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Standing on a continuously moving platform: is body inertia counteracted or exploited?
S Corna1, J Tarantola, A Nardone
1Division of Physical Therapy and Rehabilitation, Rehabilitation Institute of Veruno, Salvatore Maugeri Foundation, IRCCS, Italy.
Experimental Brain Research
|February 16, 1999
Summary
Human balance control strategies shift with vision. With eyes open, the head is stabilized. With eyes closed, the body becomes more compliant, resembling an inverted pendulum.
Area of Science:
- Biomechanics
- Human Physiology
- Neuroscience
Background:
- Maintaining balance involves complex sensorimotor integration.
- Visual input significantly influences postural control strategies.
Purpose of the Study:
- To investigate head and hip displacement characteristics during anteroposterior translation.
- To analyze the impact of visual conditions (eyes open vs. eyes closed) on postural responses.
- To determine the relationship between body segment movements and balance control strategies.
Main Methods:
- Subjects stood on a moving platform with sinusoidal horizontal translation (0.1-1 Hz).
- Head, hip, and malleolus displacements were tracked using light-emitting diodes (LEDs).
- Quantification included shift, standard deviation, power spectrum, and cross-correlation analysis.
Main Results:
- With eyes open, head displacement was less than hip, which was less than malleolus.
- With eyes closed, this displacement order reversed.
- Cross-correlation decreased with increasing frequency, with greater decrease for head-to-malleolus.
- Head and hip power spectra showed peaks at platform frequency, larger with eyes closed.
Conclusions:
- Vision allows subjects to act as a non-rigid pendulum, stabilizing the head.
- Absence of vision shifts balance control to an inverted-pendulum strategy, increasing head oscillation.
- Postural control adapts by altering body compliance based on visual feedback.