Corridor-based functional performance measures correlate better with physical activity during daily life than treadmill measures in persons with peripheral arterial disease

Objective: To compare associations of physical activity during daily life with treadmill walking performance and corridor-based functional performance measures in persons with lower extremity peripheral arterial disease (PAD). Study Design: Cross-sectional. Subjects: One hundred fifty-six men and women with PAD who completed baseline measurements and were randomized into the study to improve leg circulation (SILC) exercise clinical trial. Main Outcome Measures. Participants completed a Gardner-Skinner treadmill protocol. Corridor-based functional performance measures were the 6-minute walk, walking velocity over four meters at usual and fastest pace, and the short physical performance battery (SPPB) (0-12 scale, 12 = best). Physical activity during daily life was measured continuously over 7 days with a Caltrac (Muscle Dynamics Fitness Network, Inc, Torrence, Calif) accelerometer. Results. Adjusting for age, gender, and race, higher levels of physical activity during daily life were associated with greater distance achieved in the 6-minute walk (P trend = .001), faster fast-paced four-meter walking velocity (P trend < .001 faster usual-paced four-meter walking speed (P trend = .027) and a higher SPPB (P trend = .005). The association of physical activity level with maximum treadmill walking distance did not reach statistical significance (P trend = .083). There were no associations of physical activity with treadmill distance to onset of leg symptoms (P trend = .795). Conclusion: Functional performance measures arc more strongly associated with physical activity levels during daily life than treadmill walking measures. (J Vasc Surg 2008;48:1231-7.)