Grant: Discovery Grants Program - Individual

Our lab has a main research focus on how the human body functions during extreme temperatures. In this field, an important question is why humans cannot exercise as hard or for as long in hot compared to cooler conditions. Historically, the main idea for this is suggested to be the loss of fluid through sweating making the heart work harder. However, many other new ideas have been proposed and demonstrated over the last twenty years, including our lab showing that a hot brain is less able to recruit and activate muscles, even if the skin or muscle itself is kept cool. We have since studied this further by looking at how brain blood flow or brain blood chemistry, both of which may change with high body temperatures, can affect muscle function. However, most of this research is on static muscle movements, which may not be similar to how the brain controls muscle during whole-body exercise. Other labs have shown that higher levels of dopamine, a transmitter molecule in the brain that seems to increase arousal, can cause fit athletes to exercise longer and harder in the heat, and also be able to tolerate higher body temperatures. However, we do not know how dopamine might affect brain blood flow, brain chemistry, or muscle function in the heat. Our proposal has the overall goal of better understanding how body temperature affects muscle function, and has three major themes: 1. Develop muscle tests that can compare static muscle movements with whole-body exercise at normal and high body temperatures. 2. Understand how changes in body temperature, brain blood flow, and brain chemistry affects muscle function during whole-body exercise. 3. Test whether dopamine levels directly affects muscle function at high body temperatures, and study whether any changes are due to changes in brain blood flow or chemistry.