Fig. 4

Relationships between HRV/PA and HRs for cardiac death and all-cause mortality. 3a) smoothing curve fitting of PA in predicting the risks of cardiac death; 3b) smoothing curve fitting of PA in predicting the risks of all-cause mortality; 3c) smoothing curve fitting of HRV in predicting the risks of cardiac death; 3d) smoothing curve fitting of HRV in predicting all-cause mortality. HR, hazard ratio; HRV, heart rate variability; PA, physical activity