Journal of Applied Physiology, Vol 41, Issue 5 790-796, Copyright © 1976 by American Physiological Society
System analysis of heart rate control in man
I. Sato, Y. Hasegawa and K. Hotta
The dynamic property of the heart rate response to exercise was determined
and expressed in the frequency domain to establish a method of examining
cardiovascular control function. The response of heart rate to a stimulus
was measured at 5-s intervals in nine healthy young volunteers. The
stimulus consisted of several runs of two-step exercise practiced in
semirandom sequence for 19 min. The weight function of the system was
estimated from autocorrelation function of the input signal and
cross-correlation function between the input and output signals. The weight
function was transformed into a transfer function and its Bode plot diagram
was drawn. From the diagram, four dynamic parameters were determined. These
parameters are as follows: K is a constant showing the theoretical
steady-state increment of heart rate, and T1, T2, T3 are time constants.
The values obtained in the present experiment with the healthy young males
were: K 46.0 +/- 14.6 beats, T1, 2.12 +/- 0.44, T2, 1.12 +/- 0.16, and T3
0.70 +/- 0.07 min.
