Frequency spectral characteristics of standing balance in children and young adults.

Past research has shown that spectral frequency characteristics of a balance control system may be useful for early detection of minor changes in the system. Since there is a lack of information regarding the frequency spectrum of children's balance control system, this study was undertaken to investigate and compare the spectral frequency characteristics of standing balance control between children and young adults under altered sensory environments. Seventeen children (9 females, 8 males, mean age 7.8+/-0.9 years) and the same number of female and male young adults (mean age 21.1+/-1.3 years) were tested for standing balance under six sensory conditions. These conditions were created by crossing the three levels of the visual factor (open eye, closed eye, sway-referenced vision) with the two levels of the somatosensory factor (fixed foot support, compliant foot support). The median spectral frequencies of the shear forces in the anterior-posterior (A/P) and the medial-lateral (M/L) directions were used as dependent variables. The results showed that children had higher median spectral frequency of the A/P shear force than young adults and this difference was not affected by the somatosensory factor. The median spectral frequency in the M/L direction was not different between the groups. The higher rate of body mass vibration of children in the A/P direction implies that children may not have fully developed the ankle strategy for maintaining standing balance, but nonetheless have developed the same efficiency of using vision for their reference of standing balance.