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Analysis of human postural responses to recoverable fallsWe studied the kinematics and kinetics of human postural responses to "recoverable falls." To induce brief falling we used a Hold and Release (H&R) paradigm. Standing subjects actively resisted a force applied to their sternum. When this force was quickly released they were suddenly off balance. For a brief period, approximately 125 ms, until restoring forces were generated to shift the center of foot pressure in front of the center of mass, the body was in a forward fall acted on by gravity and ground support forces. We were able to describe the whole-body postural behavior following release using a multilink inverted pendulum model in a regime of "small oscillations." A three-segment model incorporating upper body, upper leg, and lower leg, with active stiffness and damping at the joints was fully adequate to fit the kinematic data from all conditions. The significance of our findings is that in situations involving recoverable falls or loss of balance the earliest responses are likely dependent on actively-tuned, reflexive mechanisms yielding stiffness and damping modulation of the joints. We demonstrate that haptic cues from index fingertip contact with a stationary surface lead to a significantly smaller angular displacement of the torso and a more rapid recovery of balance. Our H&R paradigm and associated model provide a quantifiable approach to studying recovery from potential falling in normal and clinical subjects.
Document ID
20040087630
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Bortolami, S. B.
(Brandeis University Waltham, MA 2454-9110, United States)
DiZio, P.
Rabin, E.
Lackner, J. R.
Date Acquired
August 21, 2013
Publication Date
August 1, 2003
Publication Information
Publication: Experimental brain research. Experimentelle Hirnforschung. Experimentation cerebrale
Volume: 151
Issue: 3
ISSN: 0014-4819
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Space Human Factors
Non-NASA Center

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