Radiotelemetric Cardiorespiratory Determinations During Submaximal Dynamic Exercise

Abstract

Under normal conditions, healthy people at submaximal exercise show a close correlation between work load and cardiac output (i.e. oxygen uptake versus heart rate, respectively). Subjects with chronic bronchospastic disease respond to specific bronchodilators(e.g. isoproterenol) with increases in heart rate -- even without exercise. New bronchodilators (salbutamol) which do not exert such an influence on the heart rate are being studied for their effect on "exercise induced asthma." Measurements of airway resistance(R(A)) and thoracic gas volume (V(tg)) during dynamic exercise (treadmill) pose complex instrumentation problems. The radiotelemetric determinations of specific airway conductance (G(A)/V(tg) where G(A) = 1/R(A)) now appear practicable. The acquisition of such data in conjunction with other radiotelemetered measurements (heart rate from R-R interval) indicate that patients with chronic bronchspastic disease, when treated with bronchodilators, may tolerate physical exercise more safely.