Date of Award

Fall 12-2017

Degree Type

Dissertation

Degree Name

PhD Health Sciences

Department

Health and Medical Sciences

Advisor

Genevieve Pinto Zipp, Ed.D.

Committee Member

Preeti Nair, Ph.D.

Committee Member

Raju K. Parasher, Ed.D.

Keywords

Turning strategies; Complex locomotor skills; Age-related differences and turn strategies; Anticipatory v. reactive spatial-temporal gait adaptations; Fast walking speed & late-visual cue constraints; Spatial constraints; Personal space margin of safety; Fall prevention gait training; Healthy older adults at low fall risk; Spin-turn, step-turn, mixed-turn; Walking turns

Abstract

Hip fractures can be life-threatening, debilitating, and costly. The odds for hip fracture increases from impact of sideways falls. While turning has been strongly associated with hip fracture & sideways falls, the distinction between the risks for walking-turns as opposed to low-velocity in-place turning is not clear. The present study sought to fill a gap as previous research had not compared walking-turn performance in young & healthy older adults at low-fall risk within the same study and response-conditions of speed interacting with direction-cue time constraints. Spatial-temporal variables representative of AP braking/propulsion (i.e. stride-length & speed) & ML stability (left/right H-H BOS) were collected with the Gaitrite upon approach of a turning zone whose entrance width was just 73 cm; and turn-strategy categorical data for stable wide-BOS step-turns, biomechanically challenging narrow-BOS spin-turns, and combined subtypes of mixed-turns either of the “extra-step” variety representative of an AP stability/braking issue or “small-amplitude” variety representative of a ML stability/balance issue were captured on video. Mixed-ANOVA of gait measures for AP propulsion/braking revealed no age-group differences in speed despite a trend for less of a fast-pace increase in elderly stride-length, yet similar anticipatory slowing and shorter strides approaching turns. Measures of ML stability revealed similar anticipatory widening of right BOS approaching turns, and a three-way interaction showed both had similar anticipatory narrowing of left BOS when approaching turns at fast-pace and similar reactive narrowing of left BOS following an unexpected turn-cue at preferred pace. Loglinear analysis of turn-strategies revealed no age-related associations as both preferred mixed-turns the least. At fast speeds preference for spin-turns decreased, yet when late-cued preference for both step-turns and spin-turns decreased 5.5-fold & 4.0-fold, respectively, indicating other factors besides biomechanical. Furthermore, the standardized residual reached significance for the elderly mixed-turns cell at the most constrained fast-speed*late-cue response-condition, with the “extra-step” sub-type contributing greatest possibly implying an AP rather than ML stability issue. The findings suggest that when approaching turns across an interaction of response-time conditions, healthy older adults show similar anticipatory/reactive gait adaptations and turn-strategy preferences with regards to AP propulsion/deceleration and ML stability/balance. In conclusion, within study limits, fall-prevention gait-training for healthy elderly with low-fall-risk and no age-related speed declines, in addition to addressing important ML stability issues of turn execution, are best served by not losing sight of the fundamental prerequisite to arrest forward momentum upon approach, and being inclusive of spin-turns for their ML space-efficiency.

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