Are There Differences Between Sexes in Performance-Related Variables During a Maximal Intermittent Flywheel Test?

Abstract

Background: Isometric and dynamic tasks of low-to-moderate intensities have been used to study sex differences in fatigability; however, maximal exertions with flywheel devices (FDs) have not been used. This study aimed to (1) detect sex differences in fatigue-related performance in a maximal intermittent fatiguing protocol on a FD, and (2) investigate the most sensitive dynamometric and mechanical variables for assessing fatigue in both sexes.

Hypothesis: No sex differences should exist when performing this protocol on a FD.

Study design: Cohort observational study.

Level of evidence: Level 3.

Methods: A total of 34 young adults (17 female/17 male) performed 10 sets of 10 repetitions with 3 minutes of passive recovery of a half-squat exercise on a FD. Inter- and intraset analysis of force, power, velocity, work, and impulse, together with their relative change and slope, were calculated during concentric and eccentric phases. Raw data were also normalized to body mass in the interset analysis. The relative changes in each variable were compared.

Results: Men showed greater and earlier decreases in performance throughout sets (P < .05; η_p² ≥ 0.08), but these differences were not consistent after normalization for body mass (P > .05; η_p² ≤ 0.05). Irrespective of sex and phase, the intraset analysis revealed that relative change was higher in the last set (P ≤ .03; η_p² ≥ 0.14), with power being the most sensitive variable for detecting performance decline (P ≤ .04; η_p² = 0.49).

Conclusion: Women experienced slower and delayed fatigue kinetics than men during a maximal intermittent fatiguing protocol with FD if body dimensionality is not considered. For training purposes, power seems to be the most sensitive and discriminative variable for detecting decreases in performance.

Clinical relevance: Body dimensionality is a key factor that must be considered when comparing both sexes in FDs.