Dopamine replacement therapy normalizes reactive step length to postural perturbations in Parkinson's disease

Cara Herbers, Joseph Schroeder, Chiahao Lu, Helen Geng, Raymond Zhang, Jessica Mehregan, Kada Malakowsky, Arthur Erdman, Matthew D. Johnson, Scott Cooper

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Background: Postural instability is one of the most disabling motor symptoms of Parkinson's disease (PD) given its association with falls and loss of independence. Previous studies have assessed biomechanical measures of reactive stepping in response to perturbations, showing that individuals with PD exhibit inadequate postural responses to regain balance. Research question: Does dopamine replacement therapy normalize step length in response to balance perturbations? Methods: In this study, we estimated reactive step length, to a postural perturbation, retrospectively from a dataset of frontal plane video using 2D motion tracking and direct linear transform methods. We compared two perturbation methods: support surface translation and shoulder pull (the clinical standard) in 14 individuals with PD and 13 without PD (on and off medication), with and without partial body weight support (BWS). The primary outcome was the length of the first step taken to regain balance after the perturbation analyzed with mixed effects ANOVA, with post hoc analysis of anteroposterior (AP) and mediolateral (ML) components. Results: PD OFF medication exhibited shorter reactive step length compared to PD ON and compared to control groups for the surface translation perturbations, but no significant difference was observed for the shoulder pull perturbations. Significance: Dopamine replacement therapy affects step length in response to perturbation more robustly for surface translations than for a pull by the shoulders.

Original languageEnglish (US)
Pages (from-to)95-100
Number of pages6
JournalGait and Posture
StatePublished - Mar 2023

Bibliographical note

Funding Information:
This work was supported by the National Institutes of Health [ P50-NS098573 , P50-NS123109 , R01-NS124814 ] and the National Science Foundation Graduate Fellowship Program [to CH]. We thank Dr. Joshua Aman for his contribution to the design and construction of an apparatus used during all perturbation sessions.

Publisher Copyright:
© 2023 Elsevier B.V.


  • Balance
  • Levodopa
  • Parkinson's disease
  • Postural Instability
  • Step Length

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, N.I.H., Extramural


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