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Changes of Whole-Body Power, Muscle Function, and Jump Performance With Prolonged Cycling to Exhaustion

Jordan P.R. McIntyre, Grant A. Mawston, and Simeon P. Cairns

Purpose:

To quantify how whole-body power, muscle-function, and jump-performance measures change during prolonged cycling and recovery and determine whether there are relationships between the different fatigue measures.

Methods:

Ten competitive or recreationally active male cyclists underwent repeated 20-min stages of prolonged cycling at 70% VO2peak until exhaustion. Whole-body peak power output (PPO) was assessed using an all-out 30-s sprint 17 min into each cycle stage. Ratings of perceived exertion (RPE) were recorded throughout. Isometric and isokinetic muscle-function tests were made between cycle stages, over ~6 min, and during 30-min recovery. Drop-jump measures were tested at exhaustion and during recovery.

Results:

PPO initially increased or was maintained in some subjects but fell to 81% of maximum at exhaustion. RPE was near maximal (18.7) at exhaustion, with the time to exhaustion related to the rate of rise of RPE. PPO first started to decline only when RPE exceeded 16 (ie, hard). Peak isometric and concentric isokinetic torque (180°/s) for the quadriceps fell to 86% and 83% of pretest at exhaustion, respectively. In contrast, the peak concentric isokinetic torque (180°/s) of the hamstrings increased by 10% before declining to 93% of maximum. Jump height fell to 92% of pretest at exhaustion and was correlated with the decline in PPO (r = .79). Muscle-function and jump-performance measures did not recover over the 30-min postexercise rest period.

Conclusions:

At exhaustion, whole-body power, muscle-function, and jump-performance measures had all fallen by 7–19%. PPO and drop-jump decrements were linearly correlated and are appropriate measures of maximal performance.

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Which Jump Variables Should Be Used to Assess Explosive Leg Muscle Function?

Warren Young, Stuart Cormack, and Michael Crichton

Purpose:

The main purpose of this study was to determine the relationships between countermovement jump (CMJ) variables and acceleration and maximum speed performance.

Methods:

Twenty-three elite Australian football players were tested on a CMJ, which yielded several kinematic and kinetic variables describing leg muscle function. A 40 m sprint was also conducted to assess acceleration (10 m time) and an estimate of maximum speed (fying 20 m time). Players from one Australian Football League (AFL) club were tested and Pearson correlations for CMJ variables and sprint performance were calculated.

Results:

Jump height, peak velocity, peak force, and peak power had less than 50% common variance, and therefore represented independent expressions of CMJ performance. Generally, the correlations between CMJ variables and sprinting performance were stronger for maximum speed (small to large effect sizes) than for acceleration (trivial to moderate sizes). The variable that produced the strongest correlation with acceleration was jump height (r = -0.430, P = .041) and with maximum speed was peak power/weight (r = -0.649, P = .001).

Conclusions:

The results indicate that if an integrated system comprising a position transducer and a force platform is available for CMJ assessment, jump height and peak power/weight are useful variables to describe leg muscle explosive function for athletes who perform sprints.

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To Jump or Cycle? Monitoring Neuromuscular Function in Rugby Union Players

Gregory Roe, Joshua Darrall-Jones, Kevin Till, Padraic Phibbs, Dale Read, Jonathon Weakley, and Ben Jones

Purpose:

To evaluate changes in performance of a 6-s cycle-ergometer test (CET) and countermovement jump (CMJ) during a 6-wk training block in professional rugby union players.

Methods:

Twelve young professional rugby union players performed 2 CETs and CMJs on the 1st and 4th mornings of every week before the commencement of daily training during a 6-wk training block. Standardized changes in the highest score of 2 CET and CMJ efforts were assessed using linear mixed modeling and magnitude-based inferences.

Results:

After increases in training load during wk 3 to 5, moderate decreases in CMJ peak and mean power and small decreases in flight time were observed during wk 5 and 6 that were very likely to almost certainly greater than the smallest worthwhile change (SWC), suggesting neuromuscular fatigue. However, only small decreases, possibly greater than the SWC, were observed in CET peak power. Changes in CMJ peak and mean power were moderately greater than in CET peak power during this period, while the difference between flight time and CET peak power was small.

Conclusion:

The greater weekly changes in CMJ metrics in comparison with CET may indicate differences in the capacities of these tests to measure training-induced lower-body neuromuscular fatigue in rugby union players. However, future research is needed to ascertain the specific modes of training that elicit changes in CMJ and CET to determine the efficacy of each test for monitoring neuromuscular function in rugby union players.

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Seasonal Analysis of Mucosal Immunological Function and Physical Demands in Professional Australian Rules Footballers

Sam Coad, Bon Gray, and Christopher McLellan

Purpose:

To assess match-to-match variations in salivary immunoglobulin A concentration ([s-IgA]) measured at 36 h postmatch throughout an Australian Football League (AFL) premiership season and to assess the trends between 36-h-postmatch [s-IgA] and match-play exercise workloads throughout the same season.

Methods:

Eighteen elite male AFL athletes (24 ± 4.2 y, 187.0 ± 7.1 cm, 87.0 ± 7.6 kg) were monitored on a weekly basis to determine total match-play exercise workloads and 36-h-postmatch [s-IgA] throughout 16 consecutive matches in an AFL premiership season. Global positioning systems (GPS) with integrated triaxial accelerometers were used to measure exercise workloads (PlayerLoad) during each AFL match. A linear mixed-model analyses was conducted for time-dependent changes in [s-IgA] and player load.

Results:

A significant main effect was found for longitudinal postmatch [s-IgA] data (F 16,240 = 3.78, P < .01) and PlayerLoad data (F 16,66 = 1.98, P = .03). For all matches after and including match 7, a substantial suppression trend in [s-IgA] 36-h-postmatch values was found compared with preseason baseline [s-IgA].

Conclusion:

The current study provides novel data regarding longitudinal trends in 36-h-postmatch [s-IgA] for AFL athletes. Results demonstrate that weekly in-season AFL match-play exercise workloads may result in delayed mucosal immunological recovery beyond 36 h postmatch. The inclusion of individual athlete-monitoring strategies of [s-IgA] may be advantageous in the detection of compromised postmatch mucosal immunological function for AFL athletes.

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Effect of Cold on Proprioception and Cognitive Function in Elite Alpine Skiers

Sebastien Racinais, Nadia Gaoua, Khouloud Mtibaa, Rodney Whiteley, Christophe Hautier, and Marine Alhammoud

Purpose:

To determine the effect of cold ambient conditions on proprioception and cognitive function in elite alpine skiers.

Methods:

22 high-level alpine skiers and 14 control participants performed a proprioceptive-acuity (active movement-extent discrimination) and a cognitive (planning task) test in cold (8°C) and temperate (24°C) ambient conditions.

Results:

All participants displayed an increase in thermal discomfort and the amount of negative affects in the cold environment (all P < .05). Average proprioceptive acuity was significantly better in the elite skiers (0.46° ± 0.12°) than in the control group (0.55° ± 0.12°) (P < .05) and was not affected by cold ambient conditions, except for a shift in the pattern of error (over- vs underestimation, P < .05). Cognitive performance was similar between elite skiers and control participants in temperate environments but decreased in the cold in the control group only (P < .05) becoming lower than in elite skiers (P < .05).

Conclusion:

Elite alpine skiers showed a significantly better proprioceptive acuity than a control population and were able to maintain their performance during a cognitive task in a cold environment.

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Vitamin C Supplementation and Salivary Immune Function Following Exercise-Heat Stress

Andres E. Carrillo, René J. L. Murphy, and Stephen S. Cheung

Purpose:

Prolonged physical exertion and environmental heat stress may elicit postexercise depression of immune cell function, increasing upper respiratory tract infection (URTI) susceptibility. We investigated the effects of acute and short-term vitamin C (VC) compared with placebo (PL) supplementation on URTI susceptibility, salivary immunoglobulin A (s-IgA), and cortisol responses in healthy individuals following prolonged exercise-heat stress.

Methods:

Twelve participants were randomized into the VC or PL group in a double-blind design. For 12 days, participants consumed 3 × 500 mg tablets of VC or PL per day, with testing completed at baseline, then following acute (1 d) and short-term (8 d) supplementation. Participants performed 120.1 ± 49.6 min of cycling at 54 ± 6% VO2max in a hot (34.8 ± 1.0°C and 13 ± 3% relative humidity) environment, with saliva samples collected at pre-, post-, and 72 h postexercise. Health logs specifying URTI symptoms were completed for 7 days postexercise.

Results:

A 2 × 3 × 3 mixed ANOVA with a post hoc Bonferroni correction factor revealed a significant linear trend in postexercise cortisol attenuation in the VC group, 21.7 ± 15.1 nmol/L (mean ± SD) at baseline, to 13.5 ± 10.0 at acute, to 7.6 ± 4.2 after short term (P = .032). No differences were detected in ratio of s-IgA to protein or URTI symptoms between groups.

Conclusions:

These data suggest that vitamin C supplementation can decrease postexercise cortisol in individuals performing exercise similar to that of a half-marathon or marathon in hot conditions. However, no changes in s-IgA and URTI were evident, possibly due to previous moderate training and reduced physical and psychological stress compared with athletes participating in ultramarathons.

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Effect of Different Repeated-High-Intensity-Effort Bouts on Subsequent Running, Skill Performance, and Neuromuscular Function

Rich D. Johnston, Tim J. Gabbett, David G. Jenkins, and Michael J. Speranza

Purpose:

To assess the impact of different repeated-high-intensity-effort (RHIE) bouts on player activity profiles, skill involvements, and neuromuscular fatigue during small-sided games.

Participants:

22 semiprofessional rugby league players (age 24.0 ± 1.8 y, body mass 95.6 ± 7.4 kg).

Methods:

During 4 testing sessions, they performed RHIE bouts that each differed in the combination of contact and running efforts, followed by a 5-min off-side small-sided game before performing a second bout of RHIE activity and another 5-min small-sided game. Global positioning system microtechnology and video recordings provided information on activity profiles and skill involvements. A countermovement jump and a plyometric push-up assessed changes in lower- and upper-body neuromuscular function after each session.

Results:

After running-dominant RHIE bouts, players maintained running intensities during both games. In the contact-dominant RHIE bouts, reductions in moderate-speed activity were observed from game 1 to game 2 (ES = –0.71 to –1.06). There was also moderately lower disposal efficiency across both games after contact-dominant RHIE activity compared with running-dominant activity (ES = 0.62–1.02). Greater reductions in lower-body fatigue occurred as RHIE bouts became more running dominant (ES = –0.01 to –1.36), whereas upper-body fatigue increased as RHIE bouts became more contact dominant (ES = –0.07 to –1.55).

Conclusions:

Physical contact causes reductions in running intensity and the quality of skill involvements during game-based activities. In addition, the neuromuscular fatigue experienced by players is specific to the activities performed.

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Effects of Foot-Strike Pattern on Neuromuscular Function During a Prolonged Graded Run

Gianluca Vernillo, Matheus Aguiar, Aldo Savoldelli, Aaron Martinez, Marlene Giandolini, Nicolas Horvais, W. Brent Edwards, and Guillaume Y. Millet

system drive, PF voluntary activation was assessed by twitch interpolation using superimposed and potentiated high-frequency doublets during and after maximal voluntary isometric contraction, respectively. 9 Changes to skeletal muscle function were assessed by changes in the amplitudes of potentiated

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Effect of Prior Fatiguing Sport-Specific Exercise on Field Hockey Passing Ability

Enzo Hollville, Vincent Le Croller, Yoshihiro Hirasawa, Rémi Husson, Giuseppe Rabita, and Franck Brocherie

cumulated sprint time was fit to a second-order polynomial function ( r 2  = .94, P  < .043; Figure  4 ). To further investigate this finding, an individual quadratic regression model was performed for each subject, which revealed that 80.0% of them fit the quadratic model (demonstrated a decrease in

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Neuromuscular Responses to Conditioned Soccer Sessions Assessed via GPS-Embedded Accelerometers: Insights Into Tactical Periodization

Martin Buchheit, Mathieu Lacome, Yannick Cholley, and Ben Michael Simpson

improve our understanding of how to best program these sessions within the training week. The aims of the present study were to (1) examine the reliability of field-based running-specific measures of neuromuscular function (vertical stiffness, impact force, and propulsion efficiency), assessed via GPS