The impact of HIIT and plasma injection on skeletal muscle morphology in aged rats: Insights into age-related muscle remodeling

BACKGROUND: The current study explored the impact of high-intensity interval training (HIIT) and the administration of post-exercise plasma from young-either trained or sedentary-rats on skeletal muscle morphology and circulating irisin levels in aged rats. OBJECTIVE: This study investigates the effects of HIIT and plasma from both sedentary and trained young rats on skeletal muscle morphology, strength, and circulating irisin levels in aged rats. METHODS: Thirty-five aged male Wistar rats were divided into five groups: HIIT, plasma from trained young rats (PT), plasma from sedentary young rats (PC), Control Group (CT), and saline (S). Interventions lasted six weeks; outcome measures included body weight, grip strength, plasma irisin, and muscle histology. RESULTS: Both HIIT and PT significantly increased plasma irisin levels and improved muscle morphology. Plasma interventions reduced body weight; however, grip strength changes were not significant. CONCLUSION: HIIT and plasma from young trained rats may offer protective or restorative benefits against sarcopenia. These findings highlight the therapeutic potential of combining or alternating exercise and plasma-based strategies in elderly populations.