Anticipatory postural adjustments contribute to age-related changes in compensatory steps associated with unilateral perturbations

Masaki Hyodo, Mayumi Saito, Junichi Ushiba, Yutaka Tomita, Mihoko Minami, Yoshihisa Masakado

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Compensatory steps are essential for preventing falls following perturbations. This study aimed to explore age-related changes in compensatory steps to unilateral perturbations, specifically in terms of whether anticipatory postural adjustments (APAs) play a role in stabilizing lateral balance. Five young and five elderly male adults participated. The split-belt treadmill was used to provide bi- and unilateral perturbations, as forward or backward transitions, applied 10 times in random order. Backward steps evoked by unilateral forward perturbations were evaluated. We measured temporal characteristics, mediolateral (ML) center of mass (COM) motion, and ML step length of compensatory steps. Compensatory steps to unexpected perturbations showed delayed onset of foot-off (FO) and expanded lateral swing length in elderly compared to young subjects. Differences in COM motions and step width arose related to APAs. Elderly subjects showing APAs exhibited no significant differences in ML COM, ML COM velocity, or ML swing length compared to young subjects. However, elderly subjects without APAs showed significant changes toward instability in these parameters. The fact that APAs play a notable role, particularly in the elderly, in stability offers a new insight into preventing falls. However, APAs occurred in 29% of the steps of young and 35% of the steps of elderly subjects. If the occurrence of APAs in elderly people in response to compensatory steps was more frequent, fall risk would be reduced. Further studies, particularly into APA frequency, might contribute to improved intervention to prevent falls.

Original languageEnglish
Pages (from-to)625-630
Number of pages6
JournalGait and Posture
Issue number3
Publication statusPublished - 2012 Jul 1


  • Age-related change
  • Anticipatory postural adjustment
  • Compensatory step
  • Split-belt treadmill
  • Unilateral perturbation

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Rehabilitation


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