The impact of a 40-min nap on neuromuscular fatigue profile and recovery following the 5-m shuttle run test.

This study aims to investigate the impact of a 40-min nap opportunity on perceived recovery, exertion, and maximal voluntary isometric contraction (MVIC) following the 5-m shuttle run test (5SRT), after 1 night of normal sleep. In a randomised, counterbalanced, cross-over design, 17 trained men (mean [SD] age 20 [3] years, height 173 [6] cm, body mass 68 [6] kg) performed a 5SRT under two conditions: a 40-min nap opportunity and no-nap condition. After both conditions, electromyography signals during a 5-s isometric knee extension were recorded before and immediately after the 5SRT. Two electrical nerve stimulations at the femoral nerve were measured during and after the MVIC. Force, voluntary activation level, M-wave amplitudes, potentiated twitch, and electromyography signals (root mean square) were measured during each MVIC. Perceived exertion was recorded after each repetition of the test and perceived recovery was determined after the end of the MVIC. Compared to the no-nap condition, the 40-min nap resulted in significant enhancements in both the highest distance (p < 0.01, Δ = +7.6%) and total distance (p < 0.01, Δ = +7.5%). Before and after exercise, values for MVIC, root mean square, M-wave amplitudes, and voluntary activation level were improved after the 40-min nap opportunity compared to no-nap condition (all p ≤ 0.01). Values for perceived exertion and recovery were improved after the 40-min nap opportunity in comparison with no-nap condition (p ≤ 0.01). A 40-min nap opportunity improved repeated high-intensity short-term maximal performance, perceived recovery, associated neuromuscular responses, and reduced perceived fatigue. Therefore, our findings suggest that central and peripheral processes are involved in the improvements of 5SRT performance after napping.

Menstrual cycle characteristics, perceived impact on performance, and barriers to communication: Perspectives of high-performance adolescent athletes in Singapore.

The purpose of this study was to examine the menstrual cycle (MC) characteristics, explore the impact on performance, and identify barriers to and facilitators of MC-related communication among high-performance female adolescent athletes in Singapore. Ninety athletes (15.4 ± 1.8 years) from multiple sports completed an online questionnaire. Eighty-four athletes were postmenarcheal (menarcheal age 11.9 ± 1.3 years), including two who were using an oral contraceptive pill (OCP). Secondary amenorrhea, current or history of, was self-reported in 16% of athletes. Sixty-two percent and 67% of non-OCP athletes perceived that the MC affected their ability to train and compete, respectively. Athletes preferred speaking to a parent (85%) and a female figure (67%) about MC-related concerns. Through thematic analysis, three barriers to communication were constructed: (1) pervasive menstrual stigma, (2) constraints of the training environment, and (3) the low value placed on MC-related conversations. Two facilitators of communication were constructed: (1) respect athletes' individual experiences as menstruating girls and (2) foster a safe space for MC-related conversations. Findings demonstrated that menstrual irregularities are common in adolescent athletes and screening for MC disorders, particularly primary amenorrhea should be undertaken in this population, with clear support pathways for management including symptom mitigation. To support athletes in raising MC-related concerns when needed, structured communication pathways that consider individual preferences and involve a (female) point of contact should be established within the training environment. Improving menstrual health literacy among adolescent athletes before any misinformation or negative perceptions are firmly established may contribute to longevity in their athletic careers.

The effectiveness of a short course to improve coaches' knowledge on considerations for female athletes.

This study aimed to assess the effectiveness of an online short course in improving the knowledge and confidence of coaching and support staff when working with female athletes. A mixed-methods survey design was used, where participants completed surveys pre-, post-, and 6 months following an 8-week online course. Qualitative responses were analysed inductively using thematic analysis based on two pre-identified themes. Of the 92 participants who completed both pre- and post-course surveys, 72% (n = 66) were female and 67% (n = 62) were from team sports. Perceived knowledge and confidence improved following the course (p < 0.001) and were above pre-course values 6-months post (p < 0.001). A-priori theme Course Expectations generated two sub-themes: 'Empowering [me] to empower and support [them]', and "Sharing knowledge and experiences". A-priori theme Changes in Practice had subthemes of "Relaxing into it" and "Embedding support structures". Participants indicated that they enjoyed learning from a variety of content experts as well as other participants in an online format. Future courses aimed at coaching/support staff should design and deliver accessible programs aligned with the learning preferences of these individuals. When delivering specific education regarding supporting female athletes, targeting and encouraging men to participate may be beneficial.

Effects of Sport-Specific Training Intensity on Sleep Patterns and Psychomotor Performance in Adolescent Athletes.

PURPOSE: Adolescent student-athletes face time constraints due to athletic and scholastic commitments, resulting in habitually shortened nocturnal sleep durations. However, there is a dearth of research on the effects of sleep debt on student-athlete performance. The study aimed to (i) examine the habitual sleep patterns (actigraphy) of high-level student-athletes during a week of training and academic activities, (ii) ascertain the effects of habitual sleep durations experienced by high-level student-athletes on psychomotor performance, and (iii) examine the impact of sport training intensities on the sleep patterns of high-level student-athletes that participate in low and high intensity sports. METHODS: Sleep patterns of 29 high-level student-athletes (14.7 ± 1.3 yrs) were monitored over 7 days. A psychomotor vigilance task was administered on weekdays to ascertain the effects of habitual sleep durations. RESULTS: Weekend total sleep time was longer than weekdays along with a delay in bedtime, and waketimes. Psychomotor vigilance reaction times on Monday were faster than on Thursday and Friday, with reaction times on Tuesday also faster than on Friday. False starts and lapses were greater on Friday compared with Monday. CONCLUSION: There was a negative impact of sleep debt on student-athletes' psychomotor performance.

Detecting and developing youth athlete potential: different strokes for different folks are warranted.

Sport talent identification and development (TI and TD) in youth continues to attract strong interest among coaches, sport scientists and sport administrators. TI for sport in youth with the anticipation of future elite level sport achievement is both an art and a science, and is strongly influenced by within athlete and extraneous-to-athlete factors (ecosystem of support or the lack of). The returns from investment on current TI and TD models of sport in youth are subpar in that few continue in the sport to achieve podium positions at the elite sport level in adulthood. Why, where and how one succeeds in sport, and what that success means to the athlete and stakeholders are dependent on the culture and context of the country. We advocate harnessing the power of sport to help in youth development, to be holistic in its nurturance, to allow for individual idiosyncratic expressions of the athletes, to provide for talent transfer across sport, and to facilitate key stakeholders to 'join' hands to work for the common interest and understanding for as many youth and adults so as to provide them with opportunities through support and coaching to compete at the different levels of competition in sport. Governments, policy makers and administrators of sport must decide, within their specific circumstances, if TI and TD in sport in youth is serving a meaningful purpose and is a viable return on investment; in short, is it mission possible or is it… a quest for the Holy Grail for a podium finish in elite level sport competition?

Higher Levels of Morning and Daytime Light Exposure Associated with Positive Sleep Indices in Professional Team Sport Athletes.

Objective: Light exposure techniques have been recommended to combat sleep issues caused by disruption to circadian regularity in the athletic population, although studies are lacking. Methods: A total of 17 professional male Australian Football athletes (age ± SD: 22 ± 3 years) wore a wrist actigraph to measure sleep parameters, and a wearable light sensor to measure melanopic equivalent daylight illuminance (mEDI, in lux) for 14 days. Participants completed three sleep questionnaires at the end of the data collection period and completed well-being surveys 6 times. The Sleep Regularity Index (SRI) for each player was also calculated from actigraphy data. Light exposure data were organised into three different timeframes: morning (wake time + 2 hours), daytime (end of morning to 6 pm), and evening (2 hours leading up to bedtime) for analysis. Repeated measures correlation was conducted for objective sleep measures and mEDI values per timeframe. Pearson's correlation was conducted on subjective sleep measures and well-being measures against mEDI values per timeframe. Results: Higher morning light was associated with significantly (p < 0.001) greater total sleep time (r = 0.31). Higher daytime light exposure was associated with higher subjective sleep quality (r = 0.48, p < 0.05). Higher evening light exposure was associated with higher Athlete Sleep Screening Questionnaire (ASSQ) global scores (r = 0.52, p < 0.05). There were no other significant correlations between light exposure and sleep or well-being measures (p > 0.05). Conclusion: Higher morning and daylight exposure levels were associated with various positive objective and subjective sleep measures in professional team sport athletes, supporting the need for education on optimising light exposure to improve circadian function, sleep, and health.

Sink or Swim? Sleep Patterns in Highly Trained Adolescent Swimmers during the In-Season Phase of Training.

Objectives The aim of this study was to investigate the sleeping patterns of highly-trained adolescent swimmers. Further objectives were to compare subjective and objective measures of sleep and to evaluate the relationship between electronic device use and sleep in this cohort. Methods Fifteen national-level swimmers (age: 16.4 ± 1.0 years) wore wrist actigraphs while completing sleep diaries over a two-week training period. Types of nights were classified as early morning training (≤7am - EARLY), day training (>7am - DAY), and no training (REST). Information on electronic device use before bed and other sleep behaviors was collected via questionnaires. Results Total sleep time (TST) was significantly ( p < 0.05) shorter on nights preceding EARLY (5:53 ± 1:06 hour:min) compared with nights preceding DAY (7:40 ± 1:12 hour:min) and REST (7:59 ± 1:19 hour:min). Participants overestimated subjective TST by ∼54 minutes when compared with objectively measured TST ( p < 0.05). Discussion Adolescent athletes obtained a greater amount of sleep prior to later training the next day or before rest days, when compared with early morning swim training the next day. Adolescents also overestimated their sleep duration by ∼1 hour per night. There were no significant relationships between electronic device use at night and measured sleep indices.

The acute effects of nonsleep deep rest on perceptual responses, physical, and cognitive performance in physically active participants.

This study aimed to examine the effect of nonsleep deep rest (NSDR) on physical and cognitive performance, as well as sleepiness, acute readiness, recovery, stress, and mood state in physically active participants. A total of 65 physically active participants (42 male, 23 female) were randomly assigned into two groups: an experimental group (NSDR, n = 34), in which participants completed a 10-min NSDR intervention, and a control group (CON, n = 31), whereby participants sat passively for 10 min. Testing measures were assessed immediately pre and 10 min post each condition and comprised completing a hand grip strength dynamometer test and a countermovement jump test on force plates, cognitive function measures via a psychomotor vigilance task (PVT-B), and a Simon task test, along with four questionnaires to assess sleep, recovery, and mood state. A significant Group × Time interaction favored the NSDR condition for handgrip strength, median reaction time during the PVT-B, and accuracy percentage during the Simon task. Questionnaire responses demonstrated NSDR to be associated with significant benefits to physical readiness, emotional balance, overall recovery, negative emotional state, overall stress, and tension in comparison to CON (p < .05). The NSDR intervention could be a valuable strategy for acutely enhancing overall well-being and readiness.

Routine, Routine, Routine: Sleep Regularity and its Association with Sleep Metrics in Professional Rugby Union Athletes.

BACKGROUND: Maintaining a consistent sleep and wake time is often reported as a key component of circadian rhythmicity and quality sleep. However, the impact of sleep onset and offset time variability on overall sleep outcomes are underreported in elite athlete populations. This study investigated the relationship between sleep onset and offset time variability using the sleep regularity index (SRI) and measures of sleep and well-being in professional rugby union athletes. Twenty-three professional male rugby union athletes (mean ± SD, age: 23 ± 3 y) underwent sleep monitoring via wrist actigraphy for three weeks during a pre-season phase of training and completed a daily wellness questionnaire. Median SRI was calculated and used to stratify the trainees into two quantile groups: >76.4 SRI (Regular, n = 11) and < 76.4 SRI (Irregular, n = 12). RESULTS: The regular sleep group showed significantly longer total sleep duration (p = 0.02, d = 0.97) compared to the irregular group (7:42 ± 0:29 vs. 7:18 ± 0:20 h: min per night, respectively). Furthermore, while not statistically significant, the regular sleep group showed greater sleep efficiency and less wake episodes compared to irregular sleepers, as demonstrated by moderate effect sizes (d = 0.71 and 0.69, respectively). CONCLUSIONS: The results from this study indicate that minimizing variability in sleep onset and offset time is beneficial for increasing sleep duration and may improve sleep efficiency during pre-season training in elite male rugby union athletes. This study provides evidence for the importance of including sleep-wake routines as a key component of sleep education interventions.

The Impact of Daytime Napping Following Normal Night-Time Sleep on Physical Performance: A Systematic Review, Meta-analysis and Meta-regression.

BACKGROUND: Daytime napping is used by athletes as a strategy to supplement night time sleep and aid physical performance. However, no meta-analytical overview regarding the impact of napping following a night of normal sleep (7-9 h) on physical performance is available. OBJECTIVE: The aim of this study was to evaluate the effect of daytime napping following normal night-time sleep on physical performance in physically active individuals and athletes. METHODS: This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Seven electronic databases (i.e., PubMed, Web of Science, Scopus, SPORTDiscus, CINAHL, SCIELO, and EBSCOhost) were used to search for relevant studies that investigated the impact of daytime napping, following normal night-time sleep, on physical performance in physically active individuals and athletes, published in any language, and available before September 01, 2022. Studies that included assessments of any physical performance measures were included. QualSyst was used to assess the methodological quality of the studies. RESULTS: Of 18 selected articles, 15 were of strong quality and 3 were of moderate quality. Compared with no-nap conditions, physically active individuals and athletes who napped experienced an increase in highest distance (effect size [ES] 1.026; p < 0.001) and total distance (ES 0.737; p < 0.001), and a decrease in fatigue index (ES 0.839, p = 0.008) during the 5-m shuttle run test (5MSRT). However, napping yielded no effect on muscle force (ES 0.175; p = 0.267). No effect of napping was found in one study that measured sprint performance and in two studies that measured performance during the 30-s Wingate test. Two of three studies reported an increase in jump performance after napping. Two of three studies reported an increase in repeated sprints after napping. One study reported an increase in upper-body power performance after napping, and napping was beneficial for endurance performance in one of two studies. CONCLUSION: Following normal sleep, napping is beneficial for the performance of the 5MSRT, with no significant effect on muscle force. No firm conclusions can be drawn regarding other physical performance measures due to the limited number of studies.

A Strategy to Inform Athlete Sleep Support From Questionnaire Data and Its Application in an Elite Athlete Cohort.

PURPOSE: Information from the Pittsburgh Sleep Quality Index (PSQI) and Athlete Sleep Behavior Questionnaire (ASBQ) provide the ability to identify the sleep disturbances experienced by athletes and their associated athlete-specific challenges that cause these disturbances. However, determining the appropriate support strategy to optimize the sleep habits and characteristics of large groups of athletes can be time-consuming and resource-intensive. The purpose of this study was to characterize the sleep profiles of elite athletes to optimize sleep-support strategies and present a novel R package, AthSlpBehaviouR, to aid practitioners with athlete sleep monitoring and support efforts. METHODS: PSQI and ASBQ data were collected from a cohort of 412 elite athletes across 27 sports through an electronic survey. A k-means cluster analysis was employed to characterize the unique sleep-characteristic typologies based on PSQI and ASBQ component scores. RESULTS: Three unique clusters were identified and qualitatively labeled based on the z scores of the PSQI components and ASBQ components: cluster 1, "high-priority; poor overall sleep characteristics + behavioral-focused support"; cluster 2, "medium-priority, sleep disturbances + routine/environment-focused support"; and cluster 3, "low-priority; acceptable sleep characteristics + general support." CONCLUSIONS: The findings of this study highlight the practical utility of an unsupervised learning approach to perform clustering on questionnaire data to inform athlete sleep-support recommendations. Practitioners can consider using the AthSlpBehaviouR package to adopt a similar approach in athlete sleep screening and support provision.

Investigating the sleep habits in individual and team-sport athletes using the Athlete Sleep Behavior Questionnaire and the Pittsburgh Sleep Quality Index.

Objectives: There is limited large-scale data on maladaptive sleep practices in elite adult athletes and their influence on sleep characteristics. This study aimed to identify differences in sleep behaviours between individual and team-sport athletes using two sleep questionnaires. Material and Methods: 407 (237 male, 170 female) elite adult athletes across sixteen sports (9 individual-sports, 7 team-sports) completed the Athlete Sleep Behavior Questionnaire (ASBQ) and the Pittsburgh Sleep Quality Index (PSQI). Results: Individual-sport athletes reported greater total sleep time and higher sleep efficiency than team-sport athletes (p<0.05, d=0.28-0.29). There were no differences between global scores for the PSQI, however, there was a difference between global scores for the ASBQ as well as multiple individual items from both questionnaires (p<0.05), indicating poorer behaviours in team-sport athletes. Discussion: Team-sport athletes displayed more maladaptive pre-sleep behaviours and poorer sleep characteristics than individual-sport athletes.

Predicting Youth Athlete Sleep Quality and the Development of a Translational Tool to Inform Practitioner Decision Making.

BACKGROUND: Identifying key variables that predict sleep quality in youth athletes allows practitioners to monitor the most parsimonious set of variables that can improve athlete buy-in and compliance for athlete self-report measurement. Translating these findings into a decision-making tool could facilitate practitioner willingness to monitor sleep in athletes. HYPOTHESIS: Key predictor variables, identified by feature reduction techniques, will lead to higher predictive accuracy in determining youth athletes with poor sleep quality. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: A group (N = 115) of elite youth athletes completed questionnaires consisting of the Pittsburgh Sleep Quality Index and questions on sport participation, training, sleep environment, and sleep hygiene habits. A least absolute shrinkage and selection operator regression model was used for feature reduction and to select factors to train a feature-reduced sleep quality classification model. These were compared with a classification model utilizing the full feature set. RESULTS: Sport type, training before 8 am, training hours per week, presleep computer usage, presleep texting or calling, prebedtime reading, and during-sleep time checks on digital devices were identified as variables of greatest influence on sleep quality and used for the reduced feature set modeling. The reduced feature set model performed better (area under the curve, 0.80; sensitivity, 0.57; specificity, 0.80) than the full feature set models in classifying youth athlete sleep quality. CONCLUSION: The findings of our study highlight that sleep quality of elite youth athletes is best predicted by specific sport participation, training, and sleep hygiene habits. CLINICAL RELEVANCE: Education and interventions around the training and sleep hygiene factors that were identified to most influence the sleep quality of youth athletes could be prioritized to optimize their sleep characteristics. The developed sleep quality nomogram may be useful as a decision-making tool to improve sleep monitoring practice among practitioners.

Questionnaire-Derived Sleep Habits and Academic Achievement in First Year University Students.

This study aimed to determine the effect of sleep quantity and quality via the Pittsburgh Sleep Quality Index (PSQI) on students' academic achievement in their first year of university study. In this cross-sectional study, 193 students (102 female, 91 male, mean ± SD; age = 19.3 ± 2.9 y) from an undergraduate Health degree in New Zealand completed the PSQI four weeks prior to the end of the semester in their first year of university study. Results from three core subjects in the first semester were averaged and correlations between the PSQI and academic success were evaluated using Spearman's rho (ρ). The group were also trichotomized using a PSQI global score of ≤5 as the threshold for "good" sleepers (n = 62, 32%), a score of 5-8 for "moderate" sleepers (n = 63, 33%) and a score ≥8 to characterize "poor" sleepers (n = 68, 35%). Overall, students averaged 7 h 37 min of self-reported sleep duration with an average bedtime of 22:55 p.m. and wake time of 8:01 a.m. There was a significant, small inverse relationship between academic performance and bedtime (p = 0.03, ρ = -0.14), with those going to bed earlier having superior academic success. The trichotomized data demonstrated no significant differences in academic performance between students with poor, moderate and good sleep quality (p = 0.92). Later bedtimes were associated with lower academic performance in a group of first year university students. However, there were no other relationships observed between academic success and self-reported sleep quality or quantity as determined by the PSQI. Enhancing awareness of the impact of sleep timing on academic success should be prioritized and strategies to improve sleep hygiene should be promoted to university students.

Dimensionality Reduction for Countermovement Jump Metrics.

PURPOSE: Dozens of variables can be derived from the countermovement jump (CMJ). However, this does not guarantee an increase in useful information because many of the variables are highly correlated. Furthermore, practitioners should seek to find the simplest solution to performance testing and reporting challenges. The purpose of this investigation was to show how to apply dimensionality reduction to CMJ data with a view to offer practitioners solutions to aid applications in high-performance settings. METHODS: The data were collected from 3 cohorts using 3 different devices. Dimensionality reduction was undertaken on the extracted variables by way of principal component analysis and maximum likelihood factor analysis. RESULTS: Over 90% of the variance in each CMJ data set could be explained in 3 or 4 principal components. Similarly, 2 to 3 factors could successfully explain the CMJ. CONCLUSIONS: The application of dimensional reduction through principal component analysis and factor analysis allowed for the identification of key variables that strongly contributed to distinct aspects of jump performance. Practitioners and scientists can consider the information derived from these procedures in several ways to streamline the transfer of CMJ test information.

Sleep Characteristics of Elite Youth Athletes: A Clustering Approach to Optimize Sleep Support Strategies.

PURPOSE: Elite athletes experience chronic sleep insufficiency due to training and competition schedules. However, there is little research on sleep and caffeine use of elite youth athletes and a need for a more nuanced understanding of their sleep difficulties. This study aimed to (1) examine the differences in sleep characteristics of elite youth athletes by individual and team sports, (2) study the associations between behavioral risk factors associated with obstructive sleep apnea and caffeine use with sleep quality, and (3) characterize the latent sleep profiles of elite youth athletes to optimize the sleep support strategy. METHODS: A group (N = 135) of elite national youth athletes completed a self-administered questionnaire consisting of the Pittsburgh Sleep Quality Index (PSQI) and questions pertaining to obstructive sleep apnea, napping behavior, and caffeine use. K-means clustering was used to characterize unique sleep characteristic subgroups based on PSQI components. RESULTS: Athletes reported 7.0 (SD = 1.2) hours of sleep. Out of the total group, 45.2% of the athletes had poor quality sleep (PSQI global >5), with team-sport athletes reporting significantly poorer sleep quality than individual-sport athletes. Multiple logistic regression analysis indicated that sport type significantly correlated with poor sleep quality. The K-means clustering algorithm classified athletes' underlying sleep characteristics into 4 clusters to efficiently identify athletes with similar underlying sleep issues to enhance interventional strategies. CONCLUSION: These findings suggest that elite youth team-sport athletes are more susceptible to poorer sleep quality than individual-sport athletes. Clustering methods can help practitioners characterize sleep-related problems and develop efficient athlete support strategies.

Relationships between Physical Activity, Work Ability, Absenteeism and Presenteeism in Australian and New Zealand Adults during COVID-19.

Public health movement and social restrictions imposed by the Australian and New Zealand governments in response to the COVID-19 pandemic influenced the working environment and may have affected health behaviours, work ability, and job performance. The aim of this study was to determine the associations between health behaviours and work ability and performance during COVID-19 restrictions and if health behaviours were related to demographic or population factors. A cross-sectional survey was used to gather responses from 433 adult employees in Australia and New Zealand between June and August 2020. The survey requested demographic information and used the International Physical Activity Questionnaire, Work Ability Index, and the World Health Organisation's Health and Work Performance Questionnaire. Multivariate regression models were used to explore relationships between the identified variables while controlling for several possible confounders. Being sufficiently physically active was associated with higher reported physical (aOR = 2.1; p = 0.001) and mental work abilities (aOR = 1.8; p = 0.007) and self-reported job performance (i.e., lower presenteeism) (median +7.42%; p = 0.03). Part-time employees were 56% less likely (p = 0.002) to report a good or very good mental work ability. Those with existing medical conditions were 14% less likely (p = 0.008) to be sufficiently active and 80% less likely (p = 0.002) to report rather good or very good physical work ability. Being sufficiently active was associated with higher physical and mental work abilities and better job performance during the COVID-19 pandemic. Employers should support opportunities for regular physical activity and provide specific support to individuals with medical conditions or in part-time employment.

Palatable Flavoured Fluids without Carbohydrates and Electrolytes Do Not Enhance Voluntary Fluid Consumption in Male Collegiate Basketball Players in the Heat.

Using palatable fluids to enhance drinking in athletes who display insufficient compensatory hydration behaviour may mitigate the risks of hypohydration and performance deficits. However, it is unclear whether flavour can independently enhance fluid consumption. This study examined the effects of a colourless, artificially sweetened flavoured water (FW), without carbohydrates and with negligible amounts of sodium, compared to plain water (W) on fluid consumption in male collegiate basketball players in a practical game setting. Eighteen male basketball players (age 23.1 ± 1.3 years) played a 3v3 basketball small-sided game. The players were randomly assigned to consume either FW or W. Pre-game urine-specific gravity, fluid consumption, body mass, and hedonic taste perceptions were assessed. Basketball performance was analysed through notational analysis. Ratings of perceived exertion and thirst were recorded at pre-, post-game, and at each rest period. Heart rate was recorded throughout the gameplay. Despite significantly higher hedonic ratings for FW than W (6.78 ± 0.83 vs. 5.56 ± 1.33, p = 0.033, d = 1.36), there were no significant differences in fluid consumption (1083 ± 32 mL vs. 1421 ± 403 mL, p = 0.068, d = 0.92). Our result highlighted that using palatable fluids as a strategy to increase fluid consumption during high-intensity gameplay in the heat may not be effective if used without carbohydrates and electrolytes. Practitioners could consider both fluid palatability and composition in establishing a hydration plan for athletes.

Hydration Status and Fluid Replacement Strategies of High-Performance Adolescent Athletes: An Application of Machine Learning to Distinguish Hydration Characteristics.

There are limited data on the fluid balance characteristics and fluid replenishment behaviors of high-performance adolescent athletes. The heterogeneity of hydration status and practices of adolescent athletes warrant efficient approaches to individualizing hydration strategies. This study aimed to evaluate and characterize the hydration status and fluid balance characteristics of high-performance adolescent athletes and examine the differences in fluid consumption behaviors during training. In total, 105 high-performance adolescent athletes (male: 66, female: 39; age 14.1 ± 1.0 y) across 11 sports had their hydration status assessed on three separate occasions-upon rising and before a low and a high-intensity training session (pre-training). The results showed that 20-44% of athletes were identified as hypohydrated, with 21-44% and 15-34% of athletes commencing low- and high-intensity training in a hypohydrated state, respectively. Linear mixed model (LMM) analyses revealed that athletes who were hypohydrated consumed more fluid (F (1.183.85)) = 5.91, (p = 0.016). Additional K-means cluster analyses performed highlighted three clusters: "Heavy sweaters with sufficient compensatory hydration habits," "Heavy sweaters with insufficient compensatory hydration habits" and "Light sweaters with sufficient compensatory hydration habits". Our results highlight that high-performance adolescent athletes with ad libitum drinking have compensatory mechanisms to replenish fluids lost from training. The approach to distinguish athletes by hydration characteristics could assist practitioners in prioritizing future hydration intervention protocols.

Effects of a Short Daytime Nap on Shooting and Sprint Performance in High-Level Adolescent Athletes.

PURPOSE: To investigate the sport-specific performance effect of a brief afternoon nap on high-level Asian adolescent student-athletes who were habitually short sleepers. METHODS: Participants were randomly assigned to a nap or nonnap (reading) condition. In the first study, 12 male shooters (13.8 [1.0] y) performed a shooting assessment (20 competition shots) with heart-rate variability monitored during the assessment. In the second study, 19 male track-and-field athletes (14.8 [1.1] y) performed a 20-m sprint-performance assessment. Subjective measures of sleepiness and alertness were obtained in both studies. RESULTS: The brief nap had no effect on any measure of shooting performance (P > .05) or autonomic function (P > .05) in shooters. However, the fastest 20-m sprint times increased significantly (P < .05) from 3.385 (0.128) s to 3.411 (0.143) s, with mean 2-m times trending toward significance (P < .1) among the track-and-field athletes. No significant differences were observed in any other measures. CONCLUSIONS: The results of the research indicate varying effects of naps between sport-specific performance measures. Napping had no effect on shooting performance, whereas a negative effect existed in 20-m sprint performance, potentially due to sleep inertia. Considering these findings, some caution is warranted when advocating naps for adolescent athletes.