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Observational Study
. 2025 Nov;17(6):1244-1251.
doi: 10.1177/19417381251320574. Epub 2025 Feb 24.

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

Jorge Salse-Batán  1 , Priscila Torrado  1 , Michel Marina  1
Affiliations
Observational Study

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

Jorge Salse-Batán et al. Sports Health. 2025 Nov.

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; ηp2 ≥ 0.08), but these differences were not consistent after normalization for body mass (P > .05; ηp2 ≤ 0.05). Irrespective of sex and phase, the intraset analysis revealed that relative change was higher in the last set (P ≤ .03; ηp2 ≥ 0.14), with power being the most sensitive variable for detecting performance decline (P ≤ .04; ηp2 = 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.

Keywords: eccentric; fatigability; inertial; squat; women.

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Conflict of interest statement

The authors report no potential conflicts of interest in the development and publication of this article.

Figures

Figure 1.
Figure 1.
Relative changes in the peak and averaged values of force, power, and velocity between set1 and set10. Values are mean and SEM. Black dots, men; white dots, women; solid lines, ECC phase; dashed lines, CON phase. All variables represented showed a significant set effect (set1 < set10; P ≤ 0.003). CON, concentric; ECC, eccentric; S1, set1; S10, set10; SEM, standard error of the mean.
Figure 2.
Figure 2.
Sex differences in peak power across the 10 sets of the maximal intermittent flywheel squat test performed by men (black dots) and women (white dots). Values are means and standard deviations. *Significant decrease compared with set1 in men. †Significant differences between sexes.
See this image and copyright information in PMC

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