[O-HT-01-2] Home-based Daily Calf Muscle Stretching Improves Endothelial Function of Lower Limb Artery and Walking Capacity in Elderly Patients With Peripheral Artery Disease
A Randomized, Non-blinded, Crossover Study
Keywords:Muscle stretching, Endothelial function, 6-minute walking test
【Purpose】Patients with peripheral artery disease（PAD）frequently have reduced walking capacity due to insufficient oxygen supply to skeletal muscle. Our preliminary results in a rat model of aging indicate that a program of daily calf muscle stretching improves endothelium-dependent dilation of soleus muscle arterioles and increases soleus muscle blood flow during exercise；however, little is available for the effects of muscle stretching on the function of arteries supplying the legs of PAD patients. We hypothesized that home-based daily calf muscle stretching improves endothelial function of popliteal artery and walking capacity in PAD patients.
【Methods】A randomized, non-blinded, crossover study was performed to test our hypothesis. Four weeks of muscle stretching（30 min/d, 5 days/wk）and 4 weeks of usual lifestyle（no stretching）were performed in random order. Thirteen patients with PAD participated in this study（71±2 years old；7 males and 6 females）. During the stretching intervention both ankle joints were maintained at 15o of dorsiflexion using ankle dorsiflexion splints to stretch their calf muscles at home. Flow-mediated dilation（FMD；vascular endothelial function）and nitroglycerin-induced dilation（vascular smooth muscle function）of popliteal artery were measured after muscle stretching and no stretching period using ultrasound. A six-minute walk test was also performed to obtain walking distance covered during the 6 minutes（6MD）.
【Results】FMD and 6MD significantly improved after 4 weeks of muscle stretching than those measured after 4 weeks of no stretching（P＜0.01, respectively）. No difference in nitroglycerin-induced dilation was found between groups（P=0.54）. Percentage change of 6MD（%change =［（stretching-no stretching）/no stretching］x100）positively correlated with the %change of FMD（P＜0.05）.
【Discussion】These results indicate that daily calf muscle stretching enhances endothelial function of popliteal artery, resulting in improvement of walking capacity in elderly PAD patients.
【Methods】A randomized, non-blinded, crossover study was performed to test our hypothesis. Four weeks of muscle stretching（30 min/d, 5 days/wk）and 4 weeks of usual lifestyle（no stretching）were performed in random order. Thirteen patients with PAD participated in this study（71±2 years old；7 males and 6 females）. During the stretching intervention both ankle joints were maintained at 15o of dorsiflexion using ankle dorsiflexion splints to stretch their calf muscles at home. Flow-mediated dilation（FMD；vascular endothelial function）and nitroglycerin-induced dilation（vascular smooth muscle function）of popliteal artery were measured after muscle stretching and no stretching period using ultrasound. A six-minute walk test was also performed to obtain walking distance covered during the 6 minutes（6MD）.
【Results】FMD and 6MD significantly improved after 4 weeks of muscle stretching than those measured after 4 weeks of no stretching（P＜0.01, respectively）. No difference in nitroglycerin-induced dilation was found between groups（P=0.54）. Percentage change of 6MD（%change =［（stretching-no stretching）/no stretching］x100）positively correlated with the %change of FMD（P＜0.05）.
【Discussion】These results indicate that daily calf muscle stretching enhances endothelial function of popliteal artery, resulting in improvement of walking capacity in elderly PAD patients.