The Utility of Melatonin for the Treatment of Sleep Disturbance After Traumatic Brain Injury: A Scoping Review.

OBJECTIVE: To investigate the utility of melatonin supplementation as a treatment option for individuals with sleep disturbance after traumatic brain injury (TBI). DATA SOURCES: A systematic search was conducted in 6 electronic databases (Medline, AMED, CINAHL, Embase, Scopus, and SPORTDiscus) from earliest records to April 2022. STUDY SELECTION: Studies were eligible for inclusion if they met the following criteria: a) human participants with sleep disturbance after TBI, b) melatonin or melatonergic agent used as an intervention to treat sleep disturbance, and c) outcomes of melatonin administration reported. All TBI severity types (mild, moderate, and severe) were eligible. The initial search retrieved a total of 595 articles, with 9 studies meeting the eligibility criteria. DATA EXTRACTION: Two reviewers independently extracted data from eligible studies and assessed methodological quality. Extracted data consisted of participant and injury characteristics, melatonin interventional properties, and sleep outcome. Methodological quality was assessed via the Downs and Black checklist. DATA SYNTHESIS: A total of 251 participants with TBI-induced sleep disturbance (mean age range: 14.0-42.5 years) were included. Melatonin, Circadin (prolonged-release melatonin), or Ramelteon (melatonin receptor agonist) were administered. Dosages and intervention duration ranged from 2 to 10 mg and 3 to 12 weeks, respectively. Eight out of 9 studies reported positive outcomes after melatonin treatment. Significant improvements in subjective sleep quality, objective sleep efficiency, and total sleep time were found with melatonin. Reductions in self-reported fatigue, anxiety, and depressive symptoms were also observed with melatonin treatment. No serious adverse events were reported after melatonin administration. CONCLUSION: Melatonin has good tolerability after short-term use and the potential to be a therapeutic agent for those with sleep disturbance after TBI. Melatonin was shown to be beneficial to sleep quality, sleep duration, and sleep efficiency. Additional clinically relevant outcomes of improved mental health suggest that melatonin use may be a promising treatment option for individuals experiencing co-occurring disorders of mood and sleep disturbance post-injury.

Association of Sleep Disturbance With Neurocognition, Symptom Severity, and Recovery in Pediatric Concussion: A 10-Year Retrospective Analysis of a Tertiary Referral Concussion Clinic.

OBJECTIVES: To investigate the relationship between sleep disturbance, neurocognition, symptom severity, and recovery in children and adolescents with concussion. Sex-related comparisons were also examined. SETTING: Pediatric tertiary referral concussion clinic. PARTICIPANTS: Children and adolescents (aged 6-18 years; n = 554) diagnosed with concussion. DESIGN: Cross-sectional retrospective study. MAIN MEASURES: Assessment data were obtained from Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) Applications. Sleep disturbance was quantified using the sleep-related domains of the Post-Concussion Symptom Scale (PCSS) and self-report sleep duration. Sleep duration was categorized as short (<7 hours), intermediate (7-9 hours), and long (≥9 hours). Outcome measures included neurocognition, measured via composite scores of ImPACT cognitive domains (verbal memory, visual memory, visual motor speed, reaction time); symptom severity, using the PCSS; and concussion recovery time (days). RESULTS: Short sleep resulted in significantly poorer verbal memory ( P = .03), visual memory ( P = .02), and reaction time ( P = .01). Sleep disturbance was strongly associated with total symptom burden (ρ = 0.90, P < .001). Recovery time, median (interquartile range), was significantly prolonged with short sleep, 61 (30-136) days, compared with intermediate, 38 (21-72) days, and long, 34 (19-71) days, sleep ( P < .001). Overall, female participants demonstrated significantly longer recovery times than male participants (mean 91 ± 95 vs 58 ± 85 days, P < .001). Females exhibited similar concussion recovery times irrespective of reported sleep duration ( P = .95), whereas mean recovery time in males was significantly longer with short sleep (84 ± 82 days) than with intermediate (61 ± 106 days) and long (49 ± 62 days) sleep ( P < .001). CONCLUSION: Sleep disturbance following concussion poses as a promising modifiable risk factor to alleviate postinjury impairments, including cognitive deficits and symptom burden. Female children were found to experience more severe concussion symptoms and protracted recovery times than their male counterparts. Investigations into the factors that may contribute to sex-related differences following concussion are warranted.

Effects of Age and Sex on Aerobic Fitness, Sprint Performance, and Change of Direction Speed in High School Athletes.

ABSTRACT: Hackett, DA, He, W, Fleeton, JRM, Orr, R, and Sanders, RH. Effects of age and sex on aerobic fitness, sprint performance, and change of direction speed in high school athletes. J Strength Cond Res 37(5): 325-331, 2023-The purpose of this study was to examine the effects of sex and age on aerobic fitness, sprinting performance, and change of direction speed (CODS) in high school athletes, with consideration for maturity. This cross-sectional study involved 2,132 adolescents (1,415 male and 717 female athletes) aged 12.0-15.9 years. Assessment of aerobic fitness using the 20-m multistage fitness test (20MSFT) and 20-m sprint and CODS using the 505 test was performed. For the analysis of data, subjects were separated into 4 age groups: U/13 years, U/14 years, U/15 years, and U/16 years. Estimated age at peak height velocity was a covariate in the data analysis to control for maturity status. Compared with female athletes, male athletes had superior performances at all age groups in 10-m sprint ( p < 0.001, effect size [ES] = >-0.44), 20-m sprint ( p < 0.001, ES = >-0.55), and 505 test ( p < 0.001, ES = >-0.41). Female athletes performed better than male athletes in 20MSFT at U/13 ( p < 0.01, ES = -0.22); however, male athletes had better performances at U/15 ( p < 0.01, ES = 0.27) and U/16 ( p < 0.001, ES = 0.67). At each consecutive age group, male athletes improve their performances in 20MSFT and sprints and at U/14 and U/16 in the 505 test ( p < 0.001, ES > -0.37). Female athletes showed no improvement in the 20MSFT and 505 test between U/13-U/16 but showed improved sprint performance at U/15 compared with U/13 and at U/16 compared with U/14 ( p < 0.05). This study shows that adolescent male athletes perform consistently better than female athletes in running-related field-based tests and display continuous improvements across age groups.

Greater symptom burden results in reduced exercise tolerance in adolescents following concussion.

OBJECTIVES: To explore the relationship between symptoms and exercise tolerance in adolescents following concussion. METHODS: A retrospective analysis of 417 adolescents who attended a concussion service between January 2015 and April 2021 was performed, with 149 meeting eligibility criteria for inclusion. Post-Concussion Symptom Scale (PCSS) and graded exercise tolerance time (min) were assessed at initial and follow-up visits. Spearman's correlation was used to examine the relationship between PCSS scores and exercise time. RESULTS: Adolescents (n = 149, 13.9 ± 1.7 years, 66.4% male) presented at 28.6 ± 19.7 days post-injury. Statistically significant correlations were identified between initial (r = -0.36, p < .001) and follow-up (r = -0.41, p < .001) PCSS scores and exercise time among all participants. Initial PCSS and initial exercise time were inversely correlated for males (r = -0.24, p = .018) and females (r = -0.22, p = .127). Follow-up PCSS and follow-up exercise time were inversely correlated for males (r = -0.30, p = .003) and females (r = -0.35, p = .014). CONCLUSION: There is a statistically significant relationship between higher PCSS and poorer exercise time and both factors should be considered together to provide the most accurate assessment, particularly in females.

Effect of Set-Structure on Upper-Body Muscular Hypertrophy and Performance in Recreationally-Trained Male and Female.

ABSTRACT: Davies, TB, Halaki, M, Orr, R, Mitchell, L, Helms, ER, Clarke, J, and Hackett, DA. Effect of set structure on upper-body muscular hypertrophy and performance in recreationally trained men and women. J Strength Cond Res 36(8): 2176-2185, 2022-This study explored the effect of volume-equated traditional-set and cluster-set structures on muscular hypertrophy and performance after high-load resistance training manipulating the bench press exercise. Twenty-one recreationally trained subjects (12 men and 9 women) performed a 3-week familiarization phase and were then randomized into one of two 8-week upper-body and lower-body split programs occurring over 3 and then progressing to 4 sessions per week. Subjects performed 4 sets of 5 repetitions at 85% one repetition maximum (1RM) using a traditional-set structure (TRAD, n = 10), which involved 5 minutes of interset rest only, or a cluster-set structure, which included 30-second inter-repetition rest and 3 minutes of interset rest (CLUS, n = 11). A 1RM bench press, repetitions to failure at 70% 1RM, regional muscle thickness, and dual-energy x-ray absorptiometry were used to estimate changes in muscular strength, local muscular endurance, regional muscular hypertrophy, and body composition, respectively. Velocity loss was assessed using a linear position transducer at the intervention midpoint. TRAD demonstrated a significantly greater velocity loss magnitude (g = 1.50) and muscle thickness of the proximal pectoralis major (g = -0.34) compared with CLUS. There were no significant differences between groups for the remaining outcomes, although a small effect size favoring TRAD was observed for the middle region of the pectoralis major (g = -0.25). It seems that the greater velocity losses during sets observed in traditional-set compared with cluster-set structures may promote superior muscular hypertrophy within specific regions of the pectoralis major in recreationally trained subjects.

Graded Exercise Testing Predicts Recovery Trajectory of Concussion in Children and Adolescents.

OBJECTIVE: To determine whether graded exercise testing can predict recovery trajectory of concussion in children and adolescents. DESIGN: Prospective study. SETTING: Children's Hospital, Westmead, Australia. PARTICIPANTS: One hundred thirty-nine children aged 12 to 16 years at 5 to 7 days after an acute concussive injury. INTERVENTION: Graded exercise testing on a treadmill at the subacute phase to assess symptom provocation and determine clinical recovery indicating readiness to commence a return to activity (RTA) protocol. Exercise time to symptom exacerbation and clinical recovery were measured. MAIN OUTCOME MEASURES: Standard concussion assessment and clinical testing (neurocognitive, vestibular/ocular, and balance) were conducted to determine major clinical drivers/indicators. RESULTS: Participants (mean age 12.4 ± 2.8 years, 73% male) had a confirmed sport-related concussion. The main clinical drivers identified on exercise testing were headache, balance, and vestibular dysfunction. Participants fell into 1 of 2 groups, exercise-tolerant (54%) and exercise-intolerant (46%). Exercise-tolerant patients showed mild clinical indicators, no symptom exacerbation during 10.3 ± 3.3 minutes of exercise, were safely transitioned to a RTA protocol, and recovered within 10 days. Exercise-intolerant patients had high clinical indicators, significant symptom exacerbation at 4.2 ± 1.6 minutes of exercise, and prolonged recovery of 45.6 days. No adverse effects from exercise were reported in either group. Combined use of provocative exercise and clinical testing was 93% predictive of outcome. CONCLUSIONS: Exercise testing during the subacute phase after a concussion can predict longer recovery. Exercise testing can identify a unique window where patients can be safely transitioned to activity, enabling clinicians to better inform patients and families, allocate resources and streamline care.

Effects of age and sex on field-based measures of muscle strength and power of the upper and lower body in adolescents.

Field-based tests including the medicine ball chest throw (MBCT) and vertical jump are used to assess muscle performance. To date no study has compared performances of these field-based tests in adolescents across a range of ages. The aim of this study was to examine the effects of age and sex on MBCT and countermovement jump (CMJ) performance in adolescents.This cross-sectional study involved 2192 adolescents (1477 males and 715 females) aged between 12 and 17 years. Trials of the MBCT and CMJ were performed with CMJ peak power estimated. Males had significantly greater MBCT distance, CMJ height and CMJ peak power at each consecutive age group separated by 1 year (p < 0.001). Females generally showed significantly greater performances across a larger age range of at least 2 years for MBCT (p ≤ 0.004) and CMJ peak power (p ≤ 0.018). Males had greater performances than females for MBCT distance, CMJ height, and CMJ peak power from 13 years and above (p < 0.001). Sex differences widened with increasing age for all tests from ~5-8% at 12 years progressing to 24-29% at 16-17 years. This study shows the effects of age and sex is similar for both the MBCT and CMJ tests in adolescents.

Effect of Set-Structure on Upper-Body Muscular Hypertrophy and Performance in Recreationally-Trained Male and Female.

ABSTRACT: Davies, TB, Halaki, M, Orr, R, Mitchell, L, Helms, ER, Clarke, J, and Hackett, DA. Effect of set structure on upper-body muscular hypertrophy and performance in recreationally trained men and women. J Strength Cond Res XX(X): 000-000, 2021-This study explored the effect of volume-equated traditional-set and cluster-set structures on muscular hypertrophy and performance after high-load resistance training manipulating the bench press exercise. Twenty-one recreationally trained subjects (12 men and 9 women) performed a 3-week familiarization phase and were then randomized into one of two 8-week upper-body and lower-body split programs occurring over 3 and then progressing to 4 sessions per week. Subjects performed 4 sets of 5 repetitions at 85% one repetition maximum (1RM) using a traditional-set structure (TRAD, n = 10), which involved 5 minutes of interset rest only, or a cluster-set structure, which included 30-second inter-repetition rest and 3 minutes of interset rest (CLUS, n = 11). A 1RM bench press, repetitions to failure at 70% 1RM, regional muscle thickness, and dual-energy x-ray absorptiometry were used to estimate changes in muscular strength, local muscular endurance, regional muscular hypertrophy, and body composition, respectively. Velocity loss was assessed using a linear position transducer at the intervention midpoint. TRAD demonstrated a significantly greater velocity loss magnitude (g = 1.50) and muscle thickness of the proximal pectoralis major (g = -0.34) compared with CLUS. There were no significant differences between groups for the remaining outcomes, although a small effect size favoring TRAD was observed for the middle region of the pectoralis major (g = -0.25). It seems that the greater velocity losses during sets observed in traditional-set compared with cluster-set structures may promote superior muscular hypertrophy within specific regions of the pectoralis major in recreationally trained subjects.

Association of Simple Step Test With Readiness for Exercise in Youth After Concussion.

OBJECTIVES: We hypothesized that a submaximal step test would be associated with readiness to commence graded exercise in children and adolescents with concussion. METHODS: Children and adolescents aged 8 to 18 years performed standard concussion clinical assessment for vestibular/ocular and balance impairment, and exercise examination utilizing the 3-minute Kasch Pulse Recovery test (KPR) and a symptom-limited graded exercise test (GXT). Outcome measures included activity readiness and symptom exacerbation. RESULTS: Forty-five participants (mean age 13.2 ± 2.1 years, 76% male) had a confirmed concussion (73% sports-related). Some participants required follow-up testing giving 75 clinical presentations. Sensitivity and specificity of the KPR were 100% and 95.7%, respectively. Area under the receiver operating characteristics curve was 0.979. Activity readiness to GXT and KPR was strongly associated (χ = 21.672, P < .001), while symptom exacerbation showed a significant correlation between testing methods (r = 0.796, P < .001). Better exercise performance on GXT and KPR was significantly correlated with normal Vestibular/Ocular Motor Screening (rs = -0.380, P = .010, and rs = -0.281, P = .017, respectively) and Modified Balance Error Scoring System (rs = -0.452, P < .001, and rs = -0.301, P = .010, respectively). CONCLUSION: The KPR is a simple and practical tool to determine whether it is appropriate for a child or adolescent with concussion to commence graded exercise.

Changes in Bench Press Velocity and Power After 8 Weeks of High-Load Cluster- or Traditional-Set Structures.

Davies, TB, Halaki, M, Orr, R, Helms, ER, and Hackett, DA. Changes in bench press velocity and power after 8 weeks of high-load cluster- or traditional-set structures. J Strength Cond Res 34(10): 2734-2742, 2020-This study investigated the effects of high-load cluster- vs. traditional-set structures using the bench press on velocity and power. Twenty-one resistance-trained individuals (male = 12, female = 9) performed a 3-week familiarization block followed by randomization into 1 of 2 upper- and lower-body split training routines performed for 8 weeks. The bench press was the only exercise manipulated with subjects using either cluster-set (CLUS, n = 11) or traditional-set (TRAD, n = 10) structures during training sessions. Subjects performed 4 sets of 5 repetitions at 85% 1 repetition maximum (1RM) with CLUS having a 30-second inter-repetition, and 3-minute interset rest while TRAD had a 5-minute interset rest. A load-velocity profile of relative loads derived from a 1RM test was used to assess velocity and power (absolute and relative to body mass) on the bench press. Significant improvements over time were found across various loads ranging from 45 to 75% 1RM for absolute and relative peak power (p = 0.006-0.041), and mean power (p = 0.001-0.032). Significant decreases over time were found at 55% 1RM and 65% 1RM for peak velocity (p = 0.027 and p = 0.012, respectively) and mean velocity (p = 0.047 and p = 0.022, respectively). There were no significant group or group by time interactions found for all outcomes. Within the context of high-load resistance training, set structure seems to be of less importance for changes in bench press velocity and power provided there is an intention to lift with maximal concentric velocity.

Movement Demands of Rugby Sevens in Men and Women: A Systematic Review and Meta-Analysis.

Ball, S, Halaki, M, and Orr, R. Movement demands of rugby sevens in men and women: A systematic review and meta-analysis. J Strength Cond Res 33(12): 3475-3490, 2019-Global positioning systems (GPS) provide comprehensive information of player movement demands in rugby 7's. Although studies have investigated the use of GPS within many field-based team sports, the application of GPS within rugby 7's remains unclear. The aim of this review was to evaluate the movement demands and conduct a meta-analysis on comparable GPS measures to assess player movement in rugby 7's. A systematic search of electronic databases Medline, SPORTDiscus, Cinahl, Web of Science, Scopus, and Embase was performed. The search strategy combined terms covering: global positioning systems AND rugby union. Studies were included if they contained rugby sevens' players monitored by GPS. Meta-analyses were conducted to provide a pooled mean and confidence intervals (CIs) on outcomes for data extracted from at least 3 studies. A total of 24 publications were eligible for review and included 661 (447 male and 214 female) rugby 7's players. Meta-analysis indicated that male players cover greater relative distance (male: 108.5 m·min, 95% CI [104.9-112.1] m·min, female: 100.3 m·min, 95% CI [96.0-104.7] m·min), distance at >12.6 km·h (male: 449.3 m, 95% CI [427.0-471.5] m, female: 339.5 m, 95% CI [291.1-387.9] m) and >18.0 km·h (male: 190.3 m, 95% CI [180.7-199.9] m, female: 129.9 m, 95% CI [99.9-159.8] m), and have a greater maximum velocity compared with female players (male: 29.8 km·h, 95% CI [29.2-30.4] km·h, female: 24.6 km·h, 95% CI [23.3-25.9] km·h), whereas relative distance is higher for the first half (109.5 m·min, 95% CI [99.1-120.0] m·min) compared with the second half (93.8 m·min, 95% CI [87.4-100.1] m·min) of match play across sexes and playing levels. Independent velocity zone classifications should apply for male and female players, whereas velocity thresholds should remain consistent across studies. Rugby 7's training intensity should vary between male and female players.

Energetic Demands of Interchange and Full-Match Rugby League Players.

Cummins, CJ, Gray, AJ, Shorter, KA, Halaki, M, and Orr, R. Energetic demands of interchange and full-match rugby league players. J Strength Cond Res 32(12): 3456-3464, 2018-The purpose of this study was to describe and compare the metabolic demands of rugby league for interchange and full-match players in relation to positional groups. Eighteen elite rugby league players were recruited. A time-motion model was used to estimate the energy expenditure and metabolic demands of rugby league match-play using Global Positioning System (GPS) technology. This approach uses players' GPS velocity-time curves to examine running velocity. Players were categorized into positional groups (outside backs, adjustables, wide-running, and hit-up forwards) and then further categorized into full-match or interchange players. Compared with their full-match counterparts, interchange wide-running forwards expended greater energy (43.1 ± 6.1 vs. 28.6 ± 7.5 kJ·kg, p ≤ 0.001, effect size [ES] = -2.38) and produced a higher anaerobic index (p = 0.016, ES = 0.56) and mean power (7.4%, p = 0.003, ES = 0.66) per match. Full-match adjustables expended 94.8% more energy (p ≤ 0.001, ES = -2.3) and performed more moderate accelerations (10.1%, p = 0.014, ES = -0.57) and decelerations (7.6%, p = 0.017, ES = -0.8), than their interchange counterparts. Outside backs did not interchange and hit-up forwards rarely (n = 2) played an entire match. Differing metabolic demands were identified for interchange and full-match players across positional groups, suggesting position-specific conditioning drills are required to model the energetic demands of match-play.

Training volume and soft tissue injury in professional and non-professional rugby union players: a systematic review.

AIM: To investigate the relationship between training volume and soft tissue injury incidence, and characterise soft tissue injury in rugby union players. DESIGN: A systematic search of electronic databases was performed. The search strategy combined terms covering: training volume and injury, and rugby union, and players of all levels. DATA SOURCES: Medline, SPORTDiscus, Web of Science, Embase, PubMed. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies were included if they reported: male rugby union players, a clear definition of a rugby union injury, the amount of training volume undertaken by participants, and epidemiological data for soft-tissue injuries including the number or incidence. RESULTS: 15 studies were eligible for inclusion. Overall match and training injury incidence ranged from 3.3 to 218.0 injuries/1000 player match hours and 0.1-6.1 injuries/1000 player training hours, respectively. Muscle and tendon as well as joint (non-bone) and ligament injuries were the most frequently occurring injuries. The lower limb was the most prevalent injury location. Injury incidence was higher in professional rugby union players than non-professional players. Contact events were responsible for the greatest injury incidence. For non-contact mechanisms, running was responsible for the highest injury incidence. Inconsistent injury definitions hindered reliable comparison of injury data. The lack of reporting training volumes in hours per player per week limited the ability to investigate associations between training volume and injury incidence. CONCLUSIONS: A higher level of play may result in higher match injury incidence. Muscle and tendon injuries were the most common type of soft tissue injury, while the lower limb was the most common location of injury in rugby union players, and running was responsible for the highest injury incidence during non-contact events.

Time-Loss Injuries in Sub-Elite and Emerging Rugby League Players.

This study aimed to 1) investigate the incidence and characteristics of injuries in emerging rugby league players; and 2) explore the differences in injury incidence and characteristics between the various sub-elite competitions. An NRL emerging player development squad (n = 34) was observed from the beginning of pre-season until the finish of competition. Time-loss injury was defined as any physical pain or impairment sustained that resulted in players missing a match. Injuries were categorised according to circumstance, incidence, characteristics, playing position and competition level. Of a total of 196 injuries that were recorded, 45 were time-loss and 151 were transient. The total injury incidence was 7.9/1,000 playing hours. The most common sites for time-loss injuries were the shoulder, ankle/foot and knee. Ligament injuries accounted for the highest number of injuries by type. Forwards sustained the greatest number of injuries. However, backs suffered the greatest injury cost. The majority of time-loss injuries were sustained during competition matches. Injuries sustained during open age matches resulted in significantly higher injury cost to those received at NYC matches. NRL development and emerging rugby league players are exposed to high risk of injury. Lower limb and shoulder injuries to bone or connective tissue are prevalent as a result of contact during match play. Players at this developmental level feed into several different playing squads where disparities in physical development, maturation, playing intensity and training regimes are evident. This presents a challenge in matching physiological capabilities with playing demands for NRL development squads.

Combined caffeine and carbohydrate ingestion: effects on nocturnal sleep and exercise performance in athletes.

PURPOSE: In athletes, caffeine use is common although its effects on sleep have not been widely studied. This randomised, double-blind, placebo-controlled crossover trial investigated the effects of late-afternoon caffeine and carbohydrate-electrolyte (CEB) co-ingestion on cycling performance and nocturnal sleep. METHODS: Six male cyclists/triathletes (age 27.5 ± 6.9 years) completed an afternoon training session (TS; cycling 80 min; 65% VO2max) followed by a 5 kJ kg(-1) cycling time trial (TT). Caffeine (split dose 2 × 3 mg kg(-1)) or placebo was administered 1 h prior and 40 min into the TS. A 7.4% CEB (3 ml kg(-1) every 15 min) was administered during the TS, followed 30 min after by a standardised evening meal. Participants retired at their usual bedtime and indices of sleep duration and quality were monitored via polysomnography. DATA: mean ± SD. RESULTS: All participants performed better in the caffeine TT (caffeine 19.7 ± 3.3; placebo 20.5 ± 3.5 min; p = 0.006), while ratings of perceived exertion (caffeine 12.0 ± 0.6; placebo 12.9 ± 0.7; p = 0.004) and heart rate (caffeine 175 ± 6; placebo 167 ± 11 bpm; p = 0.085) were lower in the caffeine TS. Caffeine intake induced significant disruptions to a number of sleep indices including increased sleep onset latency (caffeine 51.1 ± 34.7; placebo 10.2 ± 4.2 min; p = 0.028) and decreased sleep efficiency (caffeine 76.1 ± 19.6; placebo 91.5 ± 4.2%; p = 0.028), rapid eye movement sleep (caffeine 62.1 ± 19.6; placebo 85.8 ± 24.7 min; p = 0.028) and total sleep time (caffeine 391 ± 97; placebo 464 ± 49 min; p = 0.028). CONCLUSIONS: This study supports a performance-enhancing effect of caffeine, although athletes (especially those using caffeine for late-afternoon/evening training and competition) should consider its deleterious effects on sleep.

Children and exercise.

BACKGROUND: Exercise is widely understood to improve health outcomes in children and adolescents and to contribute to the prevention and management of many chronic conditions. Australian children are not currently meeting the recommended physical activity guidelines, and these habits are likely to extend into adulthood without intervention. OBJECTIVE: The aim of this paper is to provide general practitioners (GPs) with the tools to perform a basic exercise assessment with children and adolescents and an understanding of the core principles of exercise prescription for general and special paediatric populations. DISCUSSION: GPs are limited by time often precluding the assessment of exercise levels in children and adolescents unless it is immediately relevant to their presentation. This article discusses simple methods of assessing physical activity, the importance of appropriately prescribed exercise and its benefits for physical, psychological and social health and wellbeing.

Australian athletes' health behaviours and perceptions of role modelling and marketing of unhealthy products.

ISSUE ADDRESSED: This study examined Australian athletes' support for athletes' role in promoting physical activity and obesity prevention, the acceptability of unhealthy products promotion in sport, and their own health behaviours. METHODS: Surveys were conducted with (n = 1990) elite and sub-elite athletes recruited from 22 sports across Australia. Athletes' perceptions and behaviours were analysed across demographic and sport-related factors (e.g. individual vs team sport) and correlations calculated between perceptions and health behaviours. RESULTS: Most respondents supported a role for athletes in promoting physical activity and obesity prevention, and disagreed that athletes should promote unhealthy foods and alcohol (73.9%). Athletes reported low smoking rates, but high rates of binge drinking. Female, younger, individual and amateur athletes had more health-positive perceptions and healthier behaviours than older, male, team and professional athletes. More sympathy towards junk food and alcohol advertising in sport and less support for athletes as role models were associated with more unhealthy behaviours. CONCLUSIONS: Elite athletes are receptive to supporting health promotion through sport and many are not in agreement with the promotion of unhealthy products in sport or by sports people. Improving elite athletes' health behaviours would benefit not only the individual but also health promotion within elite sport.

Effect of high-volume cluster sets versus lower-volume traditional sets on muscular performance.

BACKGROUND: Similar muscle performance adaptations have been shown following volume-equated resistance training using cluster (CLUS) versus traditional (TRAD) set structures. This study aimed to examine the effects of higher-volume CLUS compared to lower-volume TRAD set structures on muscle performance. METHODS: Twenty resistance-trained males (age 20.9±4.3 years) were randomized into one of two bench press training routines performed for 6 weeks. Subjects in CLUS (N.=10), performed six sets of five repetitions at 85% one-repetition maximum (1RM) with 30 seconds inter-repetition rest and three minutes of inter-set rest. In contrast, subjects in TRAD (N.=10) performed three sets of five repetitions at 85% 1RM with five minutes of inter-set rest. Muscular strength (1RM), concentric velocity, power, local muscular endurance and maintenance of muscle performance (in training sessions) were assessed. RESULTS: For 1RM there was a significant time effect (P<0.001) with moderate effect sizes (ES) within each group (CLUS: ES=0.48; TRAD: ES=0.67). A trend towards significant time effect was found for concentric velocity (P=0.05; CLUS: ES=-0.36; TRAD ES=-0.96). There were no other significant time or group effects nor group × time interactions. Greater maintenance of concentric velocity and power (sets 1-3) was found for CLUS compared to TRAD at week one (P<0.05) but not at week 6. CONCLUSIONS: High load resistance training in the bench press exercise, utilizing intra-set rest periods to increase the training volume, does not yield any muscular performance benefits compared to traditional set structures.

Epidemiology of injuries in Australian junior rugby league players.

OBJECTIVES: Conduct a large-scale epidemiological study of injury characteristics (location, type, mechanism, severity, burden) and incidence in community junior rugby league. DESIGN: Prospective cohort epidemiology study. METHODS: Injury surveillance was conducted in three district leagues (Penrith, Canberra, Melbourne) in under 6 (U6) to under 18 years (U18) age groups across the 2016 season. Club sports trainers recorded all match/training medical-attention injuries using a commercial electronic application which recorded injury circumstances and characteristics. RESULTS: A total of 13,169 players from 897 teams participated and 408 (89% male) players sustained 485 injuries, 94% of which were match related. The overall injury incidence was 5.9 injuries/1000 player hours and highest in U13-U18 female players (22.2 injuries/1000 player hours). The mean injury severity of 16±31 days missed training/match-play caused an overall injury burden of 94.2 days missed/1000 player hours). Tackles accounted for 84% of injuries. Joint and contusion injuries were the most prevalent injury type and the head (35% total injuries, primarily bruising and bleeding) was the most injured body site. CONCLUSIONS: This is the first study to report injuries across a large cohort of all-age Australian community junior rugby league players over one season. Injury prevalence was lower than previously reported in junior rugby league suggesting the sport has not become more dangerous for junior players. These findings provide an evidence-base to inform or revise policy, training and injury prevention programs and athlete development pathways in relation to game-wide safety and develop best-practice protocols in injury management for rugby league athlete support personnel.