THE METABOLIC EFFECTS OF ENERGY BALANCE AND CARBOHYDRATE DEFICIT AFTER EXERCISE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Obesity and its related health complications, including insulin resistance, has become a major public health problem in our society. A single session of exercise has been shown to improve insulin sensitivity for hours and even days after exercise. Additionally, energy balance (i.e., energy intake energy expended) and carbohydrate balance (i.e., ingesting enough carbohydrate to maintain muscle and liver glycogen content) can also affect insulin sensitivity. Therefore, because exercise affects energy balance and carbohydrate balance, it is difficult to determine how exercise improves insulin sensitivity. The purpose of this proposed project is to determine the contributions of total energy balance, carbohydrate balance, and exercise, per se, on the exercise-induced enhancement of insulin sensitivity. Ten young, lean, healthy volunteers will complete four separate trials. Three trials will include an identical exercise session followed by different diets designed to alter total energy balance and carbohydrate balance to allow for the measurement of the role each variable plays in the metabolic responses to exercise. A fourth trial will serve as a non-exercise control. Additionally, because alterations in fat mobilization are associated with impaired insulin sensitivity and fat mobilization is known to be influenced by exercise and diet, we will measure the release of fat from storage in fat cells and how well it is taken up to be used by muscle. In the end, these experiments will provide insight into how altered dietary conditions after exercise impact insulin sensitivity and lipid metabolism. Identifying the factors that contribute to the exercise-induced enhancement of insulin sensitivity may lead to improved therapeutic approaches to conditions associated with obesity and insulin resistance.