Differences In Quadriceps Muscle Endurance Between Healthy Males And Females

Abstract

Muscle endurance is critical for many sports, but is rarely assessed. Previous work has used a sustained contraction to measure muscle endurance, finding that females have greater endurance than males. However, a sustained contraction results in greater ischemia and is driven by peak strength. Thus, new clinical assessments of muscle endurance that overcome this challenge are needed. PURPOSE: To evaluate quadriceps endurance between healthy males and females, and compare quadriceps endurance to quadriceps strength. METHODS: 19 healthy subjects (10 M, 26.8 ± 7.6 y; 77.6 ± 12.2 kg; 9 F, 23.8 ± 7.3 y; 60.4 ± 6.2 kg; Tegner 7.0 ± 0.9) participated in this study. Leg dominance was self-reported. Maximum voluntary isometric contraction (MVIC) and endurance were assessed at 90° of flexion on a Biodex dynamometer. Endurance was assessed via 5-second contractions followed by 3-second rests at a target of 70% MVIC. Once the subject’s torque output fell below 50% of the target for 3 repetitions, the test was completed. Endurance was calculated as the area under the torque curve summed across repetitions. Independent t-tests compared differences between males and females. Pearson product moment correlation coefficients assessed the relationship between quadriceps strength and endurance. RESULTS: There were no significant differences in peak isometric strength normalized to body weight (M: 2.6 ± 0.6 Nm/kg, F: 2.6 ± 0.5 Nm/kg), nor was there a relationship between cumulative work and peak strength (p = 0.85, r = -0.05), age (p = 0.22, r = 0.30) or bodyweight (p = 0.31, r = 0.25). Males displayed greater cumulative work than females (M: 242.9 ± 127.3 Nm*s/kg, F: 142.9 ± 71.6 Nm*s/kg, p = 0.05). Both males and females showed significantly greater endurance in the dominant limb (Dominant: 194.9 ± 114.3; Non-dominant: 122.2 ± 55.3; p = 0.003). CONCLUSIONS: The muscle endurance test was not influenced by strength, age, or bodyweight. However, we did find significant differences in limb dominance which could be due to greater use of the dominant limb. In contrast to prior studies, males had greater endurance. We speculate that this could be due to differences in how the muscle reperfuses during rest periods. Future work should assess if these differences carry over after injury and evaluate the physiological determinants for the observed differences.