Multi-sensory systems, including the visual, somatosensory, and vestibular ones, are involved in maintaining standing balance. The organization of these sensory systems is as important as the efficiency of each individual system in maintaining optimal balance. The purpose of the present experiment was to investigate the developmental changes in static standing balance and sensory organization under altered sensory conditions. This study involved 64 children (from 4 to 15 years of age) and 17 young adults. The children were divided into four age groups: 4~6, 7~9, 10~12, and 13~15 years. Static standing balance was assessed with the one-leg standing test under four different sensory conditions: the children stood on a firm surface with (1) eyes open or (2) closed, and they stood on a foam surface with eyes (3) open or (4) closed. In balancing ability, the age groups exhibited significant differences. The function of sensory organization for balance control was poorer for the children than for the young adults. The functional efficiency of the somatosensory system of the children aged 7~9 years was at the young adults' level, and the visual function of the children aged 10~12 years had also reached the young adults' level. However, the functional efficiency of the vestibular system of children was significantly lower than that of the young adults, even at the age of 15 years. This may indicate that sensory organization and standing balance are still developing after the age of 15 years.

The purpose of this study was to investigate whether the standing balance could be influenced by the different foot positions. Seventeen patients with hemiplegia were tested for the static and dynamic balance under the different foot positions. In the balance test, subject stood by bearing weight on one foot, and the other foot was positioned in three different positions (symmetric, anterolateral, and anterior position). This study used the Kinesthetic ability trainer (KAT2000) to measure the standing balance. The results were as follows: 1) There were significant differences in the static standing balance in different foot positions with both weight-bearing on the paretic limb and on the nonparetic limb (p<.05). 2) There were also significant differences in the dynamic standing balance in different foot positions with both weight-bearing on the paretic limb and on the nonparetic limb (p<.05). 3) There was a significant difference when the paretic weight-bearing and the nonparetic weight-bearing were compared (p<.01). 4) when the paretic weight-bearing and the nonparetic weight-bearing were compared, anterior foot position showed a significant difference in the dynamic standing balance (p<.05), but anterolateral foot position did not show a significant difference (p>.05). In this study, the standing balance showed a significant difference according to different foot positions in hemiparetic patients, and standing balance was better when they stood by bearing weight on the nonparetic limb. These results indicate that it is a necessary to consider both weight-bearing limb and foot position not only in the rehabilitation program but also in achieving the stability in the independent life.