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.