Leg strength in peripheral arterial disease: Associations with disease severity and lower-extremity performance

Objective: The purpose of this study was to determine relationships between lower-extremity arterial obstruction, leg strength, and lower-extremity functioning. Design: The study design was cross-sectional. A total of 514 outpatients (269 with ankle-brachial index [ABI] <0.90), aged 55 and older, were identified from three Chicago-area hospitals. Individuals with history of lower-extremity revascularization were excluded. Main outcome measures: Strength in each leg, 6-minute walk, 4-meter walking velocity, accelerometer-measured physical activity, and a summary performance score were measured. The summary performance score is a composite measure of lower-extremity functioning, ranging from 0 to 12 (12 = best). The leg with the lower ABI was defined as the "index" leg, and the leg with higher ABI was defined as the "contralateral" leg. Results: Index leg ABI levels were associated linearly and significantly with strength for hip extension (P < .001), hip flexion (P < .001), knee extension (P = .066), and knee flexion (P = .003), adjusting for known and potential confounders. In adjusted analyses, the index ABI was also associated linearly and significantly with strength in the contralateral leg. Adjusting for confounders, including ABI, knee extension strength, was associated independently with functional measures. Conclusion: Among patients without prior leg revascularization, strength in each leg is highly correlated with the lower-leg ABI. Leg strength is associated independently with functional performance. Further study is needed to determine whether lower-extremity resistance training improves functioning in patients with peripheral arterial disease.