Environmental temperature and glycogen resynthesis

This study investigated the effects of hot (H) and room temperature (RT) recovery environments on glycogen resynthesis. Nine male participants completed two trials, cycling for 1h in a temperature-controlled chamber (32.6°C), followed by 4h of recovery at 32.6°C (H) or 22.2°C (RT). Rectal temperature was continuously recorded. A carbohydrate beverage (1.8g/kg bodyweight) was supplied at 0 and 2h post-exercise. Muscle biopsies were taken immediately, 2h, and 4h post-exercise for glycogen analysis. Blood samples were taken at 30, 60, 120, 150, 180, and 240min into recovery for glucose and insulin analysis. Expired gas was collected at 105min and 225min into recovery to calculate whole body carbohydrate oxidation. Average core temperature, whole body carbohydrate oxidation, and serum glucose at 120, 150, 180 and 240min was higher in H compared to RT (p<0.05). Muscle glycogen was higher in RT vs. H at 4h (105±28 vs. 88±24mmolkg¹ wet weight, respectively; p<0.05), but no different at 0 and 2h. There was no difference in serum insulin. These data indicate the importance of minimizing the exposure to heat after exercise to improve recovery, specifically to improve glycogen resynthesis.