Sex Differences in the Acute Effects of Early Partial and Total Sleep Deprivation on Strength, Power, and Endurance...

Background: Sleep is essential for athletic performance, yet the specific effects of sleep deprivation are not well defined. Evidence in resistance-trained populations is limited regarding sex-specific responses and velocity-based performance across different loads. Purpose: This study examined sex differences in the impact of total (0 h) and partial (4 h) sleep deprivation versus normal sleep (8 h) on strength, power, and endurance performance in resistance-trained individuals. Methods: Twenty-four resistance-trained participants (male/female, 12/12; age: 22 ± 3 years) completed a randomized, cross-over, counterbalanced trial including one baseline control night (8 h at home sleep) and three experimental conditions in the laboratory: (a) 8 h sleep (NS), (b) 4 h sleep (ESD), (c) 0 h sleep (SD). Strength was assessed at 25%, 50%, 75%, 90% and 100% 1RM for bench press and back squat (half-squat depth, ~90° knee flexion), in a Smith machine, followed by a muscular endurance test at 65% 1RM (set-to-failure). Isometric strength and vertical jump test were also performed. Results: At 50% 1RM, significant sleep and sleep-by-sex effects were observed for V_mean in both exercise (p < 0.05, η_p² > 0.09), an effect only noted in males, with reduced performance under ESD and SD compared to NS (7-13%, p < 0.05, g > 0.50). In the muscular endurance test, sleep and sleep-by-sex effects were found (p < 0.05, η_p² < 0.22), an effect only found in females during the back squat, showing performance declines in V_mean in ESD and SD compared to NS (7-12%, p < 0.05, g > 0.2). Conclusions: Total and partial sleep deprivation impairs muscular performance differently by sex. Males experienced reduced strength at moderate loads, while females showed declines in muscular endurance.