Changes in Intragastric Temperature Reflect Changes in Heat Stress Following Tepid Fluid Ingestion But Not Ice Slurry Ingestion

This study examined the effects of fluid and ice slurry ingestion on the relationship between intragastric temperature and rectal temperature in humans during physical activity. The purpose was to identify a technique to quantify changes in heat stress in situations when temperature probes are not feasible and when time constraints do not allow for a period long enough for an indigestible temperature capsule to reach the lower gastrointestinal tract. Eight moderately trained male runners inserted a rectal probe and ingested a telemetric capsule before randomized, crossover, pre-exercise ingestion of 7.5 mL x kg-1 x BM-1tepid fluid (22°C) or ice slurry (-1°C). Beverage ingestion was followed by a self-paced endurance running time trial. Average intragastric temperature was significantly lower than average rectal temperature across the run following both fluid (37.9 +/- 0.4°C vs. 38.4 +/- 0.2°C; p=0.003) and ice slurry ingestion (37.2 +/- 0.9 vs. 38.3 +/- 0.2; p=0.009). However, a strong relationship was observed between measurements following fluid (r=0.89) but not ice slurry (r=0.18). The average bias +/- limits of agreement during the run was 0.46 +/- 0.50 following fluid and 1.09 +/- 1.68 following ice slurry ingestion, which improved to 0.06 +/- 0.76 and 0.65 +/- 1.42, respectively when analyzed as delta scores. Intragastric temperature appears to not be a valid measure of absolute core body temperature at baseline or during exercise following either fluid or ice slurry ingestion. However, the relative changes in intragastric temperature during endurance exercise appears to be a strong indicator of systemic heat stress during exercise following ingestion of fluid at 22°C, but not ice slurry at -1°C

Development of the Basketball Exercise Simulation Test: A match-specific basketball fitness test

The aim of this study was to develop a reliable and valid field test that simulates the match-specific activity demands of male basketball competition. Fourteen male basketball players (mean ± SD, age: 24.9 ± 2.3 yr; stature: 187.8 ± 7.7 cm; body mass: 88.8 ± 10.5 kg) from state- (n = 6) and regional-level (n = 8) Australian competitions volunteered to participate. The Basketball Exercise Simulation Test (BEST) was developed using notational data describing the current activity demands of male basketball competition. Participants completed a repeat-sprint protocol, Yo-Yo Intermittent Recovery Test (Yo-Yo IRT) and 12-min BEST trial. Nine participants completed a further BEST trial at least 7 days later. Measures taken across the BEST included mean sprint and circuit time (s), sprint and circuit decrement (%) and total distance covered (m). Test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC), typical error of measurement, coefficient of variation (CV) and 95% confidence intervals (CI) across the two BEST trials. Criterion validity was calculated using Pearson Correlation analysis between each BEST measure and performance in the repeat-sprint protocol and Yo-Yo IRT. Mean sprint and circuit time and sprint and circuit decrement possessed high ICCs (0.92-0.99), while all measures except sprint (14.6%) and circuit decrement (16.8%) exhibited low CVs (<5%). Significant (p < 0.01) relationships were reported between mean sprint time, sprint decrement, mean circuit time and circuit decrement during the BEST and repeat-sprint performance (r = 0.80-0.92), as well as Yo-Yo IRT distance (r = -0.71-0.85). The present results suggest that the BEST is a reliable and valid match-specific test for the combined assessment of basketball-related anaerobic and aerobic fitness

THE EFFECT OF GRIP POSITION ON UPPER LIMB ANGULAR KINEMATICS DURING TENNIS TOPSPIN DOUBLE-HANDED BACKHAND STROKES

The purpose of this study was to compare the effect of grip on upper limb angular kinematics of sub-elite tennis players during a topspin double-handed backhand while aiming crosscourt. Sixteen sub-elite right-handed tennis players performed double-handed backhand trials using two different non-dominant grips (eastern & continental). Upper limb trajectory data was captured using the Vicon motion capture system (250 Hz). Greater peak angular velocity was observed in the eastern grip at the dominant shoulder (flexion, extension, abduction, adduction) and non-dominant shoulder (extension), elbow (pronation) and wrist (flexion, ulna and radial deviation). Subsequently peak linear velocities for the racket head (horizontal), and upper limb resultant joint centres were greater in the eastern condition. Collectively, these data suggest that using the eastern grip in the non-dominant limb is more optimal for developing racket head speed, and may provide coaches relevant information for athlete development in double-handed backhands

UPPER LIMB KINEMATICS DURING THE TOPSPIN DOUBLE-HANDED BACKHAND STROKE IN TENNIS

The purpose of this study was to compare non-dominant wrist kinematics during tennis double-handed backhand strokes in players using either an eastern or continental grip position. Trajectory data for two grips (eastern & continental) and depths (deep & short) were captured for sixteen sub-elite right-handed tennis players using a 12-camera Vicon motion capture system (250 Hz). The eastern grip demonstrated significantly faster horizontal racket head velocities compared to the continental grip. However, no differences were observed in accuracy or spin rate between grips (p \u3e 0.05). In the non-dominant upper limb for the continental condition, elbow flexion was smaller while wrist extension was larger throughout the swing. Collectively, these data suggest that the continental grip may place the wrist in a position that is more vulnerable to overuse injury

The Importance of Monitoring Sleep within Adolescent Athletes: Athletic, Academic, and Health Considerations

Opinion piece

Sleep Medication and Athletic Performance—The Evidence for Practitioners and Future Research Directions

Opinion piece

Peak match acceleration demands differentiate between elite youth and professional football players

Youth footballers need to be developed to meet the technical, tactical, and physical demands of professional level competition, ensuring that the transition between competition levels is successful. To quantify the physical demands, peak match intensities have been measured across football competition tiers, with team formations and tactical approaches shown to influence these physical demands. To date, no research has directly compared the physical demands of elite youth and professional footballers from a single club utilising common formations and tactical approaches. The current study quantified the total match and peak match running demands of youth and professional footballers from a single Australian A-League club. GPS data were collected across a single season from both a professional (n = 19; total observations = 199; mean ± SD; 26.7 ± 4.0 years) and elite youth (n = 21; total observations = 59; 17.9 ± 1.3 years) team. Total match demands and peak match running demands (1–10 min) were quantified for measures of total distance, high-speed distance [>19.8 km-h-1] and average acceleration. Linear mixed models and effect sizes identified differences between competition levels. No differences existed between competition levels for any total match physical performance metric. Peak total and high-speed distances demands were similar between competitions for all moving average durations. Interestingly, peak average acceleration demands were lower (SMD = 0.63–0.69) in the youth players across all moving average durations. The data suggest that the development of acceleration and repeat effort capacities is crucial in youth players for them to transition into professional competition

Healthy Body Healthy Mind: Trialling an exercise intervention for reducing depression in youth with major depressive disorder

Introduction: Major Depressive Disorder (MDD) has high prevalence among adolescents and young adults but evidence of any effective treatments is limited. Exercise as an effective treatment for adults has some support but studies in younger populations are lacking. MDD is associated with inflammation and exercise may contribute to reductions in inflammatory marker levels. Therefore the aim of this study was to investigate the feasibility and preliminary efficacy of brief motivational interviewing (MI) plus 12-weeks exercise training as a treatment for MDD in youth. Methods: Youth (15-25 years) with MDD were recruited to participate in a prospective trial investigating exercise as treatment for MDD. Twenty-six participants were screened (telephone then clinical psychology diagnosis) and 13 (9 females) were eligible (MDD from SCID, no psychotic illness, not pregnant, no physical barriers to exercise, not suicidal, no major eating disorder) to participate. Participants completed assessments at baseline and after 12 weeks training, which included questionnaires: the Beck Depression Inventory (BDI-II); blood samples for analysis of inflammatory biomarkers; and fitness measures: VO2max, YMCA bench press test, and a seated horizontal leg press endurance test. Prior to commencing the training program, participants engaged in a motivational interview with a psychologist to enhance engagement with the program. IL-6 was measured by ELISA. The exercise program consisted of small group trainer-led supervised exercise (resistance and endurance) training 3 times a week (1h per session) for 12 weeks, and encouragement to do at least 30min of physical activity on other days. Paired t-tests were used to determine changes from baseline and correlations used to explore relationships between changes in depression scores, training attendance and fitness levels. Results: 12 participants (mean±SD, aged 20.7±1.7 y) completed 12-week assessments; one withdrew due to family issues. Attendance at training averaged 66±25% of sessions; 3 participants completed less than 40% of training sessions. At baseline all participants met the criteria for MDD; at 12 weeks only 2 still met the criteria; depression severity (BDI-II) decreased (p\u3c0.001) from 32±9 to12±10. Aerobic fitness levels did not change with training. YMCA bench press repetitions increased (p\u3c0.001) from 20±11 to 27±11. IL-6 decreased (p\u3c0.05) from 1.39±0.78 to 0.73±0.80 pg.mL-1. Changes in depression symptom scores were significantly correlated (p\u3c0.05) with attendance (r=0.32), improvements in bench press endurance (r=0.65) and changes in IL-6 (r=0.34). Changes in IL-6 were also correlated with attendance (r=0.60) Conclusion: Exercise training is a feasible and potentially effective intervention for MDD in youth and reductions in depression severity are associated with reductions in IL-6

The effect of external loads and biological sex on coupling variability during load carriage.

BackgroundLoad carriage is a fundamental requirement for military personnel that commonly results in lower-limb injuries. Coupling variability represents a potential injury mechanism for such repetitive tasks and its unknown whether external loads and biological sex affect coupling variability during load carriage.Research questionIs there a sex-by-load interaction during load carriage at self-selected walking speeds?MethodsTwenty-six participants (13 males, 13 females) completed three 10-minute treadmill-based trials wearing body-borne external load (0 %BM, 20 %BM, and 40 %BM) at load-specific self-selected walking speeds. A Vicon motion capture system tracked markers with a lower-body direct-kinematic model calculating sagittal-plane segment kinematics of the thigh, shank, and foot across 19 strides. Continuous relative phase standard deviation (CRPv) provided a measure of coupling variability for each coupling angle (Thigh-Shank and Shank-Foot). The CRPv for each load and sex was compared using statistical parametric mapping repeated measures ANOVA and paired t tests.ResultsSignificant sex-by-load interactions were reported for the Thigh-Shank coupling. Males demonstrated no significant load differences in CRPv, however, females displayed significantly higher CRPv in the 40 %BM than the 0 %BM condition. A significant main effect of load was observed in the Shank-Foot coupling, with the 40 %BM having significantly greater CRPv than the other load conditions.SignificanceBoth biological sex and external loads significantly affected CRPv during load carriage at self-selected walking speeds. Females demonstrated greater CRPv at the heavier loads, suggesting that the perturbation from the heavier mass increases coupling variability, which may also be amplified by a greater total passive load due to their relatively higher adipose tissue compared to males. The consistent CRPv in males suggests that higher relative loads may be required to change coupling variability. Collectively, these results suggest that external load affects the coupling variability of males and females differently, providing potential for injury screening and monitoring programs