Normal and impaired development of children's gait.

The development of bipedal locomotion was studied electrophysiologically in 50 children, ages varying between 6 months and 7 years. The typical features of the immature gait were: A co-activation of antagonistic leg muscles during the stance phase. With the development of free walking the activity pattern gradually became more reciprocally organized. Up to an age of 4 years, large solitary biphasic potentials in gastrocnemius with segmental latency after the muscle was stretched as the forefoot reached the ground. A reduced magnitude of gastrocnemius-EMG at the early stages of stepping. While the magnitude of tibialis anterior EMG did not change substantially with the maturation of gait, the final magnitude of gastrocnemius activity was established around 4-5 years. In the early stages of gait development, preprogrammed leg muscle EMG in form of the co-activation, and segmental stretch reflex activity appear separately. It is conjectured that during the course of maturation, the integration of the stretch-reflex activity into the preprogrammed leg muscle EMG corresponds to an increase of gastrocnemius activity with optimal adaptation to the environment. The locomotor pattern of older children with cerebral palsy showed a striking similarity to the early stages of gait development in healthy children.