Exercise prescription for peripheral artery disease
This is an excerpt from Clinical Exercise Physiology 4th Edition With Web Resource by Jonathan Ehrman,Paul Gordon,Paul Visich & Steven Keteyian.
Walking exercise is particularly beneficial for helping PAD patients with claudication to improve their walking ability, although all types of exercise are beneficial for general cardiovascular health. A walking exercise program causes physiological adaptations leading to higher O2, increased walking time, and enhanced quality of life. Peripheral artery disease patients with claudication are often not able to walk very well when they begin an exercise program, and their exercise prescription is set according to their individual limitations.
Patients should begin with a warm-up and end with a cool-down. Bouts of exercise are intermittent, with the length of time for each bout limited by the onset of moderate claudication (3 or 4 on the Claudication Symptom Rating Scale). Each bout is followed by a rest period to allow the leg pain to subside. These exercise and rest sessions are repeated for 35 to 50 min, at least three times a week, for a total duration of 3 to 6 mo, although some programs have been carried out for up to a year.
Initially, the prescription for exercise is to walk at the speed and grade that elicits claudication. Patients walk until they reach a 3 or 4 (moderate pain) on the Claudication Symptom Rating Scale. They then sit and rest until the pain abates. For the first few sessions, the goal is for the patient to walk and rest for a total of 35 min (with the time from all bouts added together). Walking bouts typically become longer with further training until the walking goal of 50 min per session has been reached. For patients who have received endovascular therapy or bypass surgery and may have other factors limiting exercise (e.g., orthopedic limitations or muscular fatigue), rating of perceived exertion (RPE) using the Borg 15-category scale or other walking perceived exertion scales (e.g., OMNI Walk/Run Scale) can be used to regulate exercise intensity at a moderately hard level, as has been done in the past for exercise training in asymptomatic PAD patients. Exercise intensity based on age-predicted exercise heart rate responses rather than claudication symptoms is not recommended for PAD patients.
Patients may exercise in a supervised setting or an unsupervised home or community exercise program. Supervised exercise programs have shown a greater walking distance improvement, approximately 180 m, over unsupervised exercise training. Additionally, several recent trials have shown lasting benefits on PAD patients' walking performance, even after completion of the defined supervised training period. However, supervised exercise training is often not possible because of barriers such as time constraints and habitual sedentary behavior of patients. Proximity to clinics, the need for patients to navigate large health care facilities, and transportation are also significant impediments to the successful adoption and adherence to supervised exercise.
Until recently, unsupervised exercise programs have primarily involved instructing patients to exercise at home or in the community, with relatively little follow-up. As a result, home-based programs have not, for the most part, been successful. Factors resulting in the failure of many of these programs may include a less resource-intensive approach, a lack of motivation in patients, and reliance on patient self-monitoring with no feedback. Kakkos and colleagues randomized patients with claudication into supervised and unsupervised exercise training programs and examined resulting claudication onset and peak walking times (baseline, 6 wk, and 6 mo). Patients in the home exercise program were advised to exercise daily by walking, without further advice. The supervised exercise training group improved both claudication onset time and peak walking time, versus no improvement in either outcome for patients in the home training group. Other studies have demonstrated similarly poor results after patients were instructed to exercise at home or in the community with no feedback.
However, a number of community-based exercise programs have provided more focused and intensive approaches to improve health outcomes of PAD patients. Briefly, McDermott and colleagues conducted a 6 mo randomized controlled group - based exercise program for PAD patients at an indoor community facility (e.g., track), led by a trained exercise facilitator. The program applied a group-mediated cognitive behavioral approach. Patients met with other PAD patients once weekly and completed 45 min of walking exercise and 45 min of facilitator-led discussions on various topics (e.g., benefits of walking for PAD, setting goals, monitoring exercise). The control group of PAD patients received health education sessions each week but did not receive any exercise intervention or feedback from staff regarding physical activity. Significant differences were found for 6 min peak walking distance change scores (primary outcome) between the intervention and control groups (+42.4 vs. -11.1 m [95% CI difference scores, 33.2 to 73.8] p < 0.001) at follow-up. Additionally, at 1 yr follow-up where patients were contacted by phone (biweekly for months 7-9 and once per month for months 10-12), those patients in the intervention group were able to maintain their improvements in walking performance. Thus, developing such programs with elements of supervision that occur in community settings may improve compliance and are likely to be highly beneficial.
Strength training alone, treadmill walking alone, and combinations of the two were examined in patients with claudication to determine whether one modality of training was superior. Patients with symptomatic PAD showed improvements in peak walking times with treadmill exercise or with weight training for skeletal muscles of the legs. The treadmill group, however, showed improvement in O2peak, but no changes were observed in O2peak or claudication onset time for those participating in weight training alone. More recent studies have demonstrated improvements in walking and functional outcomes following muscular strength and endurance training in patients with claudication. However, while strength training is important, it should be only complementary to the PAD patient's exercise program, as walking is still preferred because of the beneficial effects on the cardiovascular system. Other exercise modalities that have been evaluated for use in treating PAD include cycle exercise, arm ergometry, active pedal plantar flexion, and pole striding. In particular, recent evidence indicates arm ergometry may be a valid alternative for treating PAD patients and may have merit for use in patients with CLI. Table 16.9 presents a brief review of the optimal training modalities for improving various health and fitness components of PAD patients.
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