Modification of palmar grip strength induced by overflow contralateral to hip contraction

Abstract

Introduction: Neurofunctional rehabilitation often employs various approaches to enhance recruitment and muscle strength through overflow, a phenomenon that amplifies the motor response of homologous muscles in the contralateral segment. overflow has been well documented in the literature, particularly in techniques like FNP and cross-education. The phenomenon of overflow is known to facilitate muscle activity in muscles that are not actively stimulated, resulting in unintentional contractions during a resisted isometric activity. Objectives: The objective of this study was to investigate the overflow mechanisms of non-homologous contralateral muscles of the lower limb during an instructed handgrip task. Methods: A total of 90 individuals, with a motor preference for their right upper limb (RUL), were divided into control (CG) and resisted isometry group (RIG) and underwent a protocol involving three maximal hand grip contractions with their RUL and LUL. In assessment 2, the CG performed the same protocol as baseline, while the RIG group performed three maximal isometric contractions of left hip flexion with three maximal contractions of hand flexion with their RUL. statistical analysis was conducted by a multiple comparison analysis of variance with P < 0.05. Results: Observing the data from evaluation 1, both the CG and RIG showed a reduction in strength between the third and first attempt for both the left and right upper limbs (F = 1.07, F = 0.68, respectively). In evaluation 2, the decrease occurred only for the CG in both upper limbs (F = 0.15, F = 1.29, respectively). Conclusion: Our study revealed that maximal muscle strength was maintained in RIG individuals during assessment 2, indicating the existence of overflow when performing an isometric hip flexion task concomitantly with the palmar grip.