ABSTRACT
BACKGROUND: Bradykinesia and postural instability contribute to walking limitations in people with Parkinson's disease (PD), but the contribution of muscle strength to walking speed has not been examined extensively. RESEARCH QUESTION: Does strength of the major lower limb muscles contribute to walking speed over short and long distances in people with PD? METHOD: na. DESIGN: A cross-sectional, observational study. PARTICIPANTS: 50 people with mild PD. OUTCOME MEASURES: Maximum isometric strength of the flexors and extensors of the lower limb was measured using hand-held dynamometry. Flexed posture, postural instability and bradykinesia were measured using the MDS-UPDRS part III. Walking speed was measured during the 10-m Walk Test and 6-min Walk Test. RESULTS: Univariate analysis revealed that age, bradykinesia, flexed posture, and hip, knee and ankle weakness were all significantly correlated with walking speed over short and long distances. Multiple regression analysis revealed that age, bradykinesia, flexed posture and weakness of the hip and knee muscles together accounted for 47% of the variance in walking speed over a short distance, with age (R2 = 0.11, p = 0.003) making a significant independent contribution. Age, bradykinesia, flexed posture and strength of the hip and knee muscles together accounted for 56% of the variance in walking speed over a long distance. Age (R2 = 0.12, p = 0.001), weakness of the hip muscles (R2 = 0.12, p = 0.001) and bradykinesia (R2 = 0.04, p = 0.04) made significant, independent contributions to the variance in walking speed over a long distance. SIGNIFICANCE: In people with mild PD, weakness of the hip muscles and bradykinesia only make a significant relative contribution to walking speed over a long distance. Therefore, in people with normal walking speed over a short distance the 6-min Walk Test could be measured to more effectively identify the impact of motor impairments on walking.
