Abstract 10289: Higher Physical Fitness and Lower Measures of Adiposity are Associated With Higher Heart Rate Variability: The Coronary Artery Risk Development in Young Adults (CARDIA) Study
Background: Physical activity and weight are associated with heart rate variability (HRV). However, the relative importance of these 2 factors in determining HRV is unclear. It is also unclear whether more specific measures of physical fitness (graded exercise test duration [GXTd]) and adiposity (waist circumference [WC] and percent body fat by DEXA [%fat]) are associated with HRV. We assessed these associations in a cross-sectional analysis of CARDIA, a biracial observational cohort study.
METHODS: We included 2,402 subjects (mean age 45.3 ± 3.6 years, 58% female, 43% black) with HRV, GXTd, and measures of adiposity obtained in 2005-06. Measures of HRV (standard deviation of all normal RR intervals [SDNN], root mean square of successive differences [rMSSD]) were obtained from resting 30-second 12-lead ECGs. We used multiple linear regression to assess association between GXTd and measures of adiposity with HRV.
RESULTS: The medians (IQR) of SDNN and rMSSD were 26.5 ms (17.4-40.8 ms) and 27.6 (17.8-41.9 ms), respectively. Higher GXTd was significantly associated with higher SDNN and rMSSD after adjusting for measures of adiposity and other confounders. Lower WC and %fat were significantly associated with higher SDNN and rMSSD. However, after additional adjustment for GXTd, WC and %fat were no longer associated with HRV (Table).
Conclusions: Although higher physical fitness and lower measures of adiposity are both associated with higher HRV, the association of physical fitness with HRV is stronger. Further studies to determine the differential effects of improved physical fitness vs. weight loss on HRV are warranted.
- © 2013 by American Heart Association, Inc.