| The development of locomotor and manipulative skills is first dependent upon the mastery of static and dynamic postures. This research documents the development of balance control skills, specifically as they relate to preservation of an upright bipedal posture. Two balance recovery strategies are of particular interest. The first behavior regains balance by repositioning the center of mass above the base of support without changing foot placement. The second behavior reestablishes control and a new base of support by stepping.; In the first study, 61 children, 9 months to 10 years of age, were grouped according to locomotor ability. The groups included standers, new, intermediate and advanced walkers, runners and jumpers, hoppers, gallopers and skippers. To test their balance, the children experienced support surface perturbations of varying severity. Analyses of conditions managed, without subjects collapsing or taking a step, revealed an increasing ability to withstand more severe perturbations with increasing developmental age. Hoppers, gallopers and skippers had faster recovery times, more efficient movement trajectories, greater muscle torque magnitudes and more refined torque patterns for transient perturbations compared to the lesser experienced groups. Multi-modal muscle torque patterns gave way to uni-modal patterns characterized by higher magnitudes and synchronous timing of peak muscle torques at each of the lower extremity joints. Results show a clear association between muscle torque regulatory abilities and improvement in balance.; The second experiment tested the emergence of stepping as a functional response for balance control. Twenty-five children, aged 9 to 19 months, with 0 to 6 months walking experience were exposed to support-surface perturbations. Despite their ability to execute voluntary stepping, novice walkers {dollar}({lcub}{rcub} 3{dollar} months walking experience) captured balance without moving their feet when exposed to small threats to balance, and employed the stepping response when the perturbation size increased. Three months of walking experience appears to be the threshold for transforming voluntary stepping into an automatic balance recovery response.; The practice of locomotor patterns and fine-tuning of torque modulation skills transform these coping behaviors into reliable and efficient strategies for balance control. |
