Strength versus muscle power-specific resistance training in community-dwelling older adults

Background. Loss of muscle power due to normal aging has greater functional impact than loss of strength alone. The present study compared two resistance training programs, one aimed at enhancing muscle power and one at increasing muscle strength, on muscle function and functional performance in older adults. Methods. Sixty-seven healthy, independent older adults (65-84 years) were randomized to a high-velocity varied resistance (HV), constant resistance (ST), or nontraining control (CO) group. Participants trained twice weekly for 24 weeks using six exercises. Dynamic and isometric muscle strength, muscle power, movement velocity, muscle endurance, and a battery of functional performance tasks were assessed. Secondary outcomes included body composition, quality of life, and balance confidence. Results. Muscle strength increased significantly (p <.001) and similarly in the training groups compared to controls (HV, 51.0 +/- 9.0%; ST, 48.3 +/- 6.8%; CO, 1.2 +/- 5.1 %). Peak muscle power also increased with training (p <.05), with no difference between training groups. The change in peak power was 50.5 +/- 4.1%, 33.8 +/- 3.8%, and -2.5 +/- 3.9% in the HV, ST, and CO groups, respectively. Training also improved selected functional performance tasks in the HV and ST groups compared to controls (p <.05), and the HV group reported improved quality of life (p=.018). Conclusion. Muscle power and muscle strength improved similarly using either resistance training protocol, and these changes were accompanied by improvements in several functional performance tasks. However, improvements in the HV group occurred with less total work performed per training session.