Physical activity, functional capacity, and step variability during walking in people with lower-limb amputation

- We test on a group of amputees.
- We quantify variability with the coefficient of variation.
- Physical activity (PA) is highly related to gait speed and functional capacity.
- A higher PA is related to a lower step length variability if speed varies little.
- A higher PA is related to a larger step width variability if speed varies little.

Physical activity is important for general health. For an individual with amputation to sustain physical activity, certain functional capacity might be needed. Gait variability is related to the incidence of falls. This study explored the relationship between physical activity and a few common performance measures (six-minute walk test, step length variability, step width variability, and comfortable walking speed) in individuals with unilateral lower-limb amputation. Twenty individuals completed the study (age: 50 ± 11 yrs). Twelve of them had transtibial amputation, seven had transfemoral amputation, and one had through-knee amputation. Gait data was collected by the GaitRite instrumented walkway while participants performed a 3-min comfortable walking trial followed by a six-minute walk test. Physical activity was indicated by the mean of 7-day step counts via a pedometer. Gait variability was calculated by the coefficient of variation. Pearson correlation analysis was conducted between physical activity level and the 4 performance measures. Significance level was set at 0.05. Physical activity correlates strongly to comfortable walking speed (r = 0.76), six-minute walk distance (r = 0.67), and correlates fairly to step width variability (r = 0.44). On the contrary, physical activity is inversely related to step length variability of the prosthetic leg (r = −0.46) and of the sound leg (r = −0.47). Having better functional capacity and lateral stability might enable an individual with lower-limb amputation to engage in a higher physical activity level, or vise versa. However, our conclusions are only preliminary as limited by the small sample size.