Associations between lower extremity ischemia, upper and lower extremity strength, and functional impairment with peripheral arterial disease

OBJECTIVES: To identify associations between lower extremity ischemia and leg strength, leg power, and hand grip in persons with and without lower extremity peripheral arterial disease (PAD). To determine whether poorer strength may mediate poorer lower extremity performance in persons with lower arterial brachial index (ABI) levels. DESIGN: Cross-sectional. SETTING: Academic medical centers. PARTICIPANTS: Four hundred twenty-four persons with PAD and 271 without PAD. MEASUREMENTS: Isometric knee extension and plantarflexion strength and handgrip strength were measured using a computer-linked strength chair. Knee extension power was measured using the Nottingham leg rig. ABI, 6-minute walk, and usual and fastest 4-m walking velocity were measured. Results were adjusted for potential confounders. RESULTS: Lower ABI values were associated with lower plantarflexion strength (P trend=.04) and lower knee extension power (P trend <.001). There were no significant associations between ABI and handgrip or knee extension isometric strength. Significant associations between ABI and measures of lower extremity performance were attenuated after additional adjustment for measures of strength. CONCLUSION: These results are consistent with the hypothesis that lower extremity ischemia impairs strength specifically in distal lower extremity muscles. Associations between lower extremity ischemia and impaired lower extremity strength may mediate associations between lower ABI values and greater functional impairment.