Journal of Applied Physiology, Vol 42, Issue 6 959-967, Copyright © 1977 by American Physiological Society
Dynamic and steady-state respiratory responses to bicycle exercise
D. H. Pearce and H. T. Milhorn Jr
The transient respiratory responses of 10 normal male volunteers to step
changes in work load from 0 to 300, 600, and 800 kpm/min were determined by
breath-by-breath analysis for tidal volume, minute ventilation, respiratory
frequency, end-tidal oxygen and carbon dioxide tensins, oxygen uptake,
carbon dioxide elimination, respiratory exchange ratio, and heart rate. Ten
experiments were averaged on a 5-s interval basis. Quantitative measures of
the dynamics (delay times, half-times, times to peaks, times to plateaus,
and plateau amplitudes) are presented. These parameters generally vary with
work load and reflect the speed of response of various components of the
system. Rapid ventilatory responses were seen at the initiation and
termination of exercise; however, they required up to 32.5 s for full
development. Repeated runs on three subjects at 600 kpm/min indicate that
the experiments are grossly repeatable. The data, at the initiation of
exercise, are consistent with the concept of cardiodynamic hyperpnea while
the results are not as clear-cut at the termination of exercise.
