The effect of exercise intensity on the response to exercise rehabilitation in patients with intermittent claudication

PURPOSE: The purpose of this randomized trial was to compare the efficacy of a low-intensity exercise rehabilitation program vs a high-intensity program in changing physical function, peripheral circulation, and health-related quality of life in peripheral arterial disease (PAD) patients limited by intermittent claudication. METHODS: Thirty-one patients randomized to low-intensity exercise rehabilitation and 33 patients randomized to high-intensity exercise rehabilitation completed the study. The 6-month exercise rehabilitation programs consisted of intermittent treadmill walking to near maximal claudication pain 3 days per week at either 40% (low-intensity group) or 80% (high-intensity group) of maximal exercise capacity. Total work performed in the two training regimens was similar by having the patients in the low-intensity group exercise for a longer duration than patients in the high-intensity group. Measurements of physical function, peripheral circulation, and health-related quality of life were obtained on each patient before and after the rehabilitation programs. RESULTS: After the exercise rehabilitation programs, patients in the two groups had similar improvements in these measures. Initial claudication distance increased by 109% in the low-intensity group (P < .01) and by 109% in the high-intensity group (P < .01), and absolute claudication distance increased by 61% (P < 0.01) and 63% (P < .01) in the low-intensity and high-intensity groups, respectively. Furthermore, both exercise programs elicited improvements (P < .05) in peak oxygen uptake, ischemic window, and health-related quality of life. CONCLUSION: The efficacy of low-intensity exercise rehabilitation is similar to high-intensity rehabilitation in improving markers of functional independence in PAD patients limited by intermittent claudication, provided that a few additional minutes of walking is accomplished to elicit a similar volume of exercise.