Added Airway Resistance and Endurance in Intensive Exercise
Technical rept. Aug-Dec 1974
EDGEWOOD ARSENAL ABERDEEN PROVING GROUND MD
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The effect of added airway resistance on endurance in running on a treadmill at 7 mph was tested in US Army male volunteers. Various combinations of inspiratory and expiratory resistance were provided by the following respiratory conditions A standard M17A1 protective mask, B modified M17 mask, C peripheral M9 mask, D M9 mask less filter, E mouthpiece and nose-clip, and F bareheaded control. In a pilot study, conditions A and F were compared at two grades on the treadmill. The decrement in endurance due to condition A was greater at the lower grade. In series 1 and 2, the six conditions were compared at a single grade for each of nine men, including duplicate tests on three of the men. The results were consistent with the hypothesis that the decrement in endurance due to added airway resistance will be small at high and low work rates and will be maximal at some intermediate work rate. The small added airway resistance commonly found in equipment for making various respiratory measurements during exercise can cause a decrement in endurance in proportion to the size of the resistance. The results raised the question of whether, in the range of resistances of modern protective masks, the expiratory resistance is more critical than the inspiratory.
- Stress Physiology