During the early school years, a number of children present with specific coordination problems and display poor perceptual-motor skills. This condition is recognized as developmental coordination disorder (DCD), a deficit in the development of motor skills that is not directly associated with any mental retardation or physical disorder. In order to better understand the neural mechanism of motor control for the children with DCD, it would be valuable to investigate the temporospatial parameters as well as the parameters extracted from frequency analysis for children with DCD during treadmill walking with the electromyography measurement of the muscles in lower extremity. Forty six children, including 14 normal children, 11 children with borderline DCD and 21 children with DCD, were recruited in this study. Ten surface EMG electrodes were used in this study. The medial gastrocnemius, tibialis anterior, rectus femoralis, hamstring and gluteus maximum were measured bilaterally. The data were collected at the first 15 seconds of each minute within thirteen-minute treadmill walking. The variance ratio, mean frequency and median frequency were computed to compare the difference between normal children and the DCD children. The mean and median frequency values of the DCD group were substantially lower than those of normal group. It is implied that the muscles of the DCD children may have the higher risk or higher trend of muscle fatigue during long term activities. Also, the comparison between right and left sides were evaluated for bilateralism of the treadmill walking. DCD children tended to have more muscles with significant differences for the values of variance ratio during the treadmill walking. It is implied that the bilateralism of walking for the DCD group may be not as good as the normal children.
