Cardiac Autonomic Function, Cardiovascular Risk and Physical Activity in Adolescents

The aims of this study were to investigate in adolescents: 1) the relationships of physical activity (PA) and cardiorespiratory fitness (CRF) to traditional CVD risk factors, rest and recovery autonomic function; and 2) whether autonomic function strengthens the associations between PA, CRF and CVD risk. Fifty-four (22 girls) adolescents had traditional CVD risk factors, rest and recovery autonomic function evaluated. CRF was measured using a steep ramp cycle test and PA was assessed with accelerometers. Resting HRV (and RMSSD₃₀) and heart rate recovery (T₃₀, HHRτ) were used. Clustered traditional (CVDR_trad) and autonomic (CVDR_auto) risk scores were created and added to form a composite clustered CVD risk score (CVDR_com). PA and CRF were significantly and negatively associated with traditional CVD risk factors. Moderate (MPA) and vigorous (VPA) were positively related to resting RMSSD, and negatively related to T₃₀ and HHRτ (all P<0.05). RMSSD₃₀ recovered faster in the high compared to low median split for VPA. Stronger associations for CVDR_com compared to CVDR_trad were observed for MPA (CVDR_com: r²=0.32, P=<0.001; CVDR_trad: r²=0.17, P=0.002), and VPA (CVDR_com: r²=0.18, P=0.001; CVDR_trad: r²=0.06, P=0.08). These findings strengthen the proposed additional beneficial effects of PA on autonomic function above traditional CVD risk factors.