Heart rate variability and cardiorespiratory fitness in African American men

Heart rate variability (HRV) has become a widely used indicator of cardiovascular autonomic control. Previous research has shown HRV to be greater in subjects with higher levels of cardiorespiratory fitness. However, the association of HRV and cardiorespiratory fitness in African American (AA) subjects is not known. This investigation aimed to determine if norm‐referenced cardiorespiratory fitness groupings would reflect differences in HRV in AA men. Forty college‐aged AA men had their resting HRV assessed via electrocardiography and later completed a graded maximal exercise treadmill test. Individuals were stratified according to VO2 peak, those above 43.9 ml·kg −1 ·min −1 (50 th percentile for college‐aged men) (Group A) and those below (Group B). HRV differed between groups A and B for low frequency (LFnu; 32.5 ± 7.4 ms 2 vs. 37.9 ± 8.6 ms 2 ), high frequency (HFnu; 52.3 ± 7.6 ms 2 vs. 47.5 ± 6.6 ms 2 ), and LFnu:HFnu (0.6 ± 0.2 vs. 0.8 ± 0.2) respectively ( P < 0.05). These data suggest that differences in cardiorespiratory fitness levels reflect differences in autonomic control of the cardiovascular system in college‐aged AA males. Supported by Auburn University Montgomery & The University of Alabama .