Yoshiharu Koyama, MD; Akira Koike, MD*; Takashi Yajima, MD; Hiroshi Kano, MD; Fumiaki Marumo, MD; Michiaki Hiroe, MD

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 6min 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 (P_ET O₂) 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 P_ET O₂ 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.
(Jpn Circ J 2000; 64: 191- 196)

Key Words: Breathing control; Cool-down; Exercise recovery; Exercise test; Overshoot

Mailing address: Akira Koike, MD, Department of Critical Care Medicine, Tokyo Medical and Dental University, 5-45, Yushima 1- chome, Bunkyo-ku, Tokyo 113-8519, Japan. E-mail: koike.ccm@ med.tmd.ac.jp