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Step length as the primary determinant of minimum foot clearance during overground gait in Parkinson’s disease. World Congress of the International Society for Posture and Gait Research

Lookup NU author(s): Dr Lisa Alcock, Dr Brook Galna, Dr Susan Lord, Professor Lynn Rochester

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Abstract

BACKGROUND AND AIM: Subtle alterations in foot clearance are evident even in the early clinical stages of Parkinson’s disease (PD)[1] and may contribute to the increased risk of trips and falls in this population. It remains unclear whether these changes are solely due to walking more slowly and with shorter steps[2]. People with PD tend to walk with shorter steps for any given walking speed, which may further exacerbate impairments in foot clearance. However, when asked to walk at faster speeds, the temporal (time) and spatial (length) composition of gait in PD becomes more similar to that of older adults[3]. A more comprehensive observation of the changes in temporal-spatial characteristic when walking at different speeds and the resulting foot trajectories will enhance our understanding of the temporal-spatial determinants of foot clearance in people with PD and so inform the design of falls prevention therapies.METHODS: Thirty-six people with PD and 38 age-matched controls completed four intermittent walks at a self-selected preferred and fast gait velocity. Temporal-spatial characteristics of gait were obtained using an instrumented walkway and foot clearance outcomes (minima, maxima and trajectory gradients)[1] measured with 3D motion capture. General Linear Models evaluated the influence of group (PD, Control) and condition (Preferred gait velocity, Fast gait velocity) upon gait and foot clearance. Linear regression quantified the variance in minimum foot clearance (MFC) attributed to temporal-spatial gait (velocity, length, time and the walk ratio).RESULTS: People with PD walked faster than controls, regardless of condition (p<.001). Both groups reduced their swing time when walking faster, but this was less evident in people with PD who tended to increase their step length (evidenced by changes in the walk ratio) more than controls (group x condition interaction, p=0.018). Walking faster resulted in increased minima and maxima at both the heel and toe and steeper take-off (toe) and landing (heel) gradients (p<.001). Step length and the walk ratio were most strongly related to MFC in both groups and velocity conditions (Figure 1) however the change in temporal-spatial control to increase gait velocity (i.e. Step lengthFast velocity – Step lengthPreferred velocity) did not explain the change in MFC (i.e. MFCFast velocity – MFCPreferred velocity) in PD.CONCLUSIONS: Increasing step length when walking faster, rather reducing swing time, is responsible for increased MFC in older adults and people with PD. Interventions that specifically address the short step length often observed in people with PD may also improve MFC and so may reduce the risk of trips and falls.REFERENCES[1]Alcock (2016). J Biomech, 49(13),pp.2763-2769. [2]Morris (1996). Brain, 119(2),pp.551-568. [3]Cho (2010). J Neurophys, 103(3),pp.1478-1489.


Publication metadata

Author(s): Alcock L, Perkins R, Galna B, Lord S, Rochester L

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: World Congress of the International Society for Posture and Gait Research

Year of Conference: 2017

Print publication date: 27/06/2017

Online publication date: 27/06/2017

Acceptance date: 27/06/2017


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