Acquisition of upper body stability during walking in toddlers.

This study examines the development of head and trunk movements in toddlers as they begin to walk independently. The data are from a longitudinal study of 7 infants observed from the onset of walking over a period of 46-80 weeks. Head and trunk rotations were measured in the frontal and sagittal planes together with global gait parameters (progression velocity, step cadence, length and width, duration of double support phase). The results showed that during the first weeks of walking head and trunk oscillations significantly decreased, indicating that considerable progress is made in upper body stabilization. Dramatic changes in global gait parameters also occurred at this time. After this first period of rapid changes, gait parameters continued the same developmental trend but with slower changes. The close relation between gain in head and trunk stability and improvement in walking efficacy is discussed on the basis of the individual developmental trends.