AMPK/mTOR balance during exercise: implications for insulin resistance in aging muscle

Age-related reductions in skeletal muscle insulin responsiveness promote metabolic dysregulation and contribute to an elevated probability of type 2 diabetes onset. The malfunction of nutrient-responsive signaling routes, specifically AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR), constitutes a central component of this biological process. The integrated activity of these kinases in controlling energy dynamics, protein formation, and glucose processing is fundamental to ensure metabolic homeostasis in skeletal muscle tissue. Through its modulation of AMPK and mTOR pathways, exercise helps reinstate signaling equilibrium and supports better insulin efficacy in aging skeletal muscle. This review explores the molecular mechanisms by which different forms of exercise-endurance, resistance, and combined training-modulate the AMPK/mTOR axis in aging muscle. This analysis focuses on exercise-induced AMPK signaling as a catalyst for mitochondrial development, enhanced glucose processing, and intensified fatty acid breakdown, while also temporally coordinating mTOR activity to support muscle maintenance without exacerbating insulin resistance. By integrating insights from aging biology, exercise physiology, and molecular metabolism, this review highlights the therapeutic potential of targeting AMPK/mTOR signaling through physical activity to combat insulin resistance in the elderly.