Thermal influences governing oxygen delivery and extraction on skeletal muscle metabolism during exercise

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Human exposure to cold and hot environments influences oxygen (O2) delivery to skeletal muscles and mitochondrial oxidative phosphorylation (OXPHOS) capacity. Fluctuations in O2 delivery to skeletal muscles and O2 extraction in the mitochondria from cold or heat exposure govern mechanisms regulating energy metabolism. Energy metabolism is multi-factorial and modulated by exercise and the environment. While it is known that exercise in a cold and hot environment increases lipids carbohydrates oxidation, respectively, two problems remain: 1) exercise and environmental metabolism have been primarily studied independently with limited insights on combined influences, and 2) the effects of cold and heat on O2 availability and extraction has yet to be comprehensively evaluated during exercise studies, and subsequently linked to energy metabolism. The combined influence of altered O2 delivery to skeletal muscles and O2 extraction in mitochondria and their influence on the metabolic shift in skeletal muscle energy metabolism in extreme environments during exercise is unclear. My research program aims at examining the thermal influences governing O2 delivery and extraction during exercise in the cold and heat, and subsequently determine their roles in regulating skeletal muscle metabolism. Over the next years, a series of studies will be conducted to investigate skeletal muscle tissue oxygenation and oxygen uptake via spatially-resolved spectroscopy technology, in vitro mitochondrial OXPHOS capacity via high resolution respirometry, as well as systemic and intra-muscular energy substrate utilization from muscle biopsies during exercise in the cold and heat. Phase I of my program will included studies specifically targeting fluctuations in O2 delivery and extraction studies during exercise in cold and hot environment. Phase II will focus on studies examining energy metabolism regulating mechanisms based on results of Phase I. This research program is designed to improve our knowledge of human biological systems, more precisely, our understanding of muscle thermal and oxidative physiology and energy metabolism under thermal stress. Beyond this scope, we also aim to implement informative environmentally-based exercise guidelines for the general population in addition to develop safety working guidelines and protocols for occupational workers/military personnel/outdoor sports athletes having to perform physical, sometimes critical tasks under cold or warm conditions. The results stemming from this work will further be used as a benchmark in industrial and technological development to limit the detrimental influences of cold and heat for underground miners, firefighters, food processing workers, construction workers, and other occupational groups.