Search

The ability to produce muscle power during sprint acceleration is a major determinant of physical performance. The comparison of the force-velocity (F-v: theoretical maximal force, F 0 ; velocity, v 0 and maximal power output, P max ) profile between men and women has attracted little attention. Most studies of sex differences have failed to apply a scaling ratio when reporting data. The present study investigated the sex effect on the F-v profile using an allometric model applied with body mass (BM), fat-free mass (FFM), fat-free mass of the lower limb (FFMLL), cross-sectional area (CSA) and leg length (LL) to mechanical parameters. Thirty students (15 men, 15 women) participated. Raw velocity-time data for three maximal 35 m sprints were measured with a radar. Mechanical parameters of the F-v relationship were calculated from the modelling of the velocity-time curve. When F 0 and P max were allometrically scaled with BM (p = 0.538; ES = 0.23) and FFM (p = 0.176; ES = 0.51), there were no significant differences between men and women. However, when the allometric model was applied to P max with FFMLL (p = 0.015; ES = 0.52), F 0 with CSA (p = 0.016; ES = 0.93) and v 0 with LL (p ≤ 0.001; ES = 1.98) differences between men and women persisted. FFM explained 83% of the sex differences in the F-v profile (p ≤ 0.001). After applying an allometric model, sex differences in the F-v profile are explained by other factors than body dimensions (i.e., physiological qualitative differences)., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: This work studied the acute effects in healthy adults of evening exercise timing on their quality of sleep and dietary intake over the following 12 h., Methods: Sixteen men and women, (age: 22.3 ± 1.4 years; BMI: 20.8 ± 1.4 kg/m 2 , intermediate chronotype) took part in three randomized crossover sessions spread over three consecutive weeks: control session (CTL), 1 h exercise session at 6:30 pm (E6:30) and 1 h exercise session at 8:30 pm (E8:30), in which exercise finished 4 h and 2 h before habitual bedtime, respectively. Exercise was an outdoor run at 60% HR maxth . Energy expenditure and sleep were ambulatories monitored by accelerometry under free-living condition. Ad-libitum dinner and breakfast were used to measure subsequent energy intake and proportion of that energy derived from each macronutrient., Results: Evening exercise did not disrupt sleep. Improvement in sleep quality compared to the control condition was observed only when exercise was performed 4 h before habitual bedtime (WASO: p < 0.01; SE: p < 0.02). Interestingly, our results give insight into differences in sleep parameters response to evening exercise between habitually poor and good sleepers mainly when it comes to sleep efficiency and wake after sleep onset (all p < 0.01). There was no difference in calorie intake from ad-libitum dinner and breakfast. However, an association between improvement in sleep efficiency from acute exercise and reduction of energy intake the following morning was found., Conclusion: Early evening exercise could offer a useful alternative for achieving better sleep in healthy young adults especially when it comes to poor sleepers.

The effect of exercise on sleep remains controversial in athletes especially in junior athletes. This study tested the acute effect of additional intense rugby training on sleep, next-day dietary intake, and physical performances in adolescent rugby players compared to a day with regular exercise. 17 male rugby players in the national under-17 category (age: 15.7 ± 1.1 years, height: 1.78 ± 0.1 m, weight: 84.4 ± 13.6 kg, BMI: 26.6 ± 3.8 kg/m 2 , fat mass: 14.5 ± 3.4%, VO 2max Yo-Yo test: 52.1 ± 4.4 mL/min/kg, evening chronotype) took part in this study. The athletes completed two 36-h experimental sessions in random order: a regular exercise program (REP) vs. an intensified exercise program (IEP) at a 1-week interval. Physical activity and sleep data were collected using accelerometers. Performance tests were conducted the next morning after an ad libitum breakfast. Sleep improved during intensive training (TST: + 26 min, SL: - 4%, WASO: - 39%, SE: + 8.5%) with moderate effect size. There was no next-day difference in calorie intake from breakfast, but macronutrient composition shifted toward proteins (regular: 15.4 ± 6.1% vs. intensive: 18.9 ± 7.4%, ES = - 0.650 [- 1.13;  - 0.18]). There were no significant differences in Wingate test performance or spatial awareness task time. However, performance in submaximal tests improved. Acute intensified training results in increased sleep duration and quality without disturbing next-day performance or dietary intake in young rugby players.