science (PLoS)
Date: 08-2017
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2005
DOI: 10.1249/01.MSS.0000162691.66162.00
Abstract: This study investigated the hypothesis that maximal eccentric actions at a short muscle length would fail to confer a protective effect against muscle damage induced by maximal eccentric exercise at a long muscle length. Eleven males performed 24 maximal eccentric actions of the nondominant elbow flexors over a short extension range from an elbow joint angle of 0.87-1.74 rad (S-ECC) followed 4 wk later by eccentric actions at a long range of 2.27-3.14 rad (L-ECC). A second group of 11 males performed L-ECC on two occasions using the nondominant arm separated by 4 wk. Changes in maximal isometric strength, range of motion, upper arm circumference, muscle soreness, plasma creatine kinase and aspartate aminotransferase activities, and B-mode ultrasound images were compared between bouts and between groups by two-way repeated measures ANOVA. All measures changed significantly (P < 0.01) after the first bout however, the effects were significantly (P < 0.01) smaller after S-ECC compared with L-ECC. The second bout resulted in significantly (P < 0.01) reduced changes in all measures compared with the first bout in the subjects who performed L-ECC on both occasions. The subjects who performed S-ECC in the first bout displayed significantly smaller changes after L-ECC than those seen after L-ECC alone, with the degree of attenuation being around 50-70%. Contrary to the hypothesis, S-ECC provided partial but effective protection against L-ECC. This result suggests adaptations associated with the repeated bout effect were also produced after S-ECC, but the degree of adaptations was not as strong as that by L-ECC. Eccentric exercise at a short extension range can be used as a strategy to present severe muscle damage.
Publisher: Springer Nature Switzerland
Date: 2022
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2023
Publisher: Human Kinetics
Date: 02-2019
Abstract: Purpose : To examine the influence of fluid intake on heat acclimation and the subsequent effects on exercise performance following acute hypohydration. Methods : Participants were randomly assigned to 1 of 2 groups, either able to consume water ad libitum (n = 10 age 23 [3] y, height 1.81 [0.09] m, body mass 87 [13] kg HA W ) or not allowed fluid (n = 10 age 26 [5] y, height 1.76 [0.05] m, body mass 79 [10] kg HA NW ) throughout 12 × 1.5-h passive heat-acclimation sessions. Experimental trials were completed on 2 occasions before (2 baseline trials) and 1 following the heat-acclimation sessions. These sessions involved 3 h of passive heating (45°C, 38% relative humidity) to induce hypohydration followed by 3 h of ad libitum food and fluid intake after which participants performed a repeat sled-push test to assess physical performance. Urine and blood s les were collected before, immediately, and 3 h following hypohydration to assess hydration status. Mood was also assessed at the same time points. Results : No meaningful differences in physiological or performance variables were observed between HA NW and HA W at any time point. Using pooled data, mean sprint speed was significantly ( P .001) faster following heat acclimation (4.6 [0.7] s compared with 5.1 [0.8] s). Furthermore, heat acclimation appeared to improve mood following hypohydration. Conclusions : Results suggest that passive heat-acclimation protocols may be effective at improving short-duration repeat-effort performance following acute hypohydration.
Publisher: Informa UK Limited
Date: 10-2022
DOI: 10.1080/14763141.2019.1649715
Abstract: This investigation sought to quantify the level of measurement agreement in system force, velocity and power values derived across three commonly applied assessment techniques during a countermovement jump (CMJ). Twenty-five male national representative athletes completed three CMJs under unloaded (0%
Publisher: Human Kinetics
Date: 03-2016
Abstract: The purpose of this study was to calculate the coefficients of variation in jump performance for in idual participants in multiple trials over time to determine the extent to which there are real differences in the error of measurement between participants. The effect of training phase on measurement error was also investigated. Six subjects participated in a resistance-training intervention for 12 wk with mean power from a countermovement jump measured 6 d/wk. Using a mixed-model meta-analysis, differences between subjects, within-subject changes between training phases, and the mean error values during different phases of training were examined. Small, substantial factor differences of 1.11 were observed between subjects however, the finding was unclear based on the width of the confidence limits. The mean error was clearly higher during overload training than baseline training, by a factor of ×/÷ 1.3 (confidence limits 1.0–1.6). The random factor representing the interaction between subjects and training phases revealed further substantial differences of ×/÷ 1.2 (1.1–1.3), indicating that on average, the error of measurement in some subjects changes more than in others when overload training is introduced. The results from this study provide the first indication that within-subject variability in performance is substantially different between training phases and, possibly, different between in iduals. The implications of these findings for monitoring in iduals and estimating s le size are discussed.
Publisher: Human Kinetics
Date: 10-2015
Abstract: Initial short-track speed-skating 14-m start performance has substantial influence on 500-m race outcome at the international level, yet the relationship has not been systematically quantified. The purpose of this investigation was to examine the relationship between rank position entering first corner (RPEFC) and race outcome and to understand how this relationship changes with competition round and absolute race intensity. Data were compiled from 2011–2014 World Cup seasons and 2010 and 2014 Olympic Winter Games. Association between RPEFC and race outcome was determined through Kendall tau-rank correlations. A visual comparison was made of how the relationship changes with relative competition level (race tau correlations were sorted by competition round) and with race intensity (race tau correlations were sorted by within-event winning time). A very large relationship between RPEFC and race outcome was observed (correlations for cohort, τ = .60 men, τ = .53 women, τ = .67). When examined by competition round (quarter- to A-finals), no substantial change in relationship was observed (men, τ = .57–.46 women, τ = .73–.53). However, when the start–performance relationship was considered by within-event winning time, the relationship strength increased with decreasing time (men, τ = .61 to .46 women, τ = .76 to .57 fastest to 7th- and 8th-fastest combined, respectively). These results establish and quantify RPEFC as an important aspect of elite short-track 500-m race outcome. RPEFC as an indicator of race outcome becomes increasingly important with absolute race intensity, suggesting that RPEFC capability is a discriminating factor for competitors of similar top speed and speed endurance.
Publisher: Informa UK Limited
Date: 02-10-2015
DOI: 10.1080/14763141.2015.1084033
Abstract: Micro-sensors were used to quantify macro kinematics of classical cross-country skiing techniques and measure cycle rates and cycle lengths during on-snow training. Data were collected from seven national level participants skiing at two submaximal intensities while wearing a micro-sensor unit (MinimaxX™). Algorithms were developed identifying double poling (DP), diagonal striding (DS), kick-double poling (KDP), tucking (Tuck), and turning (Turn). Technique duration (T-time), cycle rates, and cycle counts were compared to video-derived data to assess system accuracy. There was good reliability between micro-sensor and video calculated cycle rates for DP, DS, and KDP, with small mean differences (Mdiff% = -0.2 ± 3.2, -1.5 ± 2.2 and -1.4 ± 6.2) and trivial to small effect sizes (ES = 0.20, 0.30 and 0.13). Very strong correlations were observed for DP, DS, and KDP for T-time (r = 0.87-0.99) and cycle count (r = 0.87-0.99), while mean values were under-reported by the micro-sensor. Incorrect Turn detection was a major factor in technique cycle misclassification. Data presented highlight the potential of automated ski technique classification in cross-country skiing research. With further refinement, this approach will allow many applied questions associated with pacing, fatigue, technique selection and power output during training and competition to be answered.
Publisher: Elsevier BV
Date: 2013
DOI: 10.1016/J.JSAMS.2012.05.006
Abstract: We tested the hypothesis that fast skeletal muscle troponin I (fsTnI) concentration in serum would increase more than those of slow skeletal muscle troponin I (ssTnI) after eccentric exercise of the elbow flexors using a sensitive blood marker to track fibre specific muscle damage. Observational comparison of response in a single experimental group. Eight young men (26.4±6.2 years) performed 210 (35 sets of 6) eccentric contractions of the elbow flexors on an isokinetic dynamometer with one arm. Changes in serum fsTnI and ssTnI concentrations, serum creatine kinase (CK) activity, and maximal voluntary isometric contraction torque (MVIC) before and 1, 2, 3, 4 and 14 days following exercise were analysed by a Student-Newman-Keuls multiple comparison test. The relationship between serum CK activity and fsTnI or ssTnI concentrations was determined using a Pearson's product moment correlation. Significant (P<0.05) decreases in MVIC and increases in serum CK activity and fsTnI were evident after exercise, but ssTnI did not change. The time course of changes in fsTnI was similar to that of CK, peaking at 4 days post-exercise, and the two were highly correlated (r=0.8). Increases in serum fsTnI concentrations reflect muscle damage, and it seems likely that only fast twitch fibres were damaged by eccentric contractions.
Publisher: Informa UK Limited
Date: 16-02-2016
DOI: 10.1080/02640414.2016.1143110
Abstract: This study aimed to (1) profile a professional boxer (23 years and 80 kg) with boxing-specific, muscle function, aerobic capacity and body composition tests, and (2) quantify how these measures varied during an 8-week preparation phase leading to, and post a state-Title Bout fought in the 76.2-kg class. A series of boxing-specific and muscle function tests were completed on 11 occasions: 9 prior and twice after the bout, each separated by approximately 2 weeks. The boxing test included 36 maximal punches (9 of each: lead and rear straights, lead and rear hooks) to a punching integrator measuring forces and velocity. Muscle function tests included countermovement jump, drop-jumps, isometric mid-thigh pull and isometric bench-press. Body composition was assessed using skin-fold measurements on three occasions and one dual energy X-ray absorptiometry scan. Aerobic capacity was assessed using 2 VO2 max tests. Leading up to the bout, performance decreased in isometric mid-thigh pull (8%), isometric bench-press (5%), countermovement jump (15%) and impact forces in 3 of 4 punches (4%-7%). Whereas measures of dynamic and isometric muscle function remained depressed or unchanged post competition, punching forces (6%-15%) and aerobic power (6%) increased. Data suggest the athlete may have super-compensated following rest as fatigue dissipated and further adaptation occurred.
Publisher: Wiley
Date: 03-08-2011
DOI: 10.1002/SEC.226
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.JSAMS.2019.03.010
Abstract: To explore the practicality of using functional principal components analysis (fPCA) and intra-athlete z-score changes for in idual athlete monitoring post-ACL injury and surgery. A single athlete case study using within-athlete repeated measures in the context of applied athlete monitoring. Using single leg (left) drop landing (3 landings per session) onto a force plate, the athlete completed 6 sessions prior (healthy) and 3 sessions post-ACL injury/surgery. Maximum vertical ground reaction force (vGRF), time to stabilisation (TTS) and outputs from fPCA (fPC scores) for the healthy sessions were used to develop intra-athlete means and standard deviations for each variable. Post-surgery measures were given z-scores relative to the healthy mean and standard deviation for each variable. The standard normal deviate (z = 1.96) was used as a threshold to flag landings that could be indicative of changes in movement behaviour. Maximum vGRF revealed no post-surgery trials that exceeded the standard normal deviate threshold based on the healthy data. TTS identified one landing post-surgery that exceeded the threshold. Scores for fPC2, fPC3 and fPC4 revealed landings that exceeded the threshold, with fPC4 demonstrating landings greater than the threshold for every trial (except two) post-surgery. Including fPCA identified significant and stable changes to the landing strategy (particularly within fPC4). When used in conjunction with other measures such as maximum vGRF and TTS, fPCA has the potential to provide meaningful insights into athlete monitoring models regarding changes to movement characteristics after injury.
Publisher: MDPI AG
Date: 21-05-2019
Abstract: In combat sports, athletes are ided into categories based on gender and body mass. Athletes attempt to compete against a lighter opponent by losing body mass prior to being weighed (i.e., ‘weight-cutting’). The purpose of this narrative review was to explore the current body of literature on weight-cutting and outline gaps for further research. Methods of weight-loss include energy intake restriction, total body fluid reduction and pseudo extreme/abusive medical practice (e.g., diuretics). The influence of weight-cutting on performance is unclear, with studies suggesting a negative or no effect. However, larger weight-cuts (~5% of body mass in h) do impair repeat-effort performance. It is unclear if the benefit from competing against a smaller opponent outweighs the observed reduction in physical capacity. Many mechanisms have been proposed for the observed reductions in performance, ranging from reduced glycogen availability to increased perceptions of fatigue. Athletes undertaking weight-cutting may be able to utilise strategies around glycogen, total body water and electrolyte replenishment to prepare for competition. Despite substantial discussion on managing weight-cutting in combat sports, no clear solution has been offered. Given the prevalence of weight-cutting, it is important to develop a deeper understanding of such practices so appropriate advice can be given.
Publisher: Elsevier BV
Date: 2011
DOI: 10.1016/J.JSAMS.2010.07.006
Abstract: Assisted jumping may be useful in training higher concentric movement speed in jumping, thereby potentially increasing the jumping abilities of athletes. The purpose of this study was to evaluate the effects of assisted jump training on counter-movement vertical jump (CMVJ) and spike jump (SPJ) ability in a group of elite male volleyball players. Seven junior national team volleyball players (18.0±1.0 yrs, 200.4±6.7 cm, and 84.0±7.2 kg) participated in this within-subjects cross-over counter-balanced training study. Assisted training involved 3 sessions per week of CMVJ training with 10 kg of assistance, applied through use of a bungee system, whilst normal jump training involved equated volume of unassisted counter-movement vertical jumps. Training periods were 5 weeks duration, with a 3-week wash-out separating them. Prior to and at the conclusion of each training period jump testing for CMVJ and SPJ height was conducted. Assisted jump training resulted in gains of 2.7±0.7 cm (p<0.01, ES=0.21) and 4.6±2.6 cm (p<0.01, ES=0.32) for the CMVJ and SPJ respectively, whilst normal jump training did not result in significant gains for either CMVJ or SPJ (p=0.09 and p=0.51 respectively). The changes associated with normal jump training and assisted jump training revealed significant differences in both CMVJ and SPJ (p=<0.03) in favour of the assisted jump condition, with large effect (CMVJ, ES=1.22 SPJ, ES=1.31). Assisted jumping may promote the leg extensor musculature to undergo a more rapid rate of shortening, and chronic exposure appears to improve jumping ability.
Publisher: Universidad de Alicante Servicio de Publicaciones
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 27-06-2008
DOI: 10.1007/S00421-008-0806-7
Abstract: Controversy exists concerning the susceptibility of elderly in iduals to eccentric exercise-induced muscle damage. This study investigated the hypothesis that muscle damage induced by fast maximal lengthening contractions would be greater for old than young men. Ten old (64 +/- 4 years) and young (25 +/- 6 years) men performed 30 maximal voluntary lengthening contractions of the elbow flexors at an angular velocity of 210 degrees s(-1). Prior to exercise, no significant differences were evident between groups for criterion measures. A significant (P < 0.05) group x time interaction was found only for isometric strength and muscle soreness with the old group showing significantly slower recovery of strength and less development of soreness compared with the young group. These results did not support the hypothesis that old men would be more susceptible to muscle damage, but confirmed a previous study reporting that recovery of muscle strength was slower for old than young in iduals.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 12-2012
Publisher: Elsevier BV
Date: 02-2007
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-2015
Publisher: Springer Science and Business Media LLC
Date: 25-10-2023
DOI: 10.1007/S00421-022-05075-2
Abstract: Following resistance exercise, uncertainty exists as to whether the regular application of cold water immersion attenuates lean muscle mass increases in athletes. The effects of repeated post-resistance exercise cold versus hot water immersion on body composition and neuromuscular jump performance responses in athletes were investigated. Male, academy Super Rugby players ( n = 18, 19.9 ± 1.5 y, 1.85 ± 0.06 m, 98.3 ± 10.7 kg) participated in a 12-week (4-week × 3-intervention, i.e., control [CON], cold [CWI] or hot [HWI] water immersion) resistance exercise programme, utilising a randomised cross-over pre–post-design. Body composition measures were collected using dual-energy X-ray absorptiometry prior to commencement and every fourth week thereafter. Neuromuscular squat (SJ) and counter-movement jump (CMJ) performance were measured weekly. Linear mixed-effects models were used to analyse main (treatment, time) and interaction effects. There were no changes in lean ( p = 0.960) nor fat mass ( p = 0.801) between interventions. CON ( p = 0.004) and CWI ( p = 0.003) increased ( g = 0.08–0.19) SJ height, compared to HWI. There were no changes in CMJ height ( p = 0.482) between interventions. Repeated post-resistance exercise whole-body CWI or HWI does not attenuate (nor promote) increases in lean muscle mass in athletes. Post-resistance exercise CON or CWI results in trivial increases in SJ height, compared to HWI. During an in-season competition phase, our data support the continued use of post-resistance exercise whole-body CWI by athletes as a recovery strategy which does not attenuate body composition increases in lean muscle mass, while promoting trivial increases in neuromuscular concentric-only squat jump performance.
Publisher: Elsevier BV
Date: 2021
Publisher: Springer International Publishing
Date: 2016
Publisher: Elsevier BV
Date: 03-2013
DOI: 10.1016/J.JSAMS.2012.06.001
Abstract: Two common models to investigate the effect of interventions on muscle damage include using two groups in which one group receives an intervention while the other acts as control, and using contralateral limbs of one group. The latter model is based on the assumption that changes in markers of muscle damage are similar between limbs, but this has not been examined systematically. This study compared changes in muscle damage markers between dominant and non-dominant arms following maximal eccentric exercise of the elbow flexors. Eighteen men performed 60 maximal eccentric elbow flexions of each arm separated by 4 weeks with the order of testing between arms randomised. Maximal voluntary isometric torque, range of motion, upper arm circumference, plasma creatine kinase (CK) activity and muscle soreness before and for 7 days following exercise were compared between arms using two-way repeated measures ANOVA. No significant differences between arms were evident for any of the markers, but significant (P<0.05) differences between first and second bouts were evident for changes in strength, circumference and CK with smaller changes following the second bout. A poor correlation was found for the magnitude of changes in the markers between dominant and non-dominant arms, suggesting that responses to eccentric exercise were not necessarily the same between arms. These results show that the order affected the responses of dominant and non-dominant arms to the eccentric exercise however, the contralateral limb design appears to be usable if bout order is counterbalanced and randomised among participants.
Publisher: Elsevier BV
Date: 08-2005
Publisher: Human Kinetics
Date: 08-2018
Abstract: Context : Combat sports are typically ided into weight classes, and body-mass manipulation to reach a weight class is commonplace. Previous research suggests that weight loss practices in mixed martial arts (MMA) may be more extreme than in other combat sports. Purpose : To investigate the magnitude of weight loss and the prevalence of weight loss strategies in different combat sports. Methods : Competitors (N = 637) from Brazilian jiu-jitsu, boxing, judo, MMA, Muay Thai/kickboxing, taekwondo, and wrestling completed an online questionnaire seeking information regarding their weight loss practices. Results : Body-mass manipulation was commonly undertaken by all combat-sport athletes, with a particularly high incidence of gradual dieting, increased exercise, and fluid restriction. Skipping meals was higher in taekwondo and wrestling (84%) compared with the other combat sports (∼58%), whereas training in heated rooms and forced oral fluid loss (spitting) was higher in wrestling (83% and 47%, respectively) compared with other combat sports (∼45% and ∼19%, respectively). MMA athletes reported the highest usage of sauna (76%) and water loading (67%) while also reporting the second-highest use of training in rubber lastic suits (63%). Conclusions : Body-mass manipulation was present in all combat sports, with the prevalence and magnitude of acute weight loss greater in MMA. The incidence of and practices reported will help support staff be fully aware of the variety of methods these athletes and coaches may use to achieve weight loss. Additionally, the results could aid regulatory bodies in the further development of policies on weight cutting.
Publisher: IEEE
Date: 03-2016
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-2016
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2019
DOI: 10.1519/JSC.0000000000001892
Abstract: Haug, WB, Drinkwater, EJ, Cicero, NJ, Barthell, JA, and Chapman, DW. The impact of dry-land sprint start training on the short track speed skating start. J Strength Cond Res 33(2): 544–548, 2019—This investigation sought to determine the effects of dry-land sprint start training on short track speed skating (STSS) start performance. Nine highly trained short track athletes completed a control period of normal STSS training followed by a 4-week training intervention. Before and after the control and intervention periods, athletes performed 3 electronically timed dry-land and on-ice 14.43 m maximal sprint start efforts. The intervention consisted of 2 sprint sessions per week consisting of 9 electronically timed 14.43 m dry-land sprint starts in addition to normal STSS training. The control period resulted in no substantial change in on-ice start performance (mean Δ: −0.01 seconds, 95% confidence limit [CL]: −0.08 to 0.05 seconds effect size [ES]: −0.05 trivial) however, a small change was observed in dry-land start performance (mean Δ: −0.07 seconds, 95% CL: −0.13 to −0.02 seconds ES: −0.49). After brief specific dry-land sprint start training, a small improvement was observed in both on-ice (Mean Δ: −0.07 seconds, 95% CL: −0.13 to −0.01 seconds ES: −0.33) and dry-land (Mean Δ: −0.04 seconds, 95% CL: −0.09 to 0.00 seconds ES: −0.29) start performance. This investigation suggests that STSS start performance can be improved through a brief dry-land sprint start training program.
Publisher: Human Kinetics
Date: 11-2018
Abstract: Purpose : To establish the influence of athlete-dependent characteristics on the generation and timing of system and in idual joint powers during a countermovement jump (CMJ). Methods : Male national representative athletes from volleyball (n = 7), basketball (n = 6), and rugby (n = 7) performed a set of 3 CMJs at relative barbell loads of 0%, 10%, 20%, 30%, and 40% of absolute back-squat strength. Ground-reaction forces and joint kinematics were captured using a 16-camera motion-capture system integrated with 2 in-ground force plates. Limb lengths and cross-sectional areas were defined using 3-dimensional photonic scans. A repeated-measures analysis of variance determined the interaction between system and joint load–power profiles, whereas a multiregression analysis defined the explained variance of athlete-dependent characteristics on the load that maximized system power. Results : System and isolated hip, knee, and ankle peak powers were maximized across a spectrum of loads between and within sports power values were not significantly different across loads. A positive shift in the timing of hip and ankle peak powers corresponded to a significant ( P .05) positive shift in the timing of system peak power to occur closer to toe-off. An optimal 3-input combination of athlete-dependent characteristics accounted for 68% ( P .001) of the explained variance in the load that maximized system peak power. Conclusion : The load maximizing system power is athlete-dependent, with a mixture of training and heredity-related characteristics influencing CMJ load–power profiles. The authors recommend that a combination of relative loads be in idually prescribed to maximize the generation and translation of system CMJ power.
Publisher: Frontiers Media SA
Date: 05-03-2019
Publisher: ACM
Date: 08-12-2014
Publisher: Elsevier BV
Date: 02-2007
Publisher: MDPI AG
Date: 18-04-2012
DOI: 10.3390/S120405047
Start Date: 2010
End Date: 2013
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2022
End Date: 07-2027
Amount: $5,000,000.00
Funder: Australian Research Council
View Funded Activity