Cardiopulmonary exercise testing before and after conditioning in older coronary patients.

Cardiac rehabilitation has been demonstrated to improve aerobic capacity in young and middle-aged coronary patients. The effect of an aerobic conditioning program on cardiopulmonary markers of fitness was assessed in 22 older patients (mean age 68 years) following a coronary event compared with 37 younger patients (mean age 52 years). Before conditioning, peak oxygen consumption was lower in the older patients, 16.9 versus 24.3 cm3/kg/min (p less than 0.001), as was exercise duration and maximal ventilation. Older coronary patients were more likely to stop exercise at a respiratory equivalent ratio of less than 1.00 (8 of 22 versus 4 of 37, p less than 0.05) and therefore often did not attain a true maximal cardiopulmonary limitation. Both groups had similar increases in peak oxygen consumption following a 36-session conditioning program, improving 27% in the older group and 23% in the younger group. Duration of treadmill exercise on a Balke treadmill protocol increased similarly in the two groups, 62% in the older group (from 8.9 to 14.3 minutes) and 40% in the younger group (from 12.2 to 17.1 minutes) (p = NS). Thus while older patients following coronary events are substantially less fit than younger patients, they obtain a similar relative improvement of aerobic capacity with a graded conditioning program.

Usefulness of myocardial ischemia as predictor of training effect in cardiac rehabilitation after acute myocardial infarction or coronary artery bypass grafting.

Exercise capacity increases to a variable degree in coronary patients during cardiac rehabilitation. The effect of baseline exercise-induced ischemia on the response to a 12-week conditioning program was evaluated in 106 coronary patients. The magnitude of exercise conditioning response was greater in nonischemic patients than in ischemic patients, with maximal exercise intensity increasing 69 versus 50% (7.2 to 12.1 vs 7.1 to 10.6 METs) (p less than 0.05) and maximal oxygen consumption increasing 28 versus 10% (23.1 to 29.6 vs 23.0 to 25.4 cc/kg/min) (p less than 0.05). Markers of conditioning during submaximal exercise such as heart rate and heart rate-systolic blood pressure product were similarly reduced in both groups. The groups did not differ by age, diagnosis, resting ejection fraction, incidence of beta-blocker use, maximal exercise capacity, maximal exercise heart rate, blood pressure or intensity of actual exercise training. These results suggest that exercise-induced ischemia alters the stimulus to adapt to exercise training.