The effect of dietary modification on the training outcome and body composition in patients undergoing a cardiac rehabilitation programme

The benefit of the exercise element of cardiac rehabilitation is well recognized. This study examines the influence of dietary modification during an exercise programme on changes in functional capacity in rehabilitation patients. Thirty male post coronary artery bypass graft patients were recruited. Prior to commencing a ten-week aerobic exercise programme all patients underwent a symptom limited exercise stress test (EST), body composition analysis, a fasting lipid profile and dietary assessment. Patients were assigned to one of three dietary regimens for the duration of the exercise programmes. Diets were modified in terms of carbohydrate and fat content as follows: diet A was an athletic type diet (60–65% carbohydrate, 20–25% fat), diet B was a traditional lipid-lowering diet (50–55% carbohydrate, 30% fat) and diet C was a weight-reducing lipid-lowering diet (50–55% carbohydrate, 30% fat). All baseline measurements were repeated on completion of the exercise programme. EST results for subjects who followed diet A, the high carbohydrate diet showed a significant improvement in functional capacity and duration of exercise post-training (P<0.007 and P<0.005 respectively). These improvements were achieved at a significantly lower heart rate for equal work load compared to the other two groups (P<0.005). These combined improvements were not achieved by either of the other two groups. The results of this study suggest that dietary manipulation significantly influences the outcome of exercise training in cardiac rehabilitation. The optimum diet in this patient group was a high carbohydrate, low fat, and weight-maintenance diet.