The effects of biological sex on fatigue during and recovery from resistance exercise.

Background: Guidelines for resistance training prescription do not often consider sex as it relates to exercise prescription, despite its potential influence on responses to and adaptations following resistance training. If there are sex differences in the rate at which males and females fatigue during a resistance training session, or the rate at which they recover from resistance training between sessions, optimal resistance training volume may differ between the sexes. The purpose of this study was to investigate sex differences in fatigability and recovery from dynamic resistance exercise. Methods: Male and female subjects with at least one year of bench press experience (N = 21 males and 21 females) performed a fatigue protocol consisting of barbell bench press with 75% 1RM loads for sets of five repetitions, with 90 seconds between sets, until the point of concentric failure. Recovery was monitored for the subsequent 72 hours using subjective ratings of soreness for the pectoral muscles, triceps, and anterior deltoids, and estimated 1RM strength derived from load-velocity profiles. Results: The female subjects completed more reps during the fatigue protocol (females: 58.3 ± 27.3; males: 29.6 ± 10.6; p = 0.0001), but post-training soreness and recovery of estimated 1RM strength did not significantly differ between sexes (p > 0.05). Conclusion: Our results suggest that females fatigue slower than males during multiple sets of bench press yet appear to recover from training at the same rate in spite of completing a higher relative workload. Furthermore, the difference in performance during the fatigue protocol appears to be attributable to the female subjects recovering more quickly during the rest intervals, rather than fatiguing more slowly while performing each set.