While innumerable indicators of age-related gait change exist, almost none integrate or summarize segmental coordination during movement. Planar Covariation of Elevation Angles (PCEA) was developed to study gait changes during development, but may help characterize age-related changes. PCEA reflects coordination among leg segment angles relative to vertical (thigh, shank and foot), resulting in a loop that lie in a plane and rotate with increasing walking speed. We assessed PCEA features among Baltimore Longitudinal Study of Aging adults without diagnoses known to affect gait, comparing young (n=35, age 40.1 ± 6.8) and old (n=36, age 84.5 ± 3.0) at usual and fast walking speeds. Principle component analysis of EAs yields 3 eigenvectors (u1~3) with corresponding variance (v1~3) that describe the degree of planarity, the shape of the loop and the orientation/rotation of the plane. We also assessed the segmental phase differences underlying PCEA. Degree of planarity did not differ by age or speed. Age affected loop shape; older adults had wider loops than young at both speeds. In older adults compared to young, the plane rotated less during fast walking, with less tightly-coupled thigh-shank segments. Older adults showed greater variability in the thigh’s contribution to the 1st eigenvector and in the shank-foot phase difference. PCEA provides a new integrated perspective on multi-segment coordination during gait and detects age effects. Decreased plane rotation with aging may indicate higher energy cost and less tightly coupled thigh-shank segments during walking. PCEA characteristics may help identify and profile age-related gait impairments and target intervention strategies.
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