DEVELOPMENT OF LOCOMOTOR BALANCE CONTROL IN HEALTHY-CHILDREN

A set of experimental studies showing how inter-segmental coordination develops during childhood in various locomotor tasks is reviewed. On the basis of these results and two functional principles (stable refer ence frame and control of the degrees of freedom of the body joints), we recently proposed an ontogenetic model for the sensorimotor organiz ation of balance control in humans (5). In this model, the hypothesis was put forward that the two main modes of equilibrium control (ascend ing vs descending temporal organization) operate alternatively and are associated with either of two modes of head-trunk linkage ('en bloc' vs articulated) during four successive periods in the course of ontoge nesis. The advantage of this model is that it is heuristic and therefo re open to further improvements, including the generalization of these balance strategies to most of the posture-kinetic activities, the com parison between unperturbed natural balance and reactions to postural disturbances. Some improvements are suggested, and are illustrated by the studies of intersegmental coordination in new experimental tasks s uch as hops using one foot or two feet and the initiation of gait. The se new results are consistent with the idea that mastery of the degree s of freedom to be controlled simultaneously during the movement impro ves gradually with age. Moreover, they support the concept of multiple reference frames which operate in a complementary manner or in concer t to permit the most appropriate organization of balance control, depe nding on the environmental requirements. (C) 1998 Elsevier Science Ltd . All rights reserved.