Effects of 7°C environmental temperature acclimation during a 3-week training period

Abstract

Cold environmental temperatures during exercise and recovery alter the acute response to cellular signaling and training adaptations. Approximately 3 wk is required for cold temperature acclimation to occur. To determine the impact of cold environmental temperature on training adaptations, fitness measurements, and aerobic performance, two groups of 12 untrained male subjects completed 1 h of cycling in 16 temperature acclimation sessions in either a 7°C or 20°C environmental temperature. Fitness assessments before and after acclimation occurred at standard room temperature. Muscle biopsies were taken from the vastus lateralis muscle before and after training to assess molecular markers related to mitochondrial development. Peroxisome proliferator-activated receptor-γ coactivator 1α ( PGC-1α) mRNA was higher in 7°C than in 20°C in response to acute exercise before training ( P = 0.012) but not after training ( P = 0.813). PGC-1α mRNA was lower after training ( P < 0.001). BNIP3 was lower after training in the 7°C than in the 20°C group ( P = 0.017) but not before training ( P = 0.549). No other differences occurred between temperature groups in VEGF, ERRα, NRF1, NRF2, TFAM, PINK1, Parkin, or BNIP3L mRNAs ( P > 0.05). PGC-1α protein and mtDNA were not different before training, after training, or between temperatures ( P > 0.05). Cycling power increased during the daily training ( P < 0.001) but was not different between temperatures ( P = 0.169). V̇o2peak increased with training ( P < 0.001) but was not different between temperature groups ( P = 0.460). These data indicate that a 3-wk period of acclimation/training in cold environmental temperatures alters PGC-1α gene expression acutely but this difference is not manifested in a greater increase in V̇o2peak and is dissipated as acclimation takes place. NEW & NOTEWORTHY This study examines the adaptive response of cellular signaling during exercise in cold environmental temperatures. We demonstrate that peroxisome proliferator-activated receptor-γ coactivator 1α mRNA is different between cold and room temperature environments before training but after training this difference no longer exists. This initial difference in transcriptional response between temperatures does not lead to differences in performance measures or increases in protein or mitochondria.

Exercise- and Cold-Induced Human PGC-1α mRNA Isoform Specific Responses

“…Consistent with our previous environmental cold experimental protocols [ 6 , 8 , 9 , 10 ], average core temperature in the current study was slightly higher in the C than in the RT condition despite a lower skin temperature. This is a compensatory mechanism that overshoots in response to the cold skin temperatures.…”

“…Therefore, PGC-1α-a also included NT-PGC-1α-a , PGC-1α-b also included NT-PGC-1α-b , and PGC-1α-c also included NT-PGC-1α-c . The application of this previously reported approach (i.e., Table 2 ) [ 15 , 22 , 26 ] differed from our laboratory’s previously used gene expression analysis [ 6 , 8 , 9 , 10 ], and, more importantly, was instrumental in allowing us to determine the specific splicing events that occurred within the PGC-1α complex.…”

“…One trial was conducted in cold conditions (C, −2 °C), and the other trial was conducted in room temperature conditions (RT, 20 °C). Trials were separated (1 week) for sufficient washout period [ 10 ]. Testing was done in July (average daily high temperature: 30.8 ± 0.5 °C) to limit the amount of cold acclimation.…”

“…More specifically, aerobic exercise paired with environmental cold exposure has been shown to upregulate the transcription of PGC-1α [ 5 , 6 ]. Some studies have not detected a statistically significant upregulation of PGC-1α in the cold compared to control conditions but did observe non-statistical effects [ 7 , 8 , 9 , 10 ]. Taken collectively, it appears that environmental cold interventions during aerobic exercise enhance the exercise-induced transcription of PGC-1α in humans.…”

“…The purpose of this investigation was to detail the PGC-1α isoform specific response to aerobic exercise in a cold environment. This information will allow us to determine the molecular basis and practical implications of previous work detailing the total PGC-1α response with exercise in the cold [ 5 , 6 , 7 , 8 , 9 , 10 ]. If only investigating total PGC-1α response, specific isoform responses may be diluted, and important implications missed.…”