Human mRNA Response to Exercise and Temperature

. The purpose of this research was to determine the mRNA response to exercise in different environmental temperatures. 9 recreationally active males (27 +/- 1 years, 77.4 +/- 2.7 kg, 13.5 +/- 1.5% fat, 4.49 +/- 0.15L center dot min(-1) VO2 max) completed 3 trials consisting of 1h cycling exercise at 60% W max followed by a 3h recovery in the cold (7 degrees C), room temperature (20 degrees C), and hot (33 degrees C) environments. Muscle biopsies were obtained pre, post, and 3h post exercise for the analysis of glycogen and mRNA. Expired gases were collected to calculate substrate use. PGC-1 alpha increased to a greater degree in the cold trial than in the room temperature trial (p=0.036) and the hot trial (p=0.006). PGC1-alpha mRNA was also higher after the room temperature trial than the hot trial (p=0.050). UCP3 and MFN2 mRNA increased with exercise (p<0.05), but were unaffected by temperature. COX was unaffected by exercise or temperature. Muscle glycogen decreased with exercise (p<0.05), but was no different among trials. Whole body VO2 was lower during exercise in the cold than exercise in the heat. However, VO2 was higher during recovery in the cold trial than in the room temperature and hot trials (p<0.05). This study presents evidence of PGC-1 alpha temperature sensitivity in human skeletal muscle.