The regulation of integrative responses to exercise

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RESEARCH GOALSThe overarching goal of my research program is to understand human adaptations to endurance exercise. Specifically, I am interested in characterizing the systems that convert the stress of exercise into improved skeletal muscle and blood function. I am also interested in understanding the responsiveness of skeletal muscle and blood to relevant exercise and environmental stimuli. BACKGROUNDEnergy expenditure is dramatically increased in exercising muscles compared to rest. To produce this energy, humans must take in additional oxygen from the environment and deliver it to their muscles to burn more fuel (fats and sugars). With regular training, humans are able to exercise at greater intensities and for longer durations. This increased fitness is largely the result of a greater density of fuel-burning mitochondria in the muscles and an increased oxygen-carrying red blood cell volume. The process through which these adaptations occur is complex, but is initiated by brief “signals” that occur in response to each bout of exercise. These signals provoke incremental changes in the organ that, over time, improve its function. The capacity for skeletal muscle and blood to change in response to exercise and environmental stimuli is remarkable, but it is not fully understood. The LONG-TERM OBJECTIVE of my research program is to understand the systems that regulate adaptations in skeletal muscle and blood in response to exercise and reduced oxygen availability. The SHORT-TERM OBJECTIVES build upon my recent progress and are focused on understanding (1) the signals that lead to increased mitochondrial density and red blood cell volume following a single exercise session; and (2) the adaptations that occur with respect to mitochondrial density and red blood cell volume following many exercise sessions. To address these questions, I manipulate the intensity, duration, frequency, and mode of exercise as well as the concentration of oxygen that participants breathe. All studies will be performed in human volunteers and will use cycling as the exercise stimulus. As both men and women will be included in skeletal muscle studies, the influence of sex on mitochondrial density can be determined as well.SIGNIFICANCEThis research will generate knowledge regarding the processes through which humans adapt to exercise, and provide opportunities to train future science leaders. We currently do not fully understand the systems controlling the capacities of skeletal muscle and blood to respond to exercise or environmental stimuli. These studies will help answer these questions and establish new frameworks to answer future questions. Trainees will lead the proposed studies and develop technical and desirable skills that will prepare them for advanced careers in science. Our experiments will provide the foundation for innovative approaches to applied exercise physiology and exercise prescription.