Comparative Effects of Aging and Coronary Heart Disease on Submaximal and Maximal Exercise

The relative contributions of aging and coronary heart disease to the impairment of functional capacity were assessed in 117 coronary patients, 117 age-matched healthy middle-aged men, and 62 healthy young men by utilizing a multistage treadmill test of maximal exercise. With aging alone, duration of exertion and maximal exercise heart rate were diminished while maximal systolic pressure increased. The percentage of heart rate reserve from submaximal (stage 1) to maximal exercise was unaltered so that the relative heart rate stress of submaximal work on the heart was not affected. Transient postexertional S-T depression was related to increasing age and high cardiac work loads. With coronary disease, maximal duration, maximal heart rate, maximal systolic pressure, and heart rate difference (maximal heart rate during exercise minus resting heart rate just before exercise) were all reduced, while the relative heart rate stress of submaximal exercise was greater. The frequency of S-T depression was both age and disease dependent. Postexertional S-T depression of myocardial ischemia was prolonged and usually associated with angina in patients with coronary occlusive disease and subnormal performance in contrast to a more transient painless response which occurred in healthy subjects with performance which was "supernormal" in comparison with normals who exhibited no S-T depression.