Alt. Uusitalo et al., NONINVASIVE EVALUATION OF SYMPATHOVAGAL BALANCE IN ATHLETES BY TIME AND FREQUENCY-DOMAIN ANALYSES OF HEART-RATE AND BLOOD-PRESSURE VARIABILITY, Clinical physiology, 16(6), 1996, pp. 575-588
We examined how the time and frequency domain measures of heart rate a
nd blood pressure variability at supine rest reflect the sympathovagal
balance of 23 female and male endurance athletes. Pharmacological blo
cking by atropine and propranolol was used as a standard for defining
autonomic control of the heart. The Rosenblueth and Simeone model for
neural control of heart rate was used to calculate the sympathovagal b
alance index (A(bal)) Atropinization significantly decreased all time
and frequency domain measures of heart rate and blood pressure variabi
lity. P-Blockade significantly decreased further the low- (<0.07 Hz) a
nd medium-frequency power (0.07-0.15 Hz) variability of R-R intervals
(RRI) and SD of RRI. A(bal) was 0.629 +/- 0.019, indicating that paras
ympathetic activity predominated in the athletes. Basal heart rate (r
= 0.519, P < 0.01), SD of RRI (r = -0.533, P < 0.01), root-mean-square
of successive RRIs (RRI RMSSD) (r= -0.579, P < 0.05), RRI total (r= -
0.557, P < 0.01) and RRI high-frequency (HF) power (r= -0.582, P < 0.0
1) correlated significantly with A(bal) and parasympathetic activity i
ndex. We concluded that the best non-invasive method of evaluating the
sympathovagal balance of athletes at supine rest is to measure SD of
RRI, RRI RMSSD, HF and total power of RRI variability. All heart rate
variability measures were mainly parasympathetically modulated. The na
ture of blood pressure variability measures remained unclear and they
could not be used to evaluate the sympathovagal balance among athletes
.