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Darren J. Paul, Paul S. Bradley and George P. Nassis

Time-motion analysis is a valuable data-collection technique used to quantify the match running performance of elite soccer players. However, interpreting the reductions in running performance in the 2nd half or temporarily after the most intense period of games is highly complex, as it could be attributed to physical or mental fatigue, pacing strategies, contextual factors, or a combination of mutually inclusive factors. Given that research in this domain typically uses a reductionist approach whereby match running performance is examined in isolation without integrating other factors, this ultimately leads to a 1-dimensional insight into match performance. Subsequently, a cohesive review of influencing factors does not yet exist. The aim of this commentary is to provide a detailed insight into the complexity of match running performance and its most influential factors.

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Stuart J. Cormack, Mitchell G. Mooney, Will Morgan and Michael R. McGuigan

Purpose:

To determine the impact of neuromuscular fatigue (NMF) assessed from variables obtained during a countermovement jump on exercise intensity measured with triaxial accelerometers (load per minute [LPM]) and the association between LPM and measures of running activity in elite Australian Football.

Methods:

Seventeen elite Australian Football players performed the Yo-Yo Intermittent Recovery Test level 2 (Yo-Yo IR2) and provided a baseline measure of NMF (flight time:contraction time [FT:CT]) from a countermovement jump before the season. Weekly samples of FT:CT, coaches’ rating of performance (votes), LPM, and percent contribution of the 3 vectors from the accelerometers in addition to high-speed-running meters per minute at >15 km/h and total distance relative to playing time (m/min) from matches were collected. Samples were divided into fatigued and nonfatigued groups based on reductions in FT:CT. Percent contributions of vectors to LPM were assessed to determine the likelihood of a meaningful difference between fatigued and nonfatigued groups. Pearson correlations were calculated to determine relationships between accelerometer vectors and running variables, votes, and Yo-Yo IR2 score.

Results:

Fatigue reduced the contribution of the vertical vector by (mean ± 90% CI) –5.8% ± 6.1% (86% likely) and the number of practically important correlations.

Conclusions:

NMF affects the contribution of individual vectors to total LPM, with a likely tendency toward more running at low speed and less acceleration. Fatigue appears to limit the influence of the aerobic and anaerobic qualities assessed via the Yo-Yo IR2 test on LPM and seems implicated in pacing.

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Brian Hanley

Purpose:

The aim of this study was to describe the pacing profiles used by racewalkers competing in IAAF World Championships.

Methods:

The times for each 5-km segment were obtained for 225 men competing over 20 km, 214 women competing over 20 km, and 232 men competing over 50 km, of whom 49 did not finish. Athletes were grouped based on finishing position (for medalists) or finishing time.

Results:

Different pacing profiles were used by athletes grouped by finishing time, with 20-km medalists using negative pacing and those finishing within 5% of the winning time matching the medalists’ early pace but failing to maintain it. Lower-placed 20-km athletes tended to start more quickly relative to personal-best pace and experienced significant decreases in pace later. Across all competitions, the fastest finishers started the slowest relative to previous best performance. All 50-km athletes slowed toward the finish, but lower-placed finishers tended to decrease pace earlier (with up to 60% of the race remaining). After halfway in the 50-km, 8 of the 15 athletes who had a 5-km split more than 15% slower than the previous split dropped out.

Conclusions:

The negative pacing profile used by 20-km medalists required the ability to start fast and maintain this pace, and similarly paced training may be beneficial in race preparation. Over 50 km, the tactic of starting slower than personal-best pace was generally less risky; nonetheless, any chosen pacing strategy should be based on individual strengths.

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Arturo Casado and Andrew Renfree

several studies have investigated pacing strategies in middle-distance (800 and 1500 m) running events, assessed through distribution of speeds over race segments, 2 – 4 other work has examined the influence of tactical positioning at intermediate points on finishing position. 5 Tactical issues are

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Maxime Deshayes, Corentin Clément-Guillotin and Raphaël Zory

of sex stereotype induction on physical performance for a task that does not require technical skill. We used an endurance task that can be encountered in daily life: a self-paced cycling task. In addition to recording power output during the cycling task, challenge appraisals were also investigated

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Pål Haugnes, Per-Øyvind Torvik, Gertjan Ettema, Jan Kocbach and Øyvind Sandbakk

’s pacing before entering the finish sprint leads to various degrees of fatigue. Due to the competition format in XC skiing sprint, the pacing utilized during heats and thereby the subsequent grade of fatigue at the finish sprint is decided both by each athlete’s choice of effort and the competition speed

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Roger Eston

The rating of perceived exertion (RPE) is a recognized marker of intensity and of homeostatic disturbance during exercise. It is typically monitored during exercise tests to complement other measures of intensity. The purpose of this commentary is to highlight the remarkable value of RPE as a psychophysiological integrator in adults. It can be used in such diverse fashions as to predict exercise capacity, assess changes in training status, and explain changes in pace and pacing strategy. In addition to using RPE to self-regulate exercise, a novel application of the intensity:RPE relationship is to clamp RPE at various levels to produce self-paced bouts of exercise, which can be used to assess maximal functional capacity. Research also shows that the rate of increase in RPE during self-paced competitive events of varying distance, or constant-load tasks where the participant exercises until volitional exhaustion, is proportional to the duration that remains. These findings suggest that the brain regulates RPE and performance in an anticipatory manner based on awareness of metabolic reserves at the start of an event and certainty of the anticipated end point. Changes in pace may be explained by a continuous internal negotiation of momentary RPE compared with a preplanned “ideal rate of RPE progression” template, which takes into account the portion of distance covered and the anticipated end point. These observations have led to the development of new techniques to analyze the complex relationship of RPE and pacing. The use of techniques to assess frontal-cortex activity will lead to further advances in understanding.

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Jason C. Tee, Mike I. Lambert and Yoga Coopoo

Purpose:

In team sports, fatigue is manifested by a self-regulated decrease in movement distance and intensity. There is currently limited information on the effect of fatigue on movement patterns in rugby union match play, particularly for players in different position groups (backs vs forwards). This study investigated the effect of different match periods on movement patterns of professional rugby union players.

Methods:

Global positioning system (GPS) data were collected from 46 professional match participations to determine temporal effects on movement patterns.

Results:

Total relative distance (m/min) was decreased in the 2nd half for both forwards (–13%, ±8%, ES = very likely large) and backs (–9%, ±7%, ES = very likely large). A larger reduction in high-intensity-running distance in the 2nd half was observed for forwards (–27%, ±16%, ES = very likely medium) than for backs (–10%, ±15%; ES = unclear). Similar patterns were observed for sprint (>6 m/s) frequency (forwards –29%, ±29%, ES = likely small vs backs –13% ±18%, ES = possibly small) and acceleration (>2.75 m/s2) frequency (forwards –27%, ±24%, ES = likely medium vs backs –5%, ±46%, ES = unclear). Analysis of 1st- and 2nd-half quartiles revealed differing pacing strategies for forwards and backs. Forwards display a “slow-positive” pacing strategy, while the pacing strategy of backs is “flat.”

Conclusions:

Forwards suffered progressively greater performance decrements over the course of the match, while backs were able to maintain performance intensity. These findings reflect differing physical demands, notably contact and running loads, of players in different positions.

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Margina Ruiter, Charly Eielts, Sofie Loyens and Fred Paas

seated rest and self-paced cycling on a desk bike in preadolescent children. The present study included several cognitive tests measuring cognitive control (ie, inhibition, visuospatial, and verbal working memory). On the basis of previous literature, it was expected that cognitive control was unaffected

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James J. McClain, Gregory J. Welk, Michelle Ihmels and Jodee Schaben

Background:

The PACER test is a valid and reliable assessment of aerobic capacity in children. However, many schools lack adequate space to administer the test. This study compared the utility of the standard 20m PACER test with an alternative 15m PACER protocol in 5th and 8th grade students.

Methods:

A total of 171 students completed both PACER protocols in a counterbalanced design. Agreement between the two protocols was assessed with correlations, repeated-measures ANOVA, and classification agreement into the FITNESSGRAM ® healthy fitness zones.

Results:

The difference in estimated VO2max between the two tests was slightly larger for boys (5th grade, 1.32 ml/kg/min; 8th grade, 1.72 ml/kg/min) than girls (5th grade, 0.14 ml/kg/min; 8th grade, 1.11 ml/kg/min), but these differences are probably not of practical significance. Classification agreement was 88% for boys and 91% for girls.

Conclusions:

Collectively, the results suggest that the 15m and 20m PACER provide similar information about aerobic fitness in youth. The 20m test is recommended when possible, but the 15m provides a useful alternative for schools with smaller gymnasiums.