Modulation of handgrip strength by contralateral hip flexor motor overflow: randomized controlled trial

Objective: To assess whether the motor overflow generated by the contralateral isometric contraction of the hip flexors attenuates the drop in handgrip strength (HGS) in a repetitive maximal strength protocol in healthy adults. Method: Ninety participants were randomized into control and overflow groups. Handgrip strength was measured in the baseline and test phases using a hand dynamometer. In the test phase, the overflow group performed maximal isometric contractions of the hip flexors simultaneously with the HGS tasks (6 seconds, 9 seconds rest). Multivariate analysis of variance (MANOVA) assessed differences by group, gender, hand and phase. Results: The control group showed a significant reduction in HGS between phases (p<0.05), while the overflow group maintained HGS in the test phase (p>0.05). Effect sizes (Cohen's d=0.71-0.87) indicated medium to high clinical relevance, suggesting neural facilitation by contralateral activation. Conclusion: Motor overflow of the hip flexors supports HGS in repetitive tasks, with potential application in neuromuscular rehabilitation. Strategies based on motor overflow can optimize strength and reduce fatigue in therapeutic protocols.