Leg muscle power is enhanced by training in people with Parkinson's disease: a randomized controlled trial

Objective: To determine the effects of leg muscle power training in people with Parkinson's disease. Design: Randomized controlled trial. Setting: University laboratory (outcome measures and experimental intervention), community (control intervention). Subjects: Community-dwelling people with Parkinson's disease. Interventions: Leg muscle power training using pneumatic variable resistance equipment (experimental) was compared with low intensity sham exercise (control). Both groups exercised twice weekly for 12 weeks. Main measures: Primary outcomes were peak power of four leg muscle groups. Secondary outcomes were measures of muscle strength, mobility, balance and falls. Results: Exercise adherence was high in both groups. Leg muscle power was significantly better in the experimental group than the control group in all four primary outcome measures at 12 weeks after adjusting for baseline values: leg extensors (57.9 watts, 95% confidence interval (CI) 22.0-93.7, p = 0.002); knee flexors (29.6 watts, 95% CI 7.4-51.8, p = 0.01); hip flexors (68.1 watts, 95% CI 19.6-116.5, p = 0.007); and hip abductors (37.4 watts, 95% CI 19.9-54.9, p < 0.001). The experimental group performed significantly better on tests of leg muscle strength (p < 0.001 to 0.07) and showed trends toward better performance in the Timed Up and Go (p = 0.13) and choice stepping reaction time (p = 0.11). There was a non-significant reduction in the rate of falls in the experimental group compared with the control group (incidence rate ratio 0.84, p = 0.76). Conclusions: This programme significantly improved muscle power in all trained muscle groups.