RESUMO
BACKGROUND: We compared the effects of two uniquely different lower extremity power training interventions on changes in muscle power, physical performance, neuromuscular activation, and muscle cross sectional area in mobility-limited older adults. METHODS: Fifty-two subjects (78±5 years, short physical performance battery score: 8.1±1) were randomized to either 16 weeks of progressive high velocity resistance training performed at low external resistance (40% of the 1-repetition maximum [1-RM] [LO]) or high external resistance (70% of 1RM [HI]). Both groups completed three sets of leg and knee extension exercises at maximum voluntary velocity, two times per week. Neuromuscular activation was assessed using surface electromyography and muscle cross sectional area (CSA) was measured using computed tomography. RESULTS: At 16 weeks, LO and HI exhibited significant and similar within-group increases of leg extensor peak power (~34% vs ~42%), strength (~13% vs ~19%), and SPPB score (1.4±0.3 vs 1.8±0.3 units), respectively (all P < .03). Improvements in neuromuscular activation occurred in LO (P = .03) while small gains in mid-thigh muscle CSA were detected in LO (1.6%, P = .35) and HI (2.1%, P = .17). No significant between-group differences were evident for any measured parameters (all P > .25). CONCLUSIONS: High velocity resistance training with low external resistance yields similar improvements in muscle power and physical performance compared to training with high external resistance in mobility-limited elders. These findings may have important implications for optimizing exercise interventions for older adults with mobility limitations.
