SummaryPhysical effort induces important adaptation of respiratory and circulatory processes. The author reviews the different means of testing them. The increase of pulmonary ventilation may be important and differently related, to the oxygen consumption than during rest. The increase of the oxygen utilization coefficient is a constant fact in normal subjects during moderate effort. The«oxygen debt»induced by exercice is always present, but its importance is variable according to individuals.Alveolar ventilation and perfusion adapt themselves perfectly to effort and under physiological conditions, the deficit of blood saturation in oxygen, remains very slight.Catheterization of the heart allows a precise study of the circulatory conditions in the lungs. Physiological observations are very few, but nevertheless enable us to value the relations between cardiac output and the pressure observed in pulmonary artery. Furthermore, they bring into light adaptability of the pulmonary circulation.