Volume 91, Issue 4 , Pages 589-595, April 2010
Knee Extensor Strength, Dynamic Stability, and Functional Ambulation: Are They Related in Parkinson's Disease?
Abstract
Nocera JR, Buckley T, Waddell D, Okun MS, Hass CJ. Knee extensor strength, dynamic stability, and functional ambulation: are they related in Parkinson's disease?
Objective
To evaluate the relationship between knee extensor strength, postural stability, functional ambulation, and disease severity in Parkinson's disease (PD).
Design
A cohort study.
Setting
University research laboratory.
Participants
Patients (N=44) with idiopathic PD.
Intervention
Not applicable.
Main Outcome Measures
Participants were evaluated on their isokinetic knee extensor strength. Additionally, participants completed an assessment of their postural stability (Functional Reach Test for static stability and a dynamic postural stability assessment as measured by the center of pressure–center of mass moment arm during gait initiation). Participants also underwent an evaluation of their functional ambulation as measured by a 6-minute walk test. Lastly, participants were evaluated by a neurologist specially trained in movement disorders to assess neurologic status and disease severity using the Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr disability score.
Results
Knee extensor strength positively correlated with dynamic postural stability and negatively correlated with disease severity. Further, dynamic postural stability was negatively correlated to disease severity and positively correlated with functional ambulation in this cohort of patients with PD (P<.05). The results also suggest that the Functional Reach Test may be a valuable assessment tool to examine postural stability in PD.
Conclusions
These findings suggest a malleable relationship between knee extensor strength, dynamic stability, and disease severity in PD. Although strength is only one piece of the puzzle in the functional outcome of PD, these findings may assist clinicians in designing appropriate interventions aimed at increasing function and decreasing fall risk in PD.
Key Words: Movement disorders, Neurodegenerative diseases, Rehabilitation
Abbreviations: COM, center of mass, COP, center of pressure, HY, Hoehn and Yahr, PD, Parkinson's disease, UPDRS, Unified Parkinson's Disease Rating Scale
Supported by the National Institute on Deafness and other Communication Disorders (grant no. T32DC008768), and the UF National Parkinson's Foundation Center of Excellence.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.
PII: S0003-9993(09)00996-4
doi:10.1016/j.apmr.2009.11.026
© 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.
Volume 91, Issue 4 , Pages 589-595, April 2010
