Gait alterations associated with walking impairment in people with peripheral arterial disease with and without intermittent claudication

OBJECTIVES: To describe gait alterations associated with impaired walking e ndurance in patients with and without lower-extremity peripheral arterial d isease (PAD) and determine whether the Caltrac accelerometer provides a val id measure of physical activity in PAD. DESIGN: Cross-sectional. SETTING: Academic medical center. PARTICIPANTS: PAD (n = 40) and non-PAD patients (n = 22) from two Chicago h ospitals. MEASUREMENTS: Participants underwent measurement of the ankle brachial inde x (ABI), leg length, and 6-minure walk. Steps per minute and step length we re measured during the first and last 100 feet of the 6-minute walk. Partic ipants wore a Caltrac accelerometer, sensitive to vertical acceleration, du ring the 6-minute walk and for 7 continuous days. RESULTS: Five PAD participants (13%) and one non-PAD participant (5%) cease d walking before the end of 6 minutes. Among the remaining participants, di stance walked in 6 minutes was more highly related to walking velocity duri ng the last 100 feet of the walk than walking velocity during the first 100 feet. ABI was associated significantly with cadence (20.77 steps/minute pe r unit ASI, P < .001) but not step length (10.12 centimeters/unit ABI, P < .08). ABI was associated significantly with 6-minute walk distance (493 fee t/unit ABI, P = .018), but this association disappeared completely after ad justment for step length and cadence. We found no difference in acceleromet er scores between PAD and non-PAD participants over a fixed distance of 800 feet (7.34 vs 7.17 activity units, P = .789). However, scores were signifi cantly different after 7 days (730.8 vs 1,485.0 activity units, P = .003). CONCLUSION: Walking performance in PAD patients who completed 6 minutes of walking was largely determined by a decline in walking velocity rather than slower initial walking velocity. ABI was more closely associated with cade nce than step length. Future studies should assess the effect of exercise p rograms and revascularization on cadence and step length in PAD.