Effects of linear movements on upright standing position

This study investigated the effects of antero-posterior movement on the upright standing posture in the humans. Subjects were asked to stand on a platform in a linear accelerator (sled) in the dark. At a fixed distance of sled movements in an antero-posterior direction, peak speed was changed by sin...

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Bibliographic Details
Published inEnvironmental medicine : annual report of the Research Institute of Environmental Medicine, Nagoya University Vol. 40; no. 2; p. 193
Main Authors Kawakami, O, Sudoh, H, Watanabe, S
Format Journal Article
LanguageEnglish
Published Japan 01.12.1996
Subjects
Acceleration
Adult
Ankle
Electromyography
Head
Hip
Humans
Knee
Leg
Movement
Muscle, Skeletal - physiology
Postural Balance - physiology
Posture - physiology
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ISSN0287-0517

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Summary:This study investigated the effects of antero-posterior movement on the upright standing posture in the humans. Subjects were asked to stand on a platform in a linear accelerator (sled) in the dark. At a fixed distance of sled movements in an antero-posterior direction, peak speed was changed by sinusoidal modes run at 0.02 G, 0.04 G, 0.06 G and 0.08 G. At lower speeds (0.02 G and 0.04 G) joints moved in parallel, but at higher speeds (0.06 G and 0.08 G) the hip flexed or extended in the direction of the sway. At lower speeds (0.02 G and 0.04 G) EMG in lower leg exhibited co-activated patterns in both forward and backward accelerations at lower speeds (0.02 G and 0.04 G), but at higher speeds (0.06 G and 0.08 G) TA was activated with reciprocal inhibition of GC to maintain the body in equilibrium in a reflexive manner. This reciprocal inhibition may be due to main reflex control elicited by motor functions as a result of the linear acceleration. The threshold of speed was assumed to be from 0.04 G to 0.06 G for all but one subject.
ISSN:0287-0517