NORMAL RESPIRATORY AND CIRCULATORY PATHWAYS OF ADAPTATION IN EXERCISE 1

Abstract

Rahn and Otis (1) have described the normal changes in the alveolar gases during work and demonstrated the quantitative relationships be- tween alveolar oxygen, carbon dioxide, respiratory quotient and ventilation by means of continuous recording of gas analyses. They were able to delineate the pathways of change which are con- trolled by the excretion of carbon dioxide, and ob- serve the effects of hyperpnea, hypoxia, hypoventilation and CO2 breathing as well. Pelnar (2), at first independently and later in conjunc- tion with Rahn, observed the changes in expired air composition in normal subjects as well as in patients with cardiorespiratory impairment in rela- tion to work. By means of a simple diagram re- lating the changes in 02 and CO2 content of ex- pired air with the respiratory quotient during the stress of exercise, he felt that he could delineate respiratory function better than by any other means in a manner that paralleled the intensity of dyspnea in patients. Between the extremes of a) normal performance with a large circular curve and b) the abnormal performance with no change in these values during exercise, Pelnar found a series of results which were characteristic of the varied stages of dyspnea. Thus he was able to evaluate functional performance largely in terms of changes in the respiratory gases during exercise. In con- trast to this are the older methods reported by Kaltreider and McCann (3) who relied chiefly on ventilation volumes and ventilation indices to ap- praise pulmonary capacity during work.