PROJECT SUMMARY/ABSTRACT This K23 Mentored Patient-Oriented Research Career Development Award will prepare Dr. Catherine Avitabile, a pediatric cardiologist and pulmonary hypertension specialist, for an independent research career focused on exercise interventions to improve lean mass, functional capacity, and quality of life in children with pulmonary hypertension and other heart diseases. Dr. Avitabile’s application is strengthened by her clinical expertise and her prior research demonstrating lean mass (skeletal muscle) deficits in association with worse exercise performance in cardiac patients. Under the mentorship of Drs. Babette Zemel and Stephen Paridon, Dr. Avitabile will pursue a comprehensive career development plan with training in exercise physiology and interventions, body composition assessment, wearable activity monitoring, and qualitative methods. The growing population of pulmonary hypertension survivors report low quality of life and exercise intolerance. Children with pulmonary hypertension engage in less physical activity compared to peers, which is a concern since adult data support exercise as a non-pharmacologic therapy. Exercise training safely improves exercise performance and quality of life in adults with pulmonary hypertension and in one small pediatric study, but therapeutic exercise has not been widely adopted in pediatric pulmonary hypertension. While cardiopulmonary status may limit exercise participation, other barriers to participation have not been explored. It is also unclear how exercise interventions have a clinical effect as they may have multiple targets. Skeletal muscle abnormalities are associated with worse exercise performance in adults with pulmonary hypertension and could be modifiable through exercise interventions. Dr. Avitabile has identified skeletal muscle abnormalities in children with pulmonary hypertension, and these are the focus of her research interests. Exercise interventions that slow symptom progression would improve wellbeing for pediatric pulmonary hypertension survivors and their families. Dr. Avitabile’s proposed research will increase understanding of the health consequences of physical inactivity and identify barriers to exercise in pediatric pulmonary hypertension patients in order to design effective exercise interventions. Aim 1 explores the association between physical inactivity and muscle deficits. Aim 2 employs qualitative interviews to identify barriers to physical activity in order to strengthen intervention design. Aim 3 tests the feasibility and preliminary estimates of efficacy of a home exercise intervention to increase physical activity and improve functional status. The intervention is enriched by data from wearable activity monitors, closely aligned with the priorities of the 2016-2020 NIH-Wide Strategic Plan. This K23 award will support Dr. Avitabile’s pathway to independence as a pediatric cardiologist/pulmonary hypertension expert skilled in exercise physiolog...