Journal of Applied Physiology, Vol 56, Issue 1 175-181, Copyright © 1984 by American Physiological Society
Effect of mechanical loading on breathing patterns in women
K. Axen, F. Haas, D. Gaudino and S. S. Haas
First-breath ventilatory responses to graded inspiratory elastic and
resistive loads were obtained from 80 women unfamiliar with respiratory
experimentation. For each load 1) responses from different subjects ranged
from a weak tidal volume defense coupled with an increased breathing
frequency to a strong tidal volume defense coupled with a decreased
frequency; 2) strong tidal volume defenders employed longer inspirations
than did weak tidal volume defenders; and 3) individual respiratory
frequency responses were mediated by changes in inspiratory and/or
expiratory timing. Thus the group response was qualitatively the same as
that reported for 80 men. Quantitatively, however, mean inspiratory airflow
responses of women exceeded those of men by an amount attributable to
women's higher intrinsic respiratory elastance. Tidal volume responses, on
the other hand, did not differ significantly, suggesting that men and women
produce different neural adjustments to loads. In support of this
hypothesis, analysis of respiratory timing responses revealed that 1) men
actively prolonged inspiration more than women during resistive loading;
and 2) women actively shortened inspiration more than men during elastic
loading. These findings indicate that the load-compensating behavior
exhibited by men and women is similar but not identical.
