Improving Functioning in Peripheral Arterial Disease

BACKGROUND:

Previous work demonstrates that functional limitations associated with peripheral arterial disease (PAD) are diverse and include slower walking speed, poorer walking endurance, and impaired balance as compared to persons without PAD. Although treadmill-walking exercise improves treadmill performance in patients with intermittent claudication (IC), treadmill performance does not correlate well with community walking ability in older men and women. In older patient populations without PAD, resistance training improves functioning and walking endurance, but this mode of exercise has not been sufficiently studied in PAD. Furthermore, although 65% to 70% of men and women with PAD are either asymptomatic or have exertional leg symptoms other than IC, no prior studies have assessed the effects of exercise interventions in PAD patients who do not have IC.

DESIGN NARRATIVE:

The randomized, control study will determine whether a 6-month supervised treadmill exercise program and a supervised lower extremity progressive resistance training program, respectively, improve lower extremity functioning compared to a nutrition control group among 150 PAD patients with and without IC. The investigators hypothesize that participants in the treadmill walking exercise program and participants in the progressive resistance training program, respectively, will experience greater improvement in functional outcomes than participants in the nutrition control group. The primary functional outcome measures in descending order of importance are 6-minute walk distance and the summary performance score. The summary performance score is a composite measure of lower extremity functioning (usual walking speed, standing balance, and time required for five repeated chair rises) measured on a 0-12 scale that predicts future risk of nursing home placement, mobility loss, and mortality. The study will also identify mechanisms by which the exercise interventions improve functioning in PAD. Mechanisms to be studied include changes in blood viscosity, calf blood flow, brachial artery endothelial reactivity, and inflammatory cytokine levels. By identifying the optimal exercise program for improving functioning in PAD patients with and without IC, the findings will have substantial clinical and public health implications for millions of patients with PAD.

Inclusion criteria

• 150 peripheral arterial disease patients with and without IC

Exclusion criteria

• Below or above-knee amputation
• Wheelchair confinement
• Inability to walk on a treadmill or inability to perform progressive resistance training
• Inability to return to the medical center three times weekly for 6 months
• Walking impairment due to a cause other than PAD
• Class II New York Heart Association (NYHA) heart failure or angina (heart failure or angina occurring at rest or with minimal exertion)
• Planned lower extremity revascularization or any other major surgery within 12 months
• Any increase in anginal symptoms during the previous 6 months or angina at rest
• Subjects with silent coronary ischemia, defined as ST segment depression greater than or equal to 1 mm during baseline exercise treadmill test without associated chest discomfort, unless they have had a normal perfusion stress test during the previous 6 months
• Subjects with left-bundle branch block or significant ST-T wave changes on their baseline ECG who do not have a perfusion stress test demonstrating absence of reversible ischemia within the previous 6 months
• Lower extremity revascularization, major orthopedic surgery, or other major surgery during the previous 3 months
• Myocardial infarction or coronary artery bypass grafting during the previous 3 months
• Major medical illnesses that may interfere with subject's ability to complete the interventions and/or follow-up testing
• Current foot ulcer
• ABI greater than 0.95
• Life expectancy less than 12 months
• Does not speak English
• Patient is currently involved in another clinical trial
• Dementia
• Poorly controlled blood pressure
• Current significant exercise, defined as exercising three times weekly for 30 minutes with sufficient exertion to produce a sweat or other exercise that is comparable to the exercise interventions offered in our protocol
• Treatment for cancer (other than non-melanoma skin cancer) during the past 12 months (including radiation therapy, chemotherapy, or surgery)