Development of body equilibrium control in elementary school children was examined by analysing movement of the center of gravity (CG) during maintenance of an upright stance under various visual conditions. Eightyfour healthy subjects aged 7 to 12 years were instructed to stand in the Romberg position on a force plate for 30s with the eyes open, eyes closed, or eyers restricted to a 15-degree visual field. The length of trace, root mean square (RMS), and the power spectra of fore-aft CG movement were calculated by a personal computer.
The results were as follows;
1. The length of trace and RMS of CG increased in accordance with the decrease in the amount of visual information, and consequently increased in order: eyes closed, restricted visual field, eyes open.
2. The length of trace and RMS of CG for boys decreased with increasing age, but none of these factors in girls was related to age.
3. The power spectrum analysis of CG movement showed a peak of power at 0.4 to 0.7 Hz during both eyes closed and eyes restricted.
4. This feature was shown in all age groups for girls, but only in the 11 to 12-year age group for boys.
5. The greater the decrease in the length and the RMS of CG with increasing age, the higher the amplitude of the power spectrum peak.
In conclusion, it was clarified that stability of posture in elementary school children is dependent upon the amount of visual information. The characteristics of the change in frequency zone manifested by decreasing the amount of visual information may reflect the developmental process of visual postural control in children.