Thermal Preconditioning Attenuates Exercise-induced Muscle Injury in Mice

Abstract

[Purpose] The purpose of this study was to demonstrate the preventative effect of thermal preconditioning on exercise-induced muscle injury. [Subjects and Methods] Eight-week old male ICR mice were divided into a control group (Cont) and heat stress group (Heat). Mice in the Heat group were immersed in water at 41.5 ± 0.5°C for 20 minutes, 24 h before exercise. Mice performed downhill running at 22 m/min on a —14 degree incline, for 150 minutes. Before and 24, 48, and 72 h after exercise, the quadriceps femoris muscles were removed to analyze heat shock protein 25 (HSP25) levels before exercise and glucose-6-phosphate dehydrogenase (G6PD) activity at all time points. [Result] HSP25 level before exercise was significantly greater in the Heat group than in the Cont group. G6PD activity was significantly increased at 24, 48, and 72 h in the Cont group, and at 48 h in the Heat group compared with before exercise. Increases in G6PD activity in the Heat group were significantly lower than in the Cont group at 24, 48, and 72 h. [Conclusion] These results suggest that thermal preconditioning induces an increase in HSP25 protein and attenuates exercise-induced muscle injury.