Randomized controlled trial of supervised exercise to evaluate changes in cardiac function in patients with peripheral atherosclerotic disease

INTRODUCTION: Peripheral atherosclerotic disease (PAD) is a condition characterized by low functional capacity which is associated with impaired free living, ambulation and low exercise tolerance. The purpose of this randomized controlled study was to evaluate whether changes in maximal walking time are associated with adaptations in cardiovascular function following supervised exercise. METHODS: After ethics approval, 28 patients (63 +/- 11 years) completed a graded treadmill test (2 min stages, 3.2 km h(-1), with gradient increasing 2% every 2 min) until they reached level three or four on the claudication pain scale. Peak oxygen consumption was assessed on a breath-by-breath basis, by online expiratory gas analysis. Following a 40-min recovery period, peak cardiac output was measured using the non-invasive carbon dioxide rebreathing method described by Defares (J Appl Physiol, 13, 1958, 159). Peak cardiac power output was then computed using the equation described by Cooke et al. (Heart, 1998, 79, 289). Patients were randomly assigned to one of two groups: supervised, who exercised at the hospital twice weekly for 12 weeks or control, who received normal treatment which included encouragement to walk regularly. RESULTS: After 12 weeks, there were no significant changes in body mass, peak oxygen consumption, peak cardiac output, peak heart rate, peak cardiac power output, respiratory exchange ratio or rating of perceived exertion in both the supervised and control group. There was a significant improvement (91%) in maximal walking distance following the supervised exercise programme. Although patients' peak cardiovascular measurements were unchanged, the patients in the supervised exercise group were able to complete a higher workload at the end of the 12 weeks of exercise, for the equivalent demands on the circulation system. CONCLUSIONS: The findings from this study suggest that a short-term period of supervised exercise training results in an improved walking time in patients with limiting claudication because of PAD. It also demonstrated that the cardiovascular system becomes more efficient in meeting the demands of exercise. It is recommended that individuals with PAD should undertake exercise as a form of treatment.