The Association between Cardiac Energy Metabolism and Physical Activity during Adolescence and Early Adulthood

A greater understanding of the mechanistic associations among subclinical cardiac dysfunction, metabolism, and physical activity may facilitate the early identification and treatment of premature cardiovascular disease originating during late adolescence, thereby preventing the progression of cardiovascular disease in adulthood. The present set of studies involved the implementation of novel cardiac 31Phosphorus Magnetic Resonance Spectroscopy in adolescents and young adults at The Hospital for Sick Children. These pilot studies are the first to characterize cardiac energy metabolism in both healthy and overweight cohorts during adolescence and early adulthood, as well as the first to explore the relationships among physical activity, cardiac and skeletal muscle energy metabolism, and cardiac function. Notably, reproducibility of primary study measures, including cardiac (i.e., PCr/ATP-beta) and skeletal muscle energy metabolism (i.e., PCr recovery half-time), was explored (Study A). A positive association was demonstrated between cardiac energy metabolism and skeletal muscle energy metabolism, independent of moderate-to-vigorous physical activity levels and peak exercise performance (Study B). A positive association was also observed between novel measures of cardiac energy metabolism (resting cardiac PCr/ATP-beta) and cardiac function (i.e., resting LV torsion and longitudinal strain during a graded exercise protocol) in active healthy weight and overweight adolescents, independent of body mass index percentile and moderate-to-vigorous physical activity levels (Study C). A crossover study intervention, including nine consecutive days of remote ischemic preconditioning (RIPC) and high-intensity interval exercise, was not associated with improvements in peak exercise performance or cardiac energy metabolism (Study D). Larger, randomized clinical research studies ultimately need to be conducted to substantiate these study findings, as well as to investigate the longer-term effect of chronic RIPC and exercise on energy metabolism and cardiovascular health in both sedentary and clinical cardiology cohorts.Ph