Effects of Muscle Stretching on Vascular Endothelial Function in Patients With Peripheral Arterial Disease

This study is a prospective randomized, non-blinded, crossover trial conducted at Tallahassee Memorial HealthCare, Tallahassee, FL, USA between October 2015 and May 2016. The Tallahassee Memorial Healthcare Institutional Review Board and the Human Subject Committee at Florida State University approved the study prior to initiation. Informed written consent was provided by all patients prior to enrollment.

Study Patients The study sample consisted of patients with stable symptomatic PAD. Inclusion criteria included reproducible claudication with walking associated with an ankle brachial index of less than 0.90,15 and/or computed tomographic angiographic evidence of at least a 60% stenosis of the iliac, femoral, or popliteal artery deemed to be the source of claudication. Individuals with critical limb ischemia or who had severe comorbid conditions limiting their walking ability were excluded.

Study Design:

Participants were initially randomized to undergo either 4 weeks of passive stretching or 4 weeks of no stretching (control), respectively, followed by cross-over to the other intervention. Patients were evaluated at baseline, after the first 4 weeks of initial intervention (stretching or no stretching) and then again after 4wks following the cross-over intervention (stretching or no stretching). Participants were taught how to apply a simple dorsiflexion splint and during the 4 wks of daily stretching intervention and applied the splint daily at home for 30 minutes/day, 5 days/week. Endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent nitroglycerin-induced dilation (NID) of the popliteal artery (measured by doppler ultrasound) and a 6 minute walk test were evaluated at baseline and after each 4 week treatment interval.

Muscle stretching Protocol. To passively stretch each patient's calf muscle, dorsiflexion splints (Healwell Plantar Fasciitis Night Splint®, FLA Orthopedics, Charlotte, NC, USA) were applied. Using the splint, ankle joints were kept at 15 degrees of dorsiflexion for 30 min/day, 5 days/wk, for the 4 week interval. The splint has a strap to adjust the angle of the joint. Participants learned how to wear the splint correctly from a trained physical therapist who initially fitted and adjusted the splint. Splints were sent home with the patient and a physical therapist was available for questions by phone. Using the splint, both the gastrocnemius and soleus muscles were effectively stretched. If participants complained of pain during muscle stretching, the physical therapist assisted in adjusting the straps, but efforts were made to maintain the angle of dorsiflexion.