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Lee Taylor, Christopher J. Stevens, Heidi R. Thornton, Nick Poulos and Bryna C.R. Chrismas

Purpose: To determine how a cooling vest worn during a warm-up could influence selected performance (countermovement jump [CMJ]), physical (global positioning system [GPS] metrics), and psychophysiological (body temperature and perceptual) variables. Methods : In a randomized, crossover design, 12 elite male World Rugby Sevens Series athletes completed an outdoor (wet bulb globe temperature 23–27°C) match-specific externally valid 30-min warm-up wearing a phase-change cooling vest (VEST) and without (CONTROL), on separate occasions 7 d apart. CMJ was assessed before and after the warm-up, with GPS indices and heart rate monitored during the warm-ups, while core temperature (T c; ingestible telemetric pill; n = 6) was recorded throughout the experimental period. Measures of thermal sensation (TS) and thermal comfort (TC) was obtained pre-warm-up and post-warm-up, with rating of perceived exertion (RPE) taken post-warm-ups. Results: Athletes in VEST had a lower ΔT c (mean [SD]: VEST = 1.3°C [0.1°C]; CONTROL = 2.0°C [0.2°C]) from pre-warm-up to post-warm-up (effect size; ±90% confidence limit: −1.54; ±0.62) and T c peak (mean [SD]: VEST = 37.8°C [0.3°C]; CONTROL = 38.5°C [0.3°C]) at the end of the warm-up (−1.59; ±0.64) compared with CONTROL. Athletes in VEST demonstrated a decrease in ΔTS (−1.59; ±0.72) and ΔTC (−1.63; ±0.73) pre-warm-up to post-warm-up, with a lower RPE post-warm-up (−1.01; ±0.46) than CONTROL. Changes in CMJ and GPS indices were trivial between conditions (effect size < 0.2). Conclusions: Wearing the vest prior to and during a warm-up can elicit favorable alterations in physiological (T c) and perceptual (TS, TC, and RPE) warm-up responses, without compromising the utilized warm-up characteristics or physical-performance measures.

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Ljudmila Zaletelj

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Josu Gomez-Ezeiza, Jordan Santos-Concejero, Jon Torres-Unda, Brian Hanley and Nicholas Tam

Purpose: To analyze the association between muscle activation patterns on oxygen cost of transport in elite race walkers over the entire gait waveform. Methods: A total of 21 Olympic race walkers performed overground walking trials at 14 km·h−1 where muscle activity of the gluteus maximus, adductor magnus, rectus femoris, biceps femoris, medial gastrocnemius, and tibialis anterior were recorded. Race walking economy was determined by performing an incremental treadmill test ending at 14 km·h−1. Results: This study found that more-economical race walkers exhibit greater gluteus maximus (P = .022, r = .716), biceps femoris (P = .011, r = .801), and medial gastrocnemius (P = .041, r = .662) activation prior to initial contact and weight acceptance. In addition, during the propulsive and the early swing phase, race walkers with higher activation of the rectus femoris (P = .021, r = .798) exhibited better race walking economy. Conclusions: This study suggests that the neuromuscular system is optimally coordinated through varying muscle activation to reduce the metabolic demand of race walking. These findings highlight the importance of proximal posterior muscle activation during initial contact and hip-flexor activation during early swing phase, which are associated with efficient energy transfer. Practically, race walking coaches may find this information useful in the development of specific training strategies on technique.

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Luana T. Rossato, Camila T.M. Fernandes, Públio F. Vieira, Flávia M.S. de Branco, Paula C. Nahas, Guilherme M. Puga and Erick P. de Oliveira

Background: Carbohydrate (CHO) mouth rinse has been used as an ergogenic strategy due to its central effect; however, the effects of this intervention during short-duration high-intensity exercises are not fully understood. Purpose: To investigate the effect of CHO mouth rinse on time to exhaustion in a short-duration high-intensity exercise performed on a treadmill. Methods: A randomized double-blind, placebo-controlled, crossover study was conducted with 10 (24.1 [4.3] y) recreationally active male runners. The protocol consisted of a warm-up at 65% of VO2max for 5 min followed by 3 min passive rest. At the end of this rest period, the individuals performed their mouth rinse either with CHO (maltodextrin, 6%) or with placebo (industrialized noncaloric juice with the same taste). Immediately after mouth rinse, the subjects ran at velocity equivalent to 100% of individual VO2max until voluntary exhaustion. The perceived effort was obtained through a Borg scale. Blood lactate was quantified before and after the protocol, and heart rate was evaluated during the protocol. Results: No difference was found (P = .90) in time to exhaustion between placebo (193.9 [46.5] s) and CHO mouth rinse (195.1 [51.8] s). Blood lactate, heart rate, and perception of effort increased in both groups, but with no differences (all variables, P > .05) between groups. Conclusion: The findings showed that a preexercise single-CHO mouth rinse was ineffective to improve running time to exhaustion at velocity equivalent to 100% VO2max on a treadmill in recreationally active male runners.

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Adam Douglas, Michael A. Rotondi, Joseph Baker, Veronica K. Jamnik and Alison K. Macpherson

Purpose: To compare on-ice external and internal training loads in world-class women’s ice hockey during training and competition. Methods: On-ice training loads were collected during 1 season from 25 world-class ice hockey players via wearable technology. A total of 105 on-ice sessions were recorded, which consisted of 61 training sessions and 44 matches. Paired and unpaired t tests compared training and competition data between and across playing positions. Results: For training data, there was a difference between positions for PlayerLoad (P < .001, effect size [ES] = 0.32), PlayerLoad·minute−1 (P < .001, ES = 0.55), explosive efforts (P < .001, ES = 0.63), and training impulse (P < .001, ES = 0.48). For the competition data, there were also differences between positions for PlayerLoad (P < .001, ES = 0.26), PlayerLoad·minute−1 (P < .001, ES = 0.38), explosive efforts (P < .001, ES = 0.64), and training impulse (P < .001, ES = 1.47). Similar results were found when positions were viewed independently; competition had greater load and intensity across both positions for PlayerLoad, training impulse, and explosive efforts (P < .001, ES = 1.59–2.98) and with PlayerLoad·minute−1 (P = .016, ES = 0.25) for the defense. Conclusions: There are clear differences in the volume and intensity of external and internal workloads between training and competition sessions. These differences were also evident when comparing the playing positions, with defense having lower outputs than forwards. These initial results can be used to design position-specific drills that replicate match demands for ice hockey athletes.

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Patrick Delisle-Houde, Nathan A. Chiarlitti, Ryan E.R. Reid and Ross E. Andersen

Purpose: To determine the predictability of common laboratory/field and novel laboratory tests for skating characteristics in Canadian college ice hockey players. Methods: A total of 18 male hockey players from the university’s varsity hockey team age 20–25 y (height 180.7 [6.4] cm, weight 87.1 [6.7] kg, and body fat 16.2% [4.0%]) completed common laboratory-/field-based testing (ie, standing long jump, vertical jump, off-ice proagility, V˙O2max, Wingate), novel laboratory-based testing (ie, Biodex dynamometer, dual-energy X-ray absorptiometry scan), and on-ice testing (ie, 30-m forward sprint, 30-m backward sprint, on-ice proagility). Results: Pearson correlations and stepwise regression revealed relationships between on-ice forward sprint and 4 off-ice tests (Wingate relative peak power [r = −.62, P < .01], standing long jump [r = −.45, P < .05], off-ice proagility left [r = .51, P < .05], and vertical jump impulse [r = .60, P < .01]). On-ice proagility left was correlated with off-ice proagility left (r = .47, P < .05), Wingate relative peak power (r = −.55, P < .01), and vertical jump impulse (r = −.53, P < .05). The 30-m backward skating test and the on-ice proagility right were not correlated with any off-ice test. Conclusion: Commonly used laboratory/field tests are effective in predicting 2 important primary abilities in ice hockey.

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Alison Keogh, Barry Smyth, Brian Caulfield, Aonghus Lawlor, Jakim Berndsen and Cailbhe Doherty

Purpose: Despite the volume of available literature focusing on marathon running and the prediction of performance, no single prediction equations exists that is accurate for all runners of varying experiences and abilities. Indeed the relative merits and utility of the existing equations remain unclear. Thus, the aim of this study was to collate, characterize, compare, and contrast all available marathon prediction equations. Methods: A systematic review was conducted to identify observational research studies outlining any kind of prediction algorithm for marathon performance. Results: Thirty-six studies with 114 equations were identified. Sixty-one equations were based on training and anthropometric variables, whereas 53 equations included variables that required laboratory tests and equipment. The accuracy of these equations was denoted via a variety of metrics; r 2 values were provided for 68 equations (r 2 = .10–.99), and an SEE was provided for 19 equations (SEE 0.27–27.4 min). Conclusion: Heterogeneity of the data precludes the identification of a single “best” equation. Important variables such as course gradient, sex, and expected weather conditions were often not included, and some widely used equations did not report the r 2 value. Runners should therefore be wary of relying on a single equation to predict their performance.

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Xihe Zhu and Justin A. Haegele

The purpose of this study was to examine reactivity to accelerometer measurement in children with visual impairments (VI), their sighted siblings, and their parents. A sample of 66 participants (including 22 children with VI, 22 siblings, and 22 parents) completed a demographic survey and wore triaxial accelerometers for at least 4 consecutive days for 8 hr. An analysis of covariances with repeated measures was conducted, controlling for participant gender. Children with VI had 8.1% less moderate to vigorous physical activity time on Day 1 than Days 2–4 average. Their sighted siblings and parents had 7.8% and 7.1% more moderate to vigorous physical activity time on Day 1 than their Days 2–4 average, respectively. The reactivity percentage for parents and children without VI is consistent with existing literature. However, an inverse reactivity for children with VI was found, which is a unique contribution to the literature and will have implications for researchers using accelerometers for this population.

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Wesley J. Wilson and K. Andrew R. Richards

Occupational socialization theory has been used to understand the recruitment, education, and socialization of physical education teachers for nearly 40 yr. It has, however, only recently been applied to the study of adapted physical education teachers. The purpose of this descriptive case study was to understand the socialization of preservice teachers in an adapted physical education teacher education graduate-level program. Participants included 17 purposefully selected preservice teachers (5 male and 12 female) enrolled in a yearlong graduate-level adapted physical education teacher education program. Qualitative data were collected using interviews, reflective journaling, and field notes taken during teaching and coursework observations. Data analysis resulted in the construction of 3 themes: overcoming contextual challenges to meet learners’ needs, the importance of field-based teacher education, and coping with the challenges of marginalization. The discussion connects to and advances occupational socialization theory in adapted physical education and suggests that professional socialization may have a more profound influence on preservice adapted physical education teachers than on their physical education counterparts.

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Dan Weaving, Clive Beggs, Nicholas Dalton-Barron, Ben Jones and Grant Abt

Purpose: To discuss the use of principal-component analysis (PCA) as a dimension-reduction and visualization tool to assist in decision making and communication when analyzing complex multivariate data sets associated with the training of athletes. Conclusions: Using PCA, it is possible to transform a data matrix into a set of orthogonal composite variables called principal components (PCs), with each PC being a linear weighted combination of the observed variables and with all PCs uncorrelated to each other. The benefit of transforming the data using PCA is that the first few PCs generally capture the majority of the information (ie, variance) contained in the observed data, with the first PC accounting for the highest amount of variance and each subsequent PC capturing less of the total information. Consequently, through PCA, it is possible to visualize complex data sets containing multiple variables on simple 2D scatterplots without any great loss of information, thereby making it much easier to convey complex information to coaches. In the future, athlete-monitoring companies should integrate PCA into their client packages to better support practitioners trying to overcome the challenges associated with multivariate data analysis and interpretation. In the interim, the authors present here an overview of PCA and associated R code to assist practitioners working in the field to integrate PCA into their athlete-monitoring process.