Effects of post-exercise recovery in a cold environment on muscle glycogen, PGC-1α, and downstream transcription factors

Purpose: The purpose of this investigation was to determine the impact of post-exercise environmental cold exposure on muscle glycogen, PGC-1α, and downstream transcription factors. Methods: Eight males cycled for 1h and recovered in either 7°C (cold) or 20°C (room temp) environment for 4h. Muscle biopsies were obtained pre, post, and 4h post exercise for the analysis of muscle glycogen and mRNA. During recovery participants consumed 1.8gkg^-1 of body weight of an oral dextrose solution immediately following the post biopsy and 2h into recovery. Blood samples were obtained post exercise and at 30, 60, 120, 150, 180, and 240min post exercise for the analysis of serum glucose and insulin AUC. Results: Oxygen uptake was lower during room temp than during cold recovery (0.40±0.05L x min^-1 vs. 0.80±0.12 L x min^-1; p<0.01). There was no effect of temperature on muscle glycogen recovery or glucose AUC. However, insulin AUC was greater during the room temp trial compared to the cold trial (5139±1412 vs. 4318±1272, respectively; p=0.025). PGC-1α gene expression was higher (p=0.029), but ERRα and NRF2 were lower (p=0.019 and p=0.046, respectively) after recovery in the cold. There were no differences in NRF1 (p=.173) or TFAM (p=0.694). Conclusions: This investigation shows no effect of a cold recovery environment on glycogen re-synthesis but does demonstrate reduced ERRα and NRF2 mRNA despite elevations in PGC-1α mRNA when recovery post-exercise takes place in a cold environment.