Grant: Discovery Grants Program - Individual

The focus of our lab is to understand how changes to the environment - such as temperature and oxygen availability - affects human physiology and performance. Through this grant, we hope to tackle several important questions about how temperature and oxygen affect our muscles during exercise. First, over the past 25 years, we have recognized that either a higher or lower than normal core body temperature can cause early fatigue and reduce exercise ability in many ways. One of the ways this happens is through a direct effect on the muscle itself, or else the brain and nerve's ability to recruit and activate muscle. One of the unavoidable results of heating or cooling a muscle is that the body will increase or decrease, respectively, blood flow to the muscle in order to either release or retain heat in the body. In turn, this change to blood flow can change how much oxygen gets to the muscle. As oxygen is one of the critical fuel for muscles during exercise, it remains unknown whether high or low muscle temperature directly affects muscle function, or whether it is an indirect effect through affecting oxygen availability at the muscle. Second, we know that exercise strengthens muscle, and also that exercise generates a lot of heat within the muscle, causing muscle temperature to rise. At the same time, we are recognizing that repeated passive heat exposure, such as with a sauna or hot bath, can maintain muscle health during periods of inactivity - such as with injury or illness - and also to condition muscle before heavy exercise such as strength training. This leads to an unanswered question of whether any of the benefit from exercise actually comes from this natural repeated heating of the muscle. We will use unique experimental setups to separately control leg muscle temperature, oxygen availability, and exercise in order to study how much temperature affects muscle function when applied acutely or for a long period of time. These two main objectives will also be tested using a common series of muscle tests, from how the muscle responds to the nervous system through to how well the muscles can perform exercise, to allow for the best comparisons across temperature, oxygen, and exercise training. This research will greatly improve our understanding of how temperature can positively or negatively affect the ability of muscle to work. In turn, this will improve our ability to design new ways to maintain muscle health even when exercise may not be possible.