SUPERIORITY OF TREADMILL WALKING EXERCISE VERSUS STRENGTH TRAINING FOR PATIENTS WITH PERIPHERAL ARTERIAL-DISEASE - IMPLICATIONS FOR THE MECHANISM OF THE TRAINING RESPONSE

Background In patients with intermittent claudication, a supervised wa lking exercise program increases peak exercise performance and communi ty-based functional status. Patients with peripheral arterial disease also have muscle weakness in the affected extremity that may contribut e to the walking impairment. However, the potential benefits of traini ng modalities other than walking exercise, such as strength training, have not been critically evaluated in this patient population. The pre sent study tested the hypothesis that a strength training program woul d be as effective as treadmill walking exercise and that combinations of strengthening and walking exercise would be more effective than eit her alone in improving exercise performance. Methods and Results Twent y-nine patients with disabling claudication were randomized to 12 week s of supervised walking exercise on a treadmill (3 h/wk at a work inte nsity sufficient to produce claudication), strength training (3 h/wk o f resistive training of five muscle groups of each leg), or a nonexerc ising control group. Graded treadmill testing was performed to maximal ly tolerated claudication pain to define changes in peak exercise perf ormance. After 12 weeks, patients in the treadmill training program ha d a 74+/-58% increase in peak walking time as well as improvements in peak oxygen consumption (VO2) and the onset of claudication pain. Pati ents in the strength-trained group had a 36+/-48% increase in peak wal king time but no change in peak iio, or claudication onset time. Contr ol subjects had no changes in any of these measures over the 12-week p eriod. After the first 12 weeks, patients in the initial walking exerc ise group continued for 12 more weeks of supervised treadmill training . This resulted in an additional 49+/-53% increase in peak walking tim e (total of 128+/-99% increase over the 24 weeks). After the initial 1 2 weeks, patients in the strength-trained group began 12 weeks of supe rvised treadmill training, and patients in the control group participa ted in a 12-week combined program of strengthening and treadmill walki ng exercise. The combined strength and treadmill training program and treadmill training after 12 weeks of strength training resulted in inc reases in peak exercise performance similar to those observed with 12 weeks of treadmill training alone. Conclusions A supervised treadmill walking exercise program is an effective means to improve exercise per formance in patients with intermittent claudication, with continued im provement over 24 weeks of training. In contrast, 12 weeks of strength ;training was less effective than 12 weeks of supervised treadmill wal king exercise. Finally, strength training, whether sequential or conco mitant, did not augment the response to a walking exercise program.