Effects of low-intensity pulsed ultrasound on muscle mass and Fndc5 mRNA expression in aged male mice

Sarcopenia, the progressive loss of skeletal muscle mass and function with aging, is a growing public health concern. Conventional treatments such as exercise, pharmacological agents, and nutritional support offer limited efficacy, especially in older populations with reduced mobility or comorbidities. This study aimed to evaluate low-intensity pulsed ultrasound (LIPUS) as a novel, non-invasive therapeutic approach for age-related muscle atrophy. LIPUS was applied to the right hindlimbs of young (12-week), middle-aged (60-week), and aged (95-week) mice for 8 weeks. Muscle weights and mRNA expression levels were analyzed. In aged mice, LIPUS significantly increased gastrocnemius muscle mass and upregulated Fndc5 and Opa1 mRNA, genes associated with mitochondrial function and muscle regeneration. These findings suggest that LIPUS may serve as a safe, non-invasive intervention to counteract sarcopenia by promoting muscle growth and mitochondrial gene activation in aged skeletal muscle.