Human skeletal muscle mRNA response to exercise in a hot environment

Abstract

Mitochondrial adaptation is important for both maintaining optimal health as well as improving athletic The purpose of this investigation was to determine the effects of exercise in a hot environment on mitochondrial biogenesisrelated gene expression in human skeletal muscle. Recreationally-active males (n = 9, 25 ± 4 y, 179 ± 4 cm, 76.2 ± 8.0 kg, VO2 peak 4.39 ± 0.82 L · min-1, 13.4 ± 3.3% body fat) completed two experimental trials in which they cycled for 1 h at 60% of Wmax in an environmental temperature of either 20º C (N) or 33º C (H). Muscle biopsies were obtained from the vastus lateralis pre- and 3 h post-exercise for determination of gene expression. Relative oxygen consumption was higher during exercise in H (69.8 ± 4.7%) than N (64.5 ± 5.7%; p = 0.004), as was HR (H: 163 ± 9 bpm, N: 151 ± 9 bpm; p \u3c 0.001). There was a tendency for expression of PGC-1α to be lower following H than N (p = 0.083). Expression of ERRα (p = 0.009), GABPA (p = 0.010), MEF2A (p = 0.080), NRF-1 (p = 0.004), and VEGF (p = 0.004) was blunted following exercise in H as compared to N. Expression of PPARG, SIRT-1, and TFAM was unaffected by temperature or exercise (p = 0.305, p = 0.103, p = 0.410, respectively). These data demonstrate that exercise in a hot environment blunts expression of several genes related to mitochondrial biogenesis