Control strategies for initiation of human gait are influenced by accuracyconstraints

The accuracy of placement of swing limb heel-strike was used to determine s trategies of motor control of the stance limb during gait initiation (GI). Subjects initiated gait as fast as possible with the swing limb heel-strike landing on either a small or large target. Stance limb ground reaction for ces, electromyogram duration and temporal data for GI were measured. It was hypothesized that accuracy would affect movement speed and the rate of ris e, or the slope, of the ground reaction forces that control GI. The slopes of the stance limb forces that coincide with swing limb toe-off remained in variant. However, the slopes of forces and peak forces related to swing lim b heel-strike were significantly less for the small target. These initial d ata suggest that principles of upper extremity motor control may be general ized to the initiation of movement from upright stance. (C) 2000 Elsevier S cience Ireland Ltd. All rights reserved.