An assessment of cardiorespiratory adjustments of asthmatic adults to exercise.

The cardiorespiratory adjustments of asthmatic adults to submaximal and maximal workloads were investigated. Cardiorespiratory variables were measured every 2 min during exercise and at the end of maximal physical effort. Exercise-induced asthma (EIA) occurred in all asthmatic subjects while normal subjects maintained normal spirometry. The results suggest that asthmatic adults have no cardiac reserve or oxygen delivery limitations. They work under less efficient ventilatory conditions at submaximal workloads and have a significantly lower functional work capacity. The high degree of correlation between preexercise maximal midexpiratory flow rate (MMF) and maximum O2 consumption (max Vo2) suggests that the smaller airways contribute significantly to the observed abnormalities. We recommend that evaluation of antiasthmatic medications in exercise-induced asthma should take into consideration their effect upon smaller airways and cardiorespiratory variables.