Effects of local skeletal muscle cooling prior to acute exercise and endurance training on mitochondrial adaptation in mice.

While post-exercise cooling is known to enhance skeletal muscle adaptations, the effects of pre-exercise cooling remain unclear. This study investigated whether local muscle cooling immediately before exercise augments training-induced mitochondrial biogenesis in male C57BL/6 mice. Pre-exercise cooling involved 6 cycles of 6 min at 13°C followed by 4 min at 35°C on one hindlimb for 60 min before treadmill running. Acutely, this pre-cooling protocol increased exercise-induced PGC-1α mRNA expression by ∼13 % (p < 0.05) compared to exercise alone; this effect was abolished when cooling and exercise were separated by 3 h. Chronically, over 4 weeks, combined pre-cooling and exercise training significantly enhanced mitochondrial enzyme activities: citrate synthase (both main effects) and β-hydroxyacyl-CoA dehydrogenase (+23.9 % compared with exercise alone). However, mitochondrial structural protein levels remained unchanged. These results indicate that pre-exercise cooling promotes mitochondrial enzymatic adaptations in skeletal muscle, potentially offering a practical strategy to optimize the outcomes of endurance training.