Abstract Body (Do not enter title and authors here): Purposes. We determined whether patients with peripheral artery disease (PAD) who walked at least 7,000 steps/day had better microvascular function, assessed by calf muscle oxygen saturation (StO₂), and more favorable vascular biomarkers than patients who walked less than 7,000 steps/day. A secondary aim was to determine whether group differences in calf muscle StO₂ and vascular biomarkers persisted after adjusting for severity of PAD, and demographic and clinical characteristics.
Methods. Five hundred and sixteen patients were assessed on daily ambulatory activity for one week with a step activity monitor, and were grouped according to whether they walked fewer than 7,000 steps/day (Group 1; n=306) or for 7,000 steps/day or greater (Group 2; n=210). Patients performed a standardized Gardner-Skinner graded treadmill test, and calf muscle StO₂ was continuously measured over the medial gastrocnemius muscle of the more symptomatic leg using near-infrared spectrometry. Additionally, patients had blood samples drawn for measurement of high-sensitivity C-reactive protein (HsCRP).
Results. Exercise time to reach the minimum calf muscle StO₂ was significantly longer (p=0.025) in Group 2 (297±339 sec) than in Group 1 (210±232 sec). Additionally, HsCRP was significantly lower (p<0.001) in Group 2 (4.0±4.5 mg/L) than in Group 1 (6.8±10.7 mg/L). In multivariable linear regression models, exercise time to minimum calf muscle StO₂ was significantly associated with physical activity group status after adjusting for ankle/brachial index (Model 1) (p=0.032), and after adjusting for age, race, sex, education, and body mass index (Model 2) (p=0.044). HsCRP was significantly associated with physical activity group status after adjusting for Model 1 (p<0.001), Model 2 (p<0.001), and the two models combined (Model 3) (p<0.001).
Conclusions. Walking at least 7,000 steps/day was associated with better microvascular function in the calf muscle during exercise and with lower vascular inflammation in patients with symptomatic PAD. The clinical significance is that community-based walking for at least 7,000 steps/day is a simple goal that is associated with more favorable vascular outcomes in patients with symptomatic PAD.