Association between daily ambulatory activity patterns and exercise performance in patients with intermittent claudication

Purpose To determine the association between daily ambulatory activity patterns and exercise performance in patients with intermittent claudication. Methods One hundred thirty-three patients limited by intermittent claudication participated in this study. Patients were assessed on their ambulatory activity patterns for 1 week with a small, lightweight step activity monitor attached to the ankle using elastic velcro straps above the lateral malleolus of the right leg. The step activity monitor recorded the number of strides taken on a minute-to-minute basis and the time spent ambulating. Patients also were characterized on ankle-brachial index (ABI), ischemic window (IW) after a treadmill test, as well as initial claudication distance (ICD), and absolute claudication distance (ACD) during treadmill exercise. Results The patient characteristics (mean ± SD) were as follows: ABI = 0.71 ± 0.23, IW = 0.54 ± 0.72 mm Hg · min · meter−1 , ICD = 236 ± 198 meters, and ACD = 424 ± 285 meters. The patients took 3366 ± 1694 strides/day, and were active for 272 ± 103 min/day. The cadence for the 30 highest, consecutive minutes of each day (15.1 ± 7.2 strides/min) was correlated with ICD ( r = 0.316, P < .001) and ACD ( r = 0.471, P < 0.001), and the cadence for the 60 highest, consecutive minutes of each day (11.1 ± 5.4 strides/min) was correlated with ICD ( r = 0.290, P < .01) and ACD ( r = 0.453, P < .001). Similarly, the cadences for the highest 1, 5, and 20 consecutive minutes, and the cadence for the 30 highest, nonconsecutive minutes all were correlated with ICD and ACD ( P < .05). None of the ambulatory cadences were correlated with ABI ( P > .05) or with ischemic window ( P > .05). Conclusion Daily ambulatory cadences are associated with severity of intermittent claudication, as measured by ACD and ICD, but not with peripheral hemodynamic measures.