(13) SEX DIFFERENCES IN FATIGUABILITY DURING RESISTANCE EXERCISE IN A RESISTANCE-TRAINED POPULATION

Females demonstrate superior fatigue resistance across a variety of tasks compared to males. However, much of this work has been done during laboratory-specific (i.e. isometric, isokinetic) testing. Much less is known regarding the extent to which sex differences in fatiguability translate to resistance exercise performance.

Purpose: To examine the sex differences in repetition volume and fatiguability following four sets of bicep curls to failure at 50% of 1-repetition maximum (1RM) in a resistance-trained population.

Methods: Twenty habitually resistance-trained subjects (Males: n = 10; Females: n = 10) visited the laboratory on two days separated by ≥ 48 hrs. On the first visit, maximal dynamic strength was determined for the dominant arm. On the second visit, participants completed 4 sets of unilateral dynamic biceps curls to failure at 50% 1RM with their dominant arm, separated by a 2 min rest interval. Maximal voluntary contraction (MVC) strength was recorded immediately before starting exercise and following each set to assess performance fatiguability. Separate mixed factorial repeated measures ANOVA tests (sex × time) were performed on the total repetitions completed across each set and the MVC responses between males and females.

Results: The analyses revealed that for repetitions completed to failure, females performed significantly more repetitions across each set compared to males (Cohen’s d = 0.852; p < 0.001). Additionally, the loss of MVC force across the resistance exercise session was significantly greater for males versus females (Cohen’s d = 0.480; p = 0.046).

Conclusions: During acute resistance exercise at the same relative intensity, females show substantially greater repetition volume than males during four sets of biceps curls performed to failure. Despite the greater repetition volume, females were able to preserve more of their maximal strength (%MVC) across time compared to males. PRACTICAL APPLICATIONS: Current resistance training recommendations may underload strength training prescriptions for females. Since females demonstrate greater repetition volume and less force loss compared to males at the same relative intensity, greater intensities and/or volumes of training may be necessary for resistance-trained females.

Acknowledgements: None