Average heart rate, heart rate variability and the sympathovagal balance

Investigated are the responses of the average heart rate and of the balance between the 0.07-0.14 and 0.14-0.40-Hz components of the heart power spectrum to gravitational stress. This was done by taking finger blood pressure measurements in 18 young normals during two 1-hour sessions. In each session there were two supine-standing and two standing-supine transitions. For each transition the changes in average heart rate and spectral balance were computed. These changes were individually linearly related. This suggests that, for these postural transitions the spectral balance assesses the tonic autonomic balance, as well as the absolute value of the average heart rate