Cardiovascular autonomic modulation following maximal exercise: Its relationship to race, maximal oxygen uptake, and resting heart rate variability

The purpose of this dissertation was to provide a better understanding of post maximal exercise cardiovascular autonomic function and its relationship to race, VO2max and resting heart rate variability. Heart rate variability (HRV) and heart rate recovery (HRR) are two non-invasive methods to assess cardiovascular autonomic modulation. This dissertation covers three studies. The first study examined the difference in cardiac autonomic function at rest and following maximal exercise between 30 white and 30 black college-age men. The results showed that black men had significantly greater HRV measures at rest, significantly faster heart rate recovery 2-minutes after exercise and significantly greater HRV during a 30-minute post-exercise period compared to the white men. The second study sought to determine the association of race, VO2max, and selected body composition measures to HRR. In this study, seventy-two college-aged men were divided into two groups above and below the mean VO2max of the entire sample (46.32 ml/kg/min) as follows: group 1 (ModFit, n = 36) had a mean VO2max of 39.99 ± 4.01 ml/kg/min; and Group 2 (HiFit, n = 36) had a mean VO2max of 52.66 ± 5.30 ml/kg/min. After comparing the mean heart rate recovery between the two groups, no significant difference was found. However, after controlling for the influence of race, a significant difference between groups in heart rate recovery 2-minutes (HRR2) was revealed, i.e., the HiFit group had a greater HRR2 compared to the LoFit group. Also, backwards linear regression procedures revealed that race was the most significant variable at accounting for the variation in HRR2 and the heart rate at 2-minutes post-exercise. The third study examined the relationship between resting HRV and HRR. The results of this study revealed no association between HRR and any of the resting HRV. However, there were significant associations between resting HRV and the following variables: maximal heart rate, heart rate at 1-minute post-exercise, and the heart rate a 2-minutes post-exercise