Effects of exercise and/or β-hydroxy-β-methylbutyrate supplementation on muscle mass, muscle strength, and physical performance in older women with low muscle mass: a randomized, double-blind, placebo-controlled trial

Background: The interaction between exercise and nutritional supplementation is unclear among older adults at risk of sarcopenia. Objectives: We aimed to examine if beta-hydroxy-beta-methylbutyrate (HMB) supplementation enhances the effects of exercise on muscle mass, strength, and physical performance and observe potential residual effects in older women with low muscle mass. Methods: This 12-wk, randomized, double-blind, placebocontrolled, 2 x 2 factorial design (exercise-only, HMB-only, both, and none) trial included 156 women aged 65-79 y with skeletal muscle index <5.7 kg/m(2), and was followed by a 12-wk observational period. Resistance training twice weekly or education programs every 2 wk and calcium-HMB (1500 mg) or placebo supplements daily were provided. The primary outcome was the change in muscle mass from baseline to postintervention. Secondary outcomes included changes in muscle strength and physical performance. Results: In total. 149 and 144 participants completed the assessment at weeks 12 and 24, respectively. ANOVAs based on the intention-to-treat principle showed no significant interactions between exercise and HMB on any primary outcomes. The main-effect analyses revealed that exercise improved the usual and maximal gait speed by 0.16 m/s (95% CI: 0.10, 0.21 m/s) and 0.15 m/s (95% CI: 0.09, 0.22 m/s), respectively; the knee extensor and hip adductor strength by 22.0 N (95% CI: 10.1, 33.9 N) and 21.8 N (95% CI: 12.9. 30.7 N), respectively; and timed up-and-go and sit-to-stand time by -0.5 s (95% CI: -0.7. -0.3 s) and -1.7 s (95% CI: -2.1, -1.3 5), respectively, relative to education. HMB improved usual gait speed by 0.06 m/s (95% CI: 0.01. 0.11 m/s) relative to placebo. Most improvements disappeared during the subsequent 12-wk observation period. Conclusions: HMB additively improved gait performance with negligible benefit and provided no enhancements in the effects of exercise on other outcomes. Exercise appeared to be the only effective intervention to improve outcomes in older women with low muscle mass.