Cardiac adaptations to training: relevance to angina pectoris

Exercise training has for many years been suggested as a useful adjunct to medical therapy for patients with ischaemic heart disease. While its popularity amongst the general public continues to grow, limitations in our ability to assess its effects on the heart have meant that, as cardiologists, our desire to encourage this popular upsurge in physical activity has been tempered by our inability to provide convincing evidence of its value to our patients. In particular the role of exercise in the rehabilitation of patients with angina pectoris is as yet unclear. This review addresses this question and states what has been proven to date and also the questions which remain to be answered. It also suggests some reasons why we have failed to provide answers so far, and ways in which new technology may be used in the future. Studies in animals, asymptomatic humans, and patients with ischaemic heart disease have demonstrated that training reduces the resting heart rate and double product of heart rate times blood pressure at any given level of exercise. This has the benefit of reducing myocardial oxygen consumption during exercise. There is also evidence that it increases end-diastolic volume and left ventricular wall thickness. Evidence for an increase in maximal myocardial oxygen consumption in angina is limited to one or two studies showing an improved maximum double product and to the occasional patient proven by echocardiography or nuclear studies to increase ejection fraction by training. Better selection of patients and use of new imaging techniques should provide further information in the near future.