Human equilibrium on unstable support: The importance of feet-support interaction

Y. P. Ivanenko, Y. S. Levik, V. L. Talis, V. S. Gurfinkel

Research output: Contribution to journalArticlepeer-review


Healthy humans maintained equilibrium on rocking supports (seesaw) of different curvatures and heights. We recorded platform tilt, horizontal displacements of the upper body, ankle joint angle and activity of ankle joint muscles. Subjects maintained balance by making seesaw rotations placing the support under the body's centre-of-gravity. Forward displacement was balanced by compensatory plantariflexion: thus the relation between muscle activity and ankle joint angle differed from that on a rigid floor. Mechanical analysis of stability showed that standing on low seesaws requires ankle torque increase during forward body shift (as on a rigid floor) and torque decrease on high seesaws (when the seesaw height exceeded its radius). In the latter case, balancing was impossible with eyes closed. The results suggest that directionally specific torque changes in response to centre-of- gravity shifts provide important information for maintenance of orthograde posture.

Original languageEnglish
Pages (from-to)109-112
Number of pages4
JournalNeuroscience Letters
Issue number3
Publication statusPublished - Oct 17 1997


  • Equilibrium
  • Feet-support interaction
  • Human
  • Postural reference
  • Unstable support

ASJC Scopus subject areas

  • Neuroscience(all)


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