Results:

The most recent AHA/American College of Cardiology Guideline on the Management of Patients With Lower Extremity PAD includes four recommendations supporting exercise therapy. PAD affects over 8.5 million individuals in the United States, including approximately 7% of people ≥40 years old. In patients without previous lower extremity revascularization, clinical evidence of PAD includes typical limb symptoms with exercise and an ankle-brachial index (ABI) ≤0.90, although functional impairment and decline also occur in people with asymptomatic PAD.

Patients with PAD have both structural and pathophysiologic abnormalities of calf skeletal muscle, including increased fat content, impaired mitochondrial function, inflammation, endothelial activation, apoptosis, and muscle fiber type switching. PAD is also associated with increased prevalence of neuropathy, adverse cardiovascular events, and adverse limb events. Mechanisms of training response to exercise in patients with PAD are complex and incompletely understood.

Outcome measures used for measurement of changes in walking and exercise capacity in response to exercise interventions for PAD include treadmill walking performance, the 6-minute walk test (6MWT), and subjective measures of health-related quality of life (HRQL). Treadmill peak walking time (PWT), claudication onset time (COT), peak walking distance (PWD), and claudication onset distance (COD) are the most commonly used measures of change in walking performance. Learning and placebo effects are limitations of treadmill exercise as a research outcome; advantages of the 6MWT include avoiding the need for specialized equipment and training.

Subjective measures of functional status and HRQL include PAD-specific and generalized measures. Widely used PAD-specific measures include the Walking Impairment Questionnaire (WIQ), the Vascular Quality of Life Questionnaire (VascuQoL), the Peripheral Artery Questionnaire (PAQ), and the Impact of PAD on Quality of Life questionnaire. General HRQL measures include the Short Form (SF)-36 or SF-12, and the EuroQol-5D. Questionnaire measures do not always improve after exercise therapy, even among patients with improvement in walking performance.

Components of supervised exercise therapy (SET) supported by specific evidence include: intensity, duration per session, claudication severity during walking exercise, progression of increasing volume of exercise, work-to-rest ratio, frequency, and program duration.

Study designs evaluating exercise and revascularization on functional outcomes in patients with PAD are heterogeneous, and have included comparisons between SET and revascularization, either as stand-alone interventions or in combination. Evidence generally supports positive impacts on COD and PWD with SET that are comparable to revascularization when used as a stand-alone intervention, and the greatest positive impacts have often been observed when SET and revascularization are used in combination. Durability of SET and revascularization impacts on clinical outcomes has not been consistently observed, however, and HRQL outcomes have not been consistently associated with walking outcomes.

A significant proportion of patients with PAD are asymptomatic, but no adequately powered randomized clinical trials have been conducted to assess whether exercise interventions improve walking performance in this subgroup.

Structured home-based exercise programs may be more accessible and acceptable than SET to patients with PAD. Studies demonstrating improvement with home-based exercise interventions have generally included interventions extending beyond walking advice alone, including scheduled meetings with study investigators or participant groups, telephone calls, or coaching.

Alternative walking strategies for patients with PAD that have demonstrated some efficacy include pain-free walking exercise training, leg-cycling, aerobic arm exercise training, and resistance training.

Areas in need of further research include determination of optimal exercise training methods, clinical or demographic characteristics that influence responses to exercise training and/or facilitate individualized approaches, and strategies to translate research findings into effectiveness within clinical practice.