The step cycle organization of infant walkers.

To walk independently, the human infant must coordinate its multisegmented body to achieve both postural stability and forward mobility. In this experiment, we sought evidence of the form this coordination takes in infants who have been walking 3 to 10 months. Using the Philippson phases to represent the step cycle, we analyzed film records of infants and adults walking at speeds from 2 to 4 km/hr. Our results reveal a clear relationship between walking speed and the F and E(3) Philippson phases of the step cycle in both the young walkers and the adults. Indeed, across all four phases of the step cycle, the infants exhibited an organization that was almost identical to that of the mature walkers.