Reduced muscle power is associated with slower walking velocity and falls in people with Parkinson's disease.

PURPOSE Muscle strength (force) and power (force x velocity) are reduced in Parkinson's disease (PD). Reduced muscle power is associated with slower walking velocity and falls in the older population, but these associations in people with PD have not previously been investigated. This study investigated the relationships between leg extensor muscle power and strength with walking speed and past falls in people with PD. PARTICIPANTS AND METHODS Forty people with mild to moderate PD were assessed. Walking velocity was measured over 10 m and the number of falls the participant reported having in the past 12 months was recorded. Leg extensor muscle power and strength were measured using a Keiser leg press machine. RESULTS Muscle power explained more than half of the variance (R(2) = 0.54) in walking velocity and remained significantly (p < 0.05) associated with walking velocity in models which included Unified Parkinson's Disease Rating Scale (UPDRS) motor scores. Participants with low muscle power were 6 times more likely to report multiple falls in the past year than those with high muscle power (OR = 6.0, 95% CI 1.1 to 33.3), though this association between falls and power was no longer significant in models which included UPDRS motor scores (p = 0.09). CONCLUSION Muscle power is a significant determinant of walking velocity in PD even after adjusting for UPDRS motor score. Muscle power training warrants investigation in people with PD.