Abstract
The purpose of this study was to measure quantitative changes of postural sway after vibratory stimulation. The subjects of this study were 22 healthy young persons, ranging in age from 19 to 23 years old.
A rotating vibrator (Heiwa E.I.TMT-18, amplitude; 1.5-2.0 mm, weight; 500 g) was fixed by an elastic bandage on the upper parts of the bilateral Achilles tendons, while the subjects were standing upright on a stabilogram (IG 06 SANEI).
Vibratory stimulation was performed at a frequency of 70 Hz or 130 Hz for variable times (e.g. 30 second, 1, 2 and 3 minute). The total length and area of sway center of gravity was measured for 30 second immediately after the vibratory stimulation had been stopped.
Results were as follows ;
1) The total length and area of sway of gravity at the frequency of 70 Hz was increased more compared with that at the frequency of 130 Hz with the eyes closed.
2) The ratio of the total length of body sway with the eyes closed to that with the eyes open under the vibratory loading for 30 second was higher than for 1 min. over.
On the basis of results, it was suspected that 30 second-vibration loading with the frequency of 70 Hz was more effective for proprioceptors of antigravity muscles than that with the frequency of 130 Hz.
