Regulation of skeletal muscle mitochondrial fuel utilization during exercise

Skeletal muscle exhibits remarkable metabolic plasticity, with mitochondria playing a central role in adapting to energy demands during exercise. These organelles form a dynamic and specialized system capable of remodeling to meet metabolic challenges. Recent studies demonstrate that exercise not only stimulates mitochondrial biogenesis but also engages finely tuned quality-control mechanisms to sustain energy efficiency and performance. A key adaptation is mitochondrial fuel flexibility, the capacity to switch between lipid and carbohydrate oxidation, which underlies endurance and metabolic health. Importantly, efficient lipid utilization, rather than low lipid content, explains why trained muscle can accumulate lipids while remaining insulin sensitive. Here, we review emerging insights into how exercise reprograms skeletal muscle mitochondria to optimize fuel use and highlight implications for metabolic disease.