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Matthew Martenson1, Judy Muller-Delp1, Jacob Caldwell2, Lawrence Kaelin3, Albert Hakaim4, Lynn Panton, FACSM1. 1Florida State University, Tallahassee, FL. 2University of Wisconsin La Crosse, La Crosse, WI. 3Vascular Surgery Associates, Tallahassee, FL. 4Mayo Clinic, Jacksonville, FL.

BACKGROUND: Peripheral Artery Disease (PAD) is a vascular disease that affects over 8 million Americans. PAD patients commonly have difficulty walking due to pain in the legs during physical exertion. Walking therapy has been recommended to improve walking performance and attenuate disease progression, but this therapy remains underutilized in PAD patients. Recent evidence indicates that muscle stretching via ankle dorsiflexion splints improves vascular health and walking performance in PAD; however, it is currently unknown how muscle stretching affects tissue oxygenation (StO2) in PAD. PURPOSE: Purpose of study was to determine the impact of 4 wks of calf muscle stretching on measures of tissue oxygenation in patients with PAD. METHODS: Thirteen PAD patients (69.3±9.4 yrs) were randomized to either a stretch (n=9) or a non-stretch group (n=4). Patients in the stretch group wore the splints for 30 min/day, 5 days/wk for 4 wks. A 5-min vascular occlusion test and a 6-min walk test (6MWT) were administered before and after the intervention. StO2 was monitored via Near-Infrared Spectroscopy (NIRS) during the vascular occlusion test and the 6MWT. Tissue oxygen uptake and microvascular reperfusion were determined from the vascular occlusion test, while relative changes in StO2 were determined at minutes 1 and 2 of the 6MWT. Change data were analyzed using paired t-tests and significance was accepted at p<0.05. RESULTS: Muscle stretching improved microvascular reperfusion following occlusion (Pre: 0.34±0.25; Post: 0.52±0.29 ΔStO2/sec). The relative increase in oxygen utilization at minute 1 (Pre: 63±25; Post: 73±23%) and minute 2 (Pre: 69±22; Post: 84±17 %) of the 6MWT was greater after 4 wks of muscle stretching. The rate of tissue oxygen uptake during occlusion tended to increase after muscle stretching (Pre: -0.10±0.03; Post: -0.12±0.04 ΔStO2/sec; p=0.06). Walking distance also tended to increase following the intervention (Pre: 330±118m; Post:351±117m; p=0.08). There were no significant changes in any of the NIRS measurements in the non-stretch group. CONCLUSIONS: These results indicate that 4 wks of muscle stretching improves microvascular reactivity and StO2 of the calf muscles during walking. This muscle stretching intervention may have value as a means of maintaining perfusion and function of the calf muscles in PAD patients with limited mobility.

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