Development of dynamic stability in children's rhythmic movement

This study examined the hypothesis that the stability of rhythmic motor patterns increases with developmental age in children. Children aged 6 and 10 years and adults (18- to 23-year-olds) rocked back and forth at their preferred amplitude and frequency while seated on a wooden box placed atop a force platform. Participants performed the seated rocking task with their feet supported and unsupported. There was an age-related decrease in rocking frequency and variability of the rocking cycle period, while the stability of the rocking dynamics increased, as indexed by the standard deviation of the phase angle of center of pressure motion. The presence of foot support decreased the stability of the rocking dynamics and reduced cycle period variability in the children, but not the adults. The results revealed that increments of age are associated with an increase in the stability of rhythmic motor patterns even when environmental conditions are altered.