Sex-specific effects of progressive whole-body vibration combined with active exercises on muscle mass, strength, and function in sarcopenic older adults.

Whole-body vibration (WBV) is a low-strain alternative to resistance training for improving muscle function in older adults, but evidence on progressive frequency protocols and sex-specific effects remains limited. This study investigated the effects of an eight-week WBV program on muscle mass, strength, and functional performance in sarcopenic older adults, with follow-up assessments for sustained benefits. Fifty-six participants (≥ 60 years) classified by EWGSOP2 criteria were randomly assigned to WBV or control groups (n = 28 each, 14 per gender). The WBV group performed dynamic squats with progressive frequency (15-40 Hz) and amplitude (1.2-1.8 mm), while the control group performed identical exercises without vibration. Both groups completed upper and lower limb active exercises thrice weekly for eight weeks. WBV significantly improved skeletal muscle index in females, with a significant time × intervention interaction (p < 0.001) that remained after BMI adjustment (p < 0.001), but not in males (p > 0.05). Physical Performance Test scores had a significant time × intervention interaction in both sex (p < 0.05); after BMI adjustment, the effect remained strong in females (p < 0.001) but was smaller yet significant in males (p = 0.013). Timed Up and Go performance improved in females (interaction: p = 0.001 after adjustment), while the effect in males was not significant (p = 0.972). In females, right leg quadriceps strength increased significantly after BMI adjustment (p < 0.001), with a significant interaction in the left leg (p = 0.034); no significant effects were seen in males (p > 0.05). A reduction in fear of falling (FES-I) was observed in females (p = 0.025), but the pattern of improvement over time did not differ significantly from controls (p = 0.054). For female grip strength, a significant time × intervention interaction was found for the right hand after adjustment (p = 0.002); no significant effects were found in males. While functional improvements were often maintained at follow-up in females, gains in muscle mass and strength showed some decline. These findings indicate that WBV combined with active exercise appears more beneficial for older women with sarcopenia, showing more consistent improvements in muscle mass and strength. Additionally, TUG time reduced below fall-risk threshold. However, sustained training may be necessary to maintain long-term benefits, and larger clinical trials are required to confirm the generalizability of these results.