The energetics of restrictive breathing
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Date
1995
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Abstract
Chest wall restriction, whether caused by disease or mechanical contraints [sic] such as protective outerwear, can cause severe decrements in pulmonary function and exercise capacity; however, thus far the study of the energy cost associated with mechanical chest restriction has been purely qualitative. The purpose of this experiment was to measure the energy cost of varied levels of external chest wall restriction. Oxygen uptake and electromyogram (EMG) measurements were recorded during chest restriction in 10 healthy males. Subjects rested for 9 minutes before hyperventilating for 6 minutes. Subjects breathed at 30, 60, and 90 liters - min- I with chest wall loads of 0, 25, 50, and 75 mmHg applied using an inflatable cushion in an immovable shell. Frequency of breathing was set at 15, 30, and 45 breaths per minute with a tidal volume (VT) of 2 liters. Oxygen uptake was measured continuously throughout the hyperventilation bouts, while controlling Vl and VT. EMG from the 3rd intercostal space was recorded twice during each minute of rest and hyperventilation. Two-way ANOVA with repeated measures revealed that chest wall loading significantly increased V02 values (P<.0001). Two-way ANOVA with repeated measures also revealed that chest wall loading significantly increased integrated EMG results (P=.0058). These data suggest that there is a significant and quantifiable increase in the energy cost associated with external chest wall restriction that is related to the level of increased work. EMG results also indicate a general pattern of increased intercostal muscle activation with external chest wall restriction, but do not support the idea that there is a threshold level of work at which the external inter-costals suddenly increase their activity.
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Vita.
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Major kinesiology