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-1 alpha, and downstream transcription factors. Methods: Eight males cycled for 1 h and recovered in either 7 degrees C (cold) or 20 degrees C (room temp) environment for 4 h. Muscle biopsies were obtained pre, post, and 4 h post exercise for the analysis of muscle glycogen and mRNA. During recovery participants consumed 1.8 g kg(-1) of body weight of an oral dextrose solution immediately following the post biopsy and 2 h into recovery. Blood samples were obtained post exercise and at 30, 60, 120, 150, 180, and 240 min 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 +/- 0.05 Lx 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-l alpha gene expression was higher (p = 0.029), but ERR alpha 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 ERRct and NRF2 mRNA despite elevations in PGC-l alpha mRNA when recovery post-exercise takes place in a cold environment. (C) 2013 Elsevier Inc. All rights reserved.