Impact of cumulative physical activity and sedentary behavior on early cardiac remodeling in healthy adolescents

Introduction Physical inactivity and sedentary behavior are associated with adverse cardiac remodeling in adults, but evidence supporting these associations in adolescence remains limited. Purpose This study aimed to examine the cumulative effects of accelerometer-derived physical activity and sedentary behavior during adolescence on early subclinical cardiac features assessed by cardiovascular magnetic resonance (CMR). Methods A total of 111 adolescents (55.9% girls) wore a wrist-worn triaxial accelerometer at ages 12, 14, and 16 years to measure physical activity and sedentary behavior. A 3-Tesla CMR scan was performed at the final follow-up to assess cardiac anatomy and function. Multivariable linear regression models were used to examine the associations between cumulative physical activity and sedentary behavior, and CMR-derived metrics. Results Daily step counts were positively associated with indexed end-diastolic volumes of the left ventricle (adjusted β per 1,000 steps/day, 0.54 ml/m·2.7; 95%CI, 0.09 to 1.00; p-value=0.019) and the right ventricle (adjusted β per 1,000 steps/day, 0.65 ml/m·2.7; 95%CI, 0.09 to 1.20; p-value=0.022), as well as with reduced right-ventricular longitudinal strain (adjusted β per 1,000 steps/day, 0.46%; 95%CI, 0.11 to 0.81; p-value=0.010) (Figure 1). A higher number of sedentary bouts was associated with a greater left-atrial active emptying fraction (adjusted β per 1 bout/day, 1.54%; 95%CI, 0.04 to 3.05; p-value = 0.045) (Figure 2). Conclusion Physical inactivity and sedentary behavior during adolescence were independently associated with early markers of ventricular and atrial remodeling. These findings highlight the potential for early cardiac adaptations related to lifestyle behaviors and underscore the importance of promoting active lifestyles from a young age.