Response of Pulmonary Artery Pressure and Total Pulmonary Resistance of Untrained, Convalescent Man to Prolonged Mild Steady State Exercise1

Abstract

The effect of mild, steady state exercise (850 footpounds per minute) was investigated in 12 subjects free of cardio-pulmonary disease during a continuous period of 39 minutes, in the supine position, employing a bicycle ergometer. A reproducible response pattern of the pulmonary artery pressure was defined, involving an initial rise in pressure followed by a gradual decrease over the entire period of exercise. The pulmonary total resistance likewise decreased steadily throughtout the exercise period, this change being unrelated to the cardiac output. It is suggested (in conformity with the findings of others) that exercise "steady state" may be achieved and maintained relevant to total body O2 uptake and cardiac output. This is not true for the pulmonary artery pressure and total pulmonary resistance.