Free-living associations between resting heart rate parameters and cardiometabolic health in adults

This study examined associations between multi-day ultra-short resting heart rate (HR) parameters and cardiometabolic health under free-living conditions. Sixty-seven adults (18-59 years, 53% male) completed seven consecutive days of seated 1-min RR interval recordings after waking using a validated chest strap monitor. Log-transformed root mean square of successive differences (LnRMSSD_M) and resting HR (HR_M) were averaged across days and standardized. Cardiometabolic health status was defined as the number of metabolic syndrome (MetS) components present. Associations were assessed using Poisson regression adjusted for age and sex, with additional models including HR_M and HR-adjusted LnRMSSD. Higher LnRMSSD_M was associated with fewer MetS components (IRR = 0.79, 95% CI: 0.64-0.97), whereas higher HR_M was associated with greater metabolic burden (IRR = 1.40, 95% CI: 1.10-1.77). When both variables were included, the association between LnRMSSD_M and MetS was attenuated and no longer significant (IRR = 0.93, 95% CI: 0.72-1.22), while HR_M remained significant (IRR = 1.33, 95% CI: 1.00-1.77). Resting HR parameters obtained through accessible devices were associated with cardiometabolic health, with resting HR accounting for much of the cross-sectional information captured by LnRMSSD. Remote cardiac monitoring may support early cardiometabolic risk identification and longitudinal health surveillance.