Effects of ‘Cool-Down’ During Exercise Recovery on Cardiopulmonary Systems in Patients With Coronary Artery Disease

Abstract

The effects of ‘cool-down’ during exercise recovery on cardiovascular and respiratory systems have not been fully clarified. The recovery of respiratory gasses was compared in cardiac patients after maximal exercise during which subjects either performed a cool-down or rested. Twenty-one patients (61±10 years) with coronary artery disease performed 2 symptom-limited incremental exercise tests on a cycle ergometer: one with a cool-down and the other without during recovery from the maximal exercise test. Expired gasses were analyzed on a breath-by-breath basis throughout the test and for 6 min of recovery. Without a cool-down, the ventilatory equivalent for O₂ (VE/VO₂) increased dramatically during recovery compared with the resting values or those of peak exercise: 44.5±7.7 at rest, 44.0±10.6 at peak exercise and 63.3±14.5 after 2 min of recovery. End-tidal PO₂ (PetO₂) also increased significantly during recovery. However, the overshoot phenomenon of these variables was attenuated when cool-down exercise was performed during recovery. The high ratio of VE/VO₂ reflects ventilation perfusion (VA/Q) unevenness and PetO₂ is an index of arterial PO₂. Thus, it is suggested that cool-down exercise during recovery after maximal exercise testing provides beneficial effects on the respiratory system by decreasing the VA/Q unevenness and relative hyperventilation that are observed when cool-down exercise is not performed.