Circulatory adjustments to dynamic exercise and effect of physical training in normal subjects and in patients with coronary artery disease

Abstract

D URING the past decade, exercise tests and physical training programs have been used with increasing frequency in the diagnosis and management of coronary artery disease (CAD). Even though severe restrictions in physical activity were previously recommended to such patients, training studies have demonstrated that properly executed training programs effectively improve the exercise tolerance in the majority of CAD patients’ -I3 while incurring only small risks.r2*r4 Furthermore, exercise tests performed according to a suitable protocol provide valuable diagnostic information about the functional capacity of the cardiovascular system and form a rational basis for recommendations on physical activity in these patients.” Studies of the cardiovascular adjustments to exercise and training have mainly been concerned with central circulatory parameters. Prerequisite to a high level of endurance performance is a great capacity of the oxygen transport system. For example, maximal oxygen uptake has been correlated to heart volume, blood volume, and the total amount of hemoglobin.16*r7 Moreover, the cardiac stroke volume (SV) appears to be a functional circulatory parameter that most clearly separates well trained athletes from sedentary subjects.r’ The finding that SV increases in response to training 19J20 has focused attention on the importance of the heart as a pump. The opinion that improved circulatory adjustment to submaximal exercise and increased maximal aerobic capacity are both related to primary central cardiovascular adaptations has thus prevailed. Recent evidence however, suggests this cause and effect concept may not be valid, and it is now recognized that the effects of training are not limited to the central circulation.21 In this context,