Journal of Applied Physiology, Vol 42, Issue 1 28-32, Copyright © 1977 by American Physiological Society
Effects of respiratory equipment on endurance in hard work
F. W. Stemler and F. N. Craig
Men ran to a voluntary end point under the following conditions listed in
increasing order to resistance, expressed as inspiratory/expiratory in
mmH2O at a flow of 4 l-s-1: 1) bare-headed 0/0; 2) face mask 0/0; 3) face
mask -6/14; 4) mouthpiece and valves -25/29; 5) face mask -96/62; and 6)
face mask -148/60. Average endurance was 545, 490, 434, 392, 343, and 338
s, respectively. Despite the diverse features of the equipment in
conditions 2-6, there seemed to be a rather smooth relation between
resistance and endurance. There was no indication of a threshold below
which endurance would be indifferent to resistance. The duration of the
phases of the respiratory cycle was measured by means of a fine
thermocouple in the airway. The variability in the duration of the
expiratory phase at the end of the run seemed to weaken the concept that
the attainment of a critically short expiratory time might be related to
the subject's decision to halt running.
