Effects of physical training on exertional S-T-segment depression in coronary heart disease.

Abstract

Symptom-limited maximal oxygen intake (V O O2 S-L ) and electrocardiographic responses to multistage treadmill test were determined before and after 3 months of physical training in 14 patients with coronary heart disease. Six patients also had hemodynamic studies done at several submaximal work loads in the upright position before and after training. S-T-segment responses were measured by computer averaging of 100-beat samples. After physical training, the heart rate ( P < 0.01) and the product of heart rate and systolic blood pressure ( P < 0.02) at submaximal exercise were lower and attended by significantly less S-T-segment depression. At maximal exercise, however, the heart rate ( P < 0.01) and the product of heart rate and systolic blood pressure ( P < 0.02) were higher after training, and the S-T-segment depression was more pronounced ( P < 0.005). The quantitative relationships of S-T-segment depression to either exercise heart rate, product of heart rate and systolic blood pressure, or to pressure-rate product (product of heart rate and mean blood pressure) were unaffected by physical training. The V O O2 S-L increased by 20.8% ( P < 0.001); the product of heart rate and systolic blood pressure at symptom-limited exercise increased by 10% ( P < 0.005) in the angina patients, which may indicate a higher angina threshold after physical training. It is concluded that physical training of coronary patients changes S-T-segment responses to submaximal and maximal exercise: these modifications presumably result from changes in heart-rate and blood-pressure responses to exercise, rather than from an improved coronary circulation.