Relative Handgrip Strength as the Primary Determinant of Fatigue Resistance in Young Adults

Biological sex differences in strength, fat content, and cross-sectional area may influence fatigue resistance in young adults. This study examined the relationship between fatigue resistance and handgrip strength, body composition, viscoelastic properties, and hand-forearm anthropometry in university students. A cross-sectional study was conducted with 57 participants underwent assessments of handgrip strength, body composition (bioimpedance), forearm muscle mechanical properties, and anthropometry. Fatigue resistance during sustained maximal voluntary isometric contraction (MVIC) was evaluated as the time required for force to decline to 75% and 50% of MVIC. Pearman correlations and ANCOVA models were applied (p < 0.05). Men exhibited higher absolute and relative handgrip strength and greater fatigue resistance at both thresholds. Relative handgrip strength was the strongest and most consistent predictor of fatigue resistance (r = 0.67), outperforming body composition, viscoelastic properties, and anthropometric measures. At FR75%, sex and relative strength both predicted fatigue resistance; however, at FR50%, the sex effect disappeared once relative strength was controlled, indicating that observed sex differences were largely attributable to differences in strength rather than biological sex per se. Body composition showed limited predictive value: only fat mass modestly predicted FR50%, while percent body fat and fat-free mass were not associated with fatigue resistance. Forearm muscle tone and stiffness, despite being higher in men, did not explain variability in fatigue resistance. Anthropometric dimensions demonstrated minor associations but contributed little explanatory value beyond strength. Overall, the findings indicate that relative strength is the primary determinant of fatigue resistance, while sex, body composition, muscle mechanical properties, and anthropometry add minimal additional insight.