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Myles C. Dennis, Paul S.R. Goods, Martyn J. Binnie, Olivier Girard, Karen E. Wallman, Brian T. Dawson, and Peter Peeling

Purpose: This study aimed to assess the influence of graded air temperatures during repeated-sprint training in hypoxia (RSH) on performance and physiological responses. Methods: Ten well-trained athletes completed one familiarization and 4 experimental sessions at a simulated altitude of 3000 m (0.144 FIO2) above sea level. Air temperatures utilized across the 4 experimental sessions were 20°C, 25°C, 30°C, and 35°C (all 50% relative humidity). The participants performed 3 sets of 5 × 10 seconds “all-out” cycle sprints, with 20 seconds of active recovery between sprints and 5 minutes of active recovery between sets (recovery intensity = 120 W). Core temperature, skin temperature, pulse oxygen saturation, heart rate, rating of perceived exertion, and thermal sensation were collected. Results: There were no differences between conditions for peak power, mean power, and total work in each set (P > .05). There were no condition × time interaction effects for any variables tested. The peak core temperature was highest at 30°C (38.06°C [0.31°C]). Overall, the pulse oxygen saturation was higher at 35°C than at 20°C (P < .001; d < 0.8), 25°C (P < .001; d = 1.12 ± 0.54, large), and 30°C (P < .001; d = 0.84 ± 0.53, large). Conclusion: Manipulating air temperature between 20°C and 35°C had no effect on performance or core temperature during a typical RSH session. However, the pulse oxygen saturation was preserved at 35°C, which may not be a desirable outcome for RSH interventions. The application of increased levels of ambient heat may require a different approach if augmenting the RSH stimulus is the desired outcome.

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Valentin Bottollier, Matt R. Cross, Nicolas Coulmy, Loïc Le Quellec, and Jacques Prioux

Purpose: The purpose of this study was to determine the test–retest reliability of the 80s-slide-test in well-trained alpine ski racers. Methods: The sample consisted of 8 well-trained alpine ski racers (age = 17.8 [0.7] y old; height = 1.80 [0.09] m; body mass = 72.1 [9.5] kg) who performed a lab-based maximal graded test on cycle ergometer and three 80s-slide-tests in 4 separate sessions. The 80s-slide-test consisting of maximal push-offs performed for 80s on a 8-ft slide board. Oxygen uptake (V˙O2) and heart rate (HR) were recorded continuously. Blood lactate ([La]b) was determined immediately prerun, followed by 3 minutes postrun. Three minutes after the completion of the session, the subjects were asked to indicate their rate of perceived exertion using Borg scale ranging from 6 to 20. Total and every 10s mean push-offs number were assessed by camera. Typical errors of measurement, intraclass correlation coefficients, and smallest worthwhile change were calculated. Results: The 80s-slide-test showed strong reliability for total push-offs number, V˙O2peak, V˙O2mean, HRpeak, and HRmean. Δ[La]b, fatigue index, and the rate of perceived exertion were moderately reliable. Conclusion: The 80s-slide-test is a reliable test for well-trained alpine ski racers and can be used easily by trainers.

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Lee Baldock, Brendan Cropley, Rich Neil, and Stephen D. Mellalieu

The stress experiences and their impact upon the daily lives and mental well-being of English Premier League professional (soccer) football coaches were explored using an in-depth qualitative design. Eight participants were interviewed using a semi-structured approach with thematic and causal network analysis revealing that (a) a range of contextually dependent demands were experienced and interpreted in relation to their situational properties; (b) many demands were appraised and emotionally responded to in a negative manner; (c) a range of coping strategies were adopted to cope with stress experiences, with many reported as ineffective; and (d) stress experiences often led to negative implications for their daily lives and eudaimonic and hedonic well-being. Positive adaptations to some demands experienced were reported and augmented perceptions of mental well-being. The findings of this study make a novel and significant contribution to understanding the interrelationships between the principal components of the stress process and the prospective links between stress and mental well-being.

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Lewis King, Sarah Jane Cullen, Jean McArdle, Adrian McGoldrick, Jennifer Pugh, Giles Warrington, and Ciara Losty

The purpose of this study was to explore the sources of stress reported by professional jockeys. In total, 15 jockeys participated in semistructured interviews that included apprentice, conditional, and senior jockeys. Reflexive thematic analysis was used to analyze qualitative data that included inductive and deductive approaches. Jockeys reported a wide range of stress sources. Four core themes were identified and categorized as competitive (current form or being in a slump, pressure, horse, injury, opponents, tactical, and race day), racing industry (weight, workload, travel demands, injury concerns, suspension, and facilities), interpersonal (trainer, other jockeys, expectations of others, support networks, and communication), and career stressors (career uncertainty, career opportunities, and transitions). The findings highlight unique stressors to the jockey population, as well as stressors common with other athlete groups. Practical applied recommendations and future research directions are provided.

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Ed Maunder, Deborah K. Dulson, and David M. Shaw

Purpose: Considerable interindividual heterogeneity has been observed in endurance performance responses following induction of a ketogenic diet (KD). It is plausible that a physiological stress response in the period following the dramatic dietary shift associated with transition to a KD may explain this heterogeneity. Methods: In a randomized, crossover study design, 8 trained male runners completed an incremental exercise test and ran to exhaustion at 70%VO2max before and after a 31-day rigorously controlled habitual diet or KD intervention, and recorded heart rate variability (root mean square of the sum of successive differences in R–R intervals [rMSSD]) upon waking each morning along with the recovery–stress questionnaire for athletes each week. Data were analyzed using linear mixed models. Results: A significant reduction in rMSSD was observed in the KD (−9.77 [4.03] ms, P = .02), along with an increase in day-to-day variability in rMSSD (2.1% [1.0%], P = .03). The reduction in rMSSD in the KD for the subgroup of individuals exhibiting impaired exercise capacity following induction of the KD approached significance (Δ −22 [15] ms, P = .06, N = 4); whereas no effect was observed in those who exhibited unchanged exercise capacity (Δ 5 [18] ms, P = .61, N = 4). No main effects were observed for recovery–stress questionnaire for athletes. Conclusions: Our data suggest those working with endurance athletes transitioning onto a KD may consider using noninvasive, inexpensive resting heart rate variability measures to gain individual-level insights into the likely short-term effects on exercise capacity.

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Pedro L. Valenzuela, Fernando Rivas, and Guillermo Sánchez-Martínez

Purpose: To describe the effects of COVID-19 lockdown and a subsequent retraining on the training workloads, autonomic responses, and performance of a group of elite athletes. Methods: The training workloads and heart rate variability (assessed through the log-transformed root mean square of successive R–R intervals) of 7 elite badminton players were registered daily during 4 weeks of normal training (baseline), 7 to 10 weeks of lockdown, and 6 to 8 weeks of retraining. Physical performance was assessed at baseline and after each phase by means of a countermovement jump and the estimated squat 1-repetition maximum. Results: A reduction in training workloads was observed in all participants during the lockdown (−63.7%), which was accompanied by a reduced heart rate variability in all but one participant (−2.0%). A significant reduction was also observed for countermovement jump (−6.5%) and 1-repetition maximum performance (−11.5%), which decreased in all but one participant after the lockdown. However, after the retraining phase, all measures returned to similar values to those found at baseline. At the individual level, there were divergent responses, as exemplified by one athlete who attenuated the reduction in training workloads and increased her performance during the lockdown and another one who markedly reduced his workload and performance, and got injured during the retraining phase. Conclusions: Although there seems to be a large interindividual variability, COVID-19 lockdown is likely to impose negative consequences on elite athletes, but these detrimental effects might be avoided by attenuating reductions in training workloads and seem to be overall recovered after 6 to 8 weeks of retraining.

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Adam Mallett, Phillip Bellinger, Wim Derave, Katie McGibbon, Eline Lievens, Ben Kennedy, Hal Rice, and Clare Minahan

Purpose: To determine the influence of muscle fiber typology (MFT) on the pacing strategy of elite swimmers competing in the 200-m freestyle event. Method: The top 3 career-best performances from 25 elite 200-m freestyle swimmers were analyzed—12 women (1:58.0 [0:01.3] min:s) and 13 men (1:48.4 [0:02.5]). Muscle carnosine concentration was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and soleus muscles and expressed as a carnosine aggregate z score (CAZ score) relative to an age- and gender-matched nonathlete control group to estimate MFT. Linear regression models were employed to examine the influence of MFT on the percentage of overall race time spent in each 50-m lap. Results: Swimmers with a higher CAZ score spent a greater percentage of race time in lap 3 compared with swimmers with a lower CAZ score (0.1%, 0.0% to 0.2%; mean, 90% confidence interval, P = .02). For every 1% increase in the percentage of race time spent in lap 1, the percentage of race time spent in lap 3 decreased by 0.4% for swimmers with a higher CAZ score (0.2% to −0.5%, P = .00, r = −.51), but not for swimmers with a lower CAZ score (−0.1%, −0.3% to 0.1%, P = .28, r = −.18). The percentage of race time spent in lap 4 decreased by 0.8% for higher-CAZ-score swimmers (−0.5% to −1.0%, P = .00, r = −.66) and by 0.9% for lower-CAZ-score swimmers (−0.6% to −1.3%, P = .00, r = −.65) when lap 1 percentage increased by 1%. Conclusion: MFT may influence the pacing strategy of swimmers in the 200-m freestyle event, which provides an avenue for maximizing individualized pacing strategies of elite swimmers.

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Filippo Dolci, Andrew E. Kilding, Tania Spiteri, Paola Chivers, Ben Piggott, Andrew Maiorana, and Nicolas H. Hart

Purpose: To investigate the acute effect of repeated-sprint activity (RSA) on change-of-direction economy (assessed using shuttle running economy [SRE]) in soccer players and explore neuromuscular and cardiorespiratory characteristics that may modulate this effect. Methods: Eleven young elite male soccer players (18.5 [1.4] y old) were tested on 2 different days during a 2-week period in their preseason. On day 1, lower-body stiffness, power and force were assessed via countermovement jumps, followed by an incremental treadmill test to exhaustion to measure maximal aerobic capacity. On day 2, 2 SRE tests were performed before and after a repeated-sprint protocol with heart rate, minute ventilation, and blood lactate measured. Results: Pooled group analysis indicated no significant changes for SRE following RSA due to variability in individual responses, with a potentiation or impairment effect of up to 4.5% evident across soccer players. The SRE responses to RSA were significantly and largely correlated to players’ lower-body stiffness (r = .670; P = .024), and moderately (but not significantly) correlated to players’ force production (r = −.455; P = .237) and blood lactate after RSA (r = .327; P = .326). Conclusions: In summary, SRE response to RSA in elite male soccer players appears to be highly individual. Higher lower-body stiffness appears as a relevant physical contributor to preserve or improve SRE following RSA.

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Mehdi Kordi, Len Parker Simpson, Kevin Thomas, Stuart Goodall, Tom Maden-Wilkinson, Campbell Menzies, and Glyn Howatson

Purpose: To assess the association between the W′ and measures of neuromuscular function relating to the capacity of skeletal muscle to produce force in a group of elite cyclists. Methods: Twenty-two athletes specializing in a range of disciplines and competing internationally volunteered to participate. Athletes completed assessments of maximum voluntary torque (MVT), voluntary activation, and isometric maximum voluntary contraction to measure rate of torque development (RTD). This was followed by assessment of peak power output (PPO) and 3-, 5-, and 12-minute time trials to determine critical power. Pearson correlation was used to examine associations with critical power and W′. Goodness of fit was calculated, and significant relationships were included in a linear stepwise regression model. Results: Significant positive relationships were evident between W′ and MVT (r = .82), PPO (r = .70), and RTD at 200 milliseconds (r = .59) but not with RTD at 50 milliseconds and voluntary activation. Correlations were also observed between critical power and RTD at 200 milliseconds and MVT (r = .54 and r = .51, respectively) but not with PPO, voluntary activation, or RTD at 50 milliseconds. The regression analysis found that 87% of the variability in W′ (F 1,18 = 68.75; P < .001) was explained by 2 variables: MVT (81%) and PPO (6%). Conclusions: It is likely that muscle size and strength, as opposed to neural factors, contribute meaningfully to W′. These data can be used to establish training methods to enhance W′ to improve cycling performance in well-trained athletes.

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Karlee Naumann, Jocelyn Kernot, Gaynor Parfitt, Bethany Gower, and Kade Davison

The purpose of this study was to produce a descriptive overview of the types of water-based interventions for people with neurological disability, autism, and intellectual disability and to determine how outcomes have been evaluated. Literature was searched through MEDLINE, EMBASE, Ovid Emcare, SPORTDiscus, Google Scholar, and Google. One hundred fifty-three papers met the inclusion criteria, 115 hydrotherapy, 62 swimming, 18 SCUBA (self-contained underwater breathing apparatus), and 18 other water-based interventions. Common conditions included cerebral palsy, spinal cord injury, Parkinson’s disease, and intellectual disability. Fifty-four papers explored physical outcomes, 36 psychosocial outcomes, and 24 both physical and psychosocial outcomes, with 180 different outcome measures reported. Overall, there is a lack of high-quality evidence for all intervention types. This review provides a broad picture of water-based interventions and associated research. Future research, guided by this scoping review, will allow a greater understanding of the potential benefits for people with neurological disability, autism, and intellectual disability.