Locally applied heat stress during exercise training may promote adaptations to mitochondrial enzyme activities in skeletal muscle

• DOI: 10.1007/s00424-024-02939-8
• Publication Date: 2024-03-06T16:02:05Z
• Authors: Ed Maunder; Andrew King; Jeffrey A. Rothsc...; Matthew J. Brick; Warren B. Leigh; Christopher P. He...; Troy L. Merry; Andrew E. Kilding
• Keywords: Male; Adult; Muscle Physiology; Hot Temperature; Physiology; Physiological; 1106 Human Movement and Sports Sciences; 610; 3101 Biochemistry and Cell Biology; Young Adult; 03 medical and health sciences; 0302 clinical medicine; Humans; Adaptation; Muscle, Skeletal; Exercise; 6.7 Physical; Electron Transport Complex I; Electron Transport Complex II; Physical Activity; Skeletal; 0606 Physiology; Heat; Adaptation, Physiological; Mitochondria; Mitochondria, Muscle; 3208 Medical physiology; 3109 Zoology; 1116 Medical Physiology; Muscle; Heat-Shock Response; 31 Biological Sciences

AbstractThere is some evidence for temperature-dependent stimulation of mitochondrial biogenesis; however, the role of elevated muscle temperature during exercise in mitochondrial adaptation to training has not been studied in humans in vivo. The purpose of this study was to determine the role of elevating muscle temperature during exercise in temperate conditions through the application of mild, local heat stress on mitochondrial adaptations to endurance training. Eight endurance-trained males undertook 3 weeks of supervised cycling training, during which mild (~ 40 °C) heat stress was applied locally to the upper-leg musculature of one leg during all training sessions (HEAT), with the contralateral leg serving as the non-heated, exercising control (CON). Vastus lateralis microbiopsies were obtained from both legs before and after the training period. Training-induced increases in complex I (fold-change, 1.24 ± 0.33 vs. 1.01 ± 0.49, P = 0.029) and II (fold-change, 1.24 ± 0.33 vs. 1.01 ± 0.49, P = 0.029) activities were significantly larger in HEAT than CON. No significant effects of training, or interactions between local heat stress application and training, were observed for complex I–V or HSP70 protein expressions. Our data provides partial evidence to support the hypothesis that elevating local muscle temperature during exercise augments training-induced adaptations to mitochondrial enzyme activity.