Short-time resistance training enhances sleep quality in obese and non-obese young women

Purpose: The purpose of this study was to examine the effects of short-term resistance training on sleep quantity and quality in young women, according to their body fat. Methods: Thirty-five young women were randomly assigned based on their body fat levels, using the 90th percentile of fat mass as a criterion, with a threshold set at ≥ 21 kg of fat mass for the obese group (n = 16) and < 21 kg of fat mass for the non-obese group (n = 19). Subjective sleep quality was evaluated using the Pittsburgh Sleep Quality Index (PSQI) at pre and post a progressive six-week full-body resistance training (RT). Results: Post-intervention analysis showed a reduction in the overall sleep score (p = 0.006, η2 = 0.21), improvement in subjective sleep quality (p < 0.001; η2 = 0.357) and a decrease in sleep disturbances (p = 0.034; η2 = 0.129). However, no interaction between group x training for sleep parameters and body composition was observed (p > 0.05). There were no significant correlations between sleep quality, fat mass and fat-free mass in both groups investigated (p > 0.05). Conclusion: Six-weeks of RT improved subjective sleep quality and reduced sleep disturbances in young women, regardless of the amount of fat mass. Sleep variables were not associated with changes in body composition.