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Footlift Asymmetry During Obstacle Avoidance in High-Risk Elderly

Authors

  • Richard P. Di Fabio PhD, PT,

    1. From the *Department of Physical Medicine and Rehabilitation, Doctoral Program in Physical Therapy, University of Minnesota, Minneapolis, Minnesota
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  • Wesley M. Kurszewski DPT(s),

    1. From the *Department of Physical Medicine and Rehabilitation, Doctoral Program in Physical Therapy, University of Minnesota, Minneapolis, Minnesota
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  • Erin E. Jorgenson DPT(s),

    1. From the *Department of Physical Medicine and Rehabilitation, Doctoral Program in Physical Therapy, University of Minnesota, Minneapolis, Minnesota
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  • Rachel C. Kunz DPT(s)

    1. From the *Department of Physical Medicine and Rehabilitation, Doctoral Program in Physical Therapy, University of Minnesota, Minneapolis, Minnesota
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  • This study was supported by grants to Dr. Di Fabio from the Fesler-Lampert Endowment for Aging Studies and the Minnesota Medical Foundation.

Richard P. Di Fabio, PhD, PT, Program in Physical Therapy, Mayo Mail Code 388, University of Minnesota, Minneapolis, MN 55455. E-mail: difab001@umn.edu

Abstract

Objectives: To test the hypothesis that vertical footlift asymmetries and low obstacle clearing distance during obstacle avoidance are characteristics of elderly people classified as high risk for falls.

Design: Controlled cross-sectional design with two conditions to cue selection of the foot-for-step initiation: sound cue and visual cue.

Setting: Senior independent living facilities.

Participants: Eighteen community-dwelling elderly with a history of falling or prolonged Timed Up and Go score greater than 13.5 seconds, 16 elderly with no fall history and Timed Up & Go score of 13.5 seconds or less, and 15 younger subjects.

Measurements: Video kinematic analysis of bilateral footlift displacement and velocity using reflective markers as subjects stepped over foam obstacles scaled to a maximum tolerated height.

Results: High-risk elders contacted the obstacle more frequently and had significantly greater vertical footlift asymmetries adjusted for obstacle/subject height (mean±standard error asymmetry index for sound cue 3.25±0.42 cm, for visual cue 2.51±0.45 cm) than low-risk and younger subjects (P<.001). In low-risk elderly and younger subjects, the asymmetry index approached 0, which indicated symmetrical lower limb movements when stepping over the obstacles.

Conclusion: High-risk elderly show a marked asymmetry in foot clearance while stepping over an obstacle, with the lag foot clearing the obstacle at a much lower distance than the lead foot. Possible mechanisms responsible for these findings (limited hip extension and deficits in executive cognitive function) are discussed.

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