Efficacy and safety of a simple home-based resistance exercise program for older adults with low muscle mass: a prospective longitudinal clinical trial.

Low muscle mass is a common condition among older adults that adversely affects strength, physical performance and quality of life. This study aimed to investigate the efficacy and safety of a simple home-based resistance exercise program for older adults with low muscle mass, which was defined as appendicular skeletal mass (ASM) measured by bioimpedance analysis lower than 5.7 kg/m2 in females, and lower than 7.0 kg/m2 in males. This home-based resistance exercise program targets 10 muscles with a frequency of 3-5 days/week for 24 weeks. ASM, grip strength, gait speed and functional reach were measured at baseline, 3 and 6 months. The same four outcomes were then remeasured at 9 months to assess long-term effects. A total of 112 participants (average age: 70 years) were recruited. The mean difference between baseline and 6 months was statistically significant for all outcomes, including ASM [0.12 kg/m2: 95% confidence interval (CI), 0.05-0.18; P = 0.001], gait speed (0.19 meter/s: 95% CI, 0.14-0.25; P < 0.001), grip strength (2.06 kg: 95% CI, 1.32-2.80; P < 0.001), and functional reach distance (4.18 cm: 95% CI, 3.18-5.18; P < 0.001). Change over time for all main outcomes from baseline to 9 months also showed statistically significant improvement. The most commonly reported adverse events were muscle pain, joint pain and fatigue. The majority of participants (90-93%) had good exercise compliance, even at the end of the study. In conclusion, this 24-week simple home-based resistance exercise program significantly improved all main outcomes with low adverse events, and most participants continued the program after the end of the intervention.