Static Muscular Stretching for Treatment of PAD

Patients with peripheral arterial disease (PAD) often have walking impairment due to insufficient oxygen supply to skeletal muscle. The investigator's pilot study in PAD patients has shown that endothelial function and walking distance improve with regular static muscle stretching. Therefore, the purpose of this study is to determine whether prescriptive muscle stretching improves muscle oxygenation and walking ability in PAD patients. This is a single-blinded study in 40 patients with stable symptomatic PAD. Patients assigned to the stretch group will use ankle splints (both legs) to perform static muscle stretching for 4 weeks (ankle dorsiflexion applied 30 min/d, 5 days/wk). Patients assigned to the control group will also wear the ankle splints daily but without invoking any dorsiflexion, i.e., without stretching. Measurements will consist of ankle-brachial index (ABI) at rest and post-exercise, skeletal muscle oxygenation (evaluated with near-infrared spectroscopy (NIRS)), and 6 minute walk test (6MWT), performed at baseline and after 4 weeks of stretching (or control splint placement). In addition, NIRS will be used to evaluate muscle oxygenation while patients are wearing the splint device in order to quantitatively prescribe the angle of dorsiflexion that provides optimum stretch and deoxygenation of the calf muscles without causing pain. Primary outcomes include increased muscle oxygenation during exercise and walking distance after 4 weeks of static muscle stretching. Results from this study will be used to support funding applications for a larger efficacy trial.

Subjects assigned to this group will be instructed on how to wear the device to produce the appropriate amount of dorsiflexion (stretch). Splint devices will be worn at the assigned angle 5 days/week, 30 minutes/day, for 4 weeks. ABI, muscle oxygenation, and walking distance will be assessed pre/post stretching. Other health surveys will be administered.

Subjects assigned to this group will wear the splints but instructed to wear the device in a position that produces no stretch. Splint devices will be worn at the assigned angle 5 days/week, 30 minutes/day, for 4 weeks. ABI, muscle oxygenation, and walking distance will be assessed pre/post stretching. Other health surveys will be administered.

Ankle splint will be slightly modified from the commercial form to include a pneumatic air cell secured under the forefoot below the splint's padded lining. This replaces the foam wedge provided by the manufacturer, allowing a gradual adjustment of the forefoot/toe region.

Inclusion Criteria: Age 40+ A resting ankle-brachial index (ABI) of 0.90 or less in either leg Stable disease (PAD) for a minimum of 3-months Exclusion Criteria: Habitual exercise (30 minutes of continuous activity for 3 or more days per week) Cardiovascular rehabilitation program during the past 3 months Below or above-knee amputation, critical limb ischemia (ulceration or gangrene) Leg pain at rest Cardiorespiratory disease Diabetes Major surgery or lower extremity revascularization during the previous 3 months Major medical illness treatment during the prior 12 months Central neurological disease Limited ankle or knee joint range of motion Requirement of oxygen with activity or exercise More than a class II New York Heart Association level of heart failure Wheelchair confinement, or inability to walk Cognitive disorder Vasculitis problem including Takayasu's arteritis, Buerger's disease, collagen disease or Raynaud's disease