Study of anticipatory postural adjustments in an air pistol-shooting task

A segmental teleokinetic movement performed from an upright standing position is usually preceded by a sequence of postural movements having the goal of counteracting the imbalance which will be caused by the forthcoming movement. This study had two aims, (1) to verify whether the postural component was programmed in the same way as that of the teleokinetic component and (2) to verify whether the postural component was specific to the direction and speed of the movement. 12 participants performed a pistol-shooting task involving a rapid arm-raising movement. Three directions, two time deadlines, and three types of cue were manipulated. This study showed that the postural component was sensitive to the cue effects, the characteristics of anticipatory postural adjustments were specific to the direction of the movement, and the characteristics of the postural muscle EMG burst were the same whether the participants programmed or deprogrammed and reprogrammed their movements for a given direction. The speed parameter did not seem to have any significant influence on the characteristics of the anticipatory postural adjustments.