Maximal Handgrip Strength as a Measure of General Functional Capacity Rather than Parkinson's Disease-Specific Impairment.

Background/Objectives: Gait impairment and reduced handgrip strength are common in Parkinson's disease (PD), but their relationship remains unclear. This study examined whether associations between handgrip force and gait reflect PD-specific impairment or broader functional capacity. Methods: In this cross-sectional study, 45 individuals with PD and 51 healthy older adults completed unilateral maximal isometric handgrip testing and overground gait assessment at preferred and maximal speed. Handgrip variables included peak force (PF), rate-of-force development (RFD), and impulse. Gait speed, cadence, and step length were recorded. Results: PF was significantly associated with gait speed and step length in both groups, especially under maximal-speed conditions. RFD and impulse were not significantly associated with gait performance in either group. Compared to controls, participants with PD showed poorer gait performance, with lower preferred walking speed and shorter step length in both gait conditions. Within the PD group, PF was lower on the more-affected side than on the less-affected side, whereas most RFD and impulse variables showed no side differences. Conclusions: Maximal handgrip strength, but not upper-limb RFD or impulse, was associated with key gait outcomes in both PD and healthy older adults. These findings suggest that handgrip strength may reflect general functional capacity rather than a PD-specific neuromuscular mechanism and support its use as a practical clinical indicator of mobility-related function.