Exercise testing protocols and training regimens are well established for patients recovering from myocardial infarction or coronary artery bypass surgery. However, exercise rehabilitation programs for patients with peripheral arterial disease or left ventricular dysfunction with congestive heart failure have not been well developed. Several recent reports have established reproducible exercise testing protocols with objective measures of performance for patients with peripheral arterial disease and congestive heart failure. Using these testing methods to define changes in exercise capacity, exercise training programs have been shown to result in a significant increase in exercise performance and community-based quality of life. The mechanism of improvement appears to involve peripheral adaptations in skeletal muscle metabolism rather than increases in cardiac output or peripheral blood flow.