Transversus abdominis and the superficial abdominal muscles are controlledindependently in a postural task

By manipulation of movement reaction time we investigated the co-ordination between the motor command for arm movement and the associated 'anticipator y' postural response of the abdominal muscles, Limb movement reaction time was varied by changing the expectation of ii mb movement direction required in a choice-reaction-ti me task, Ti mi ng of the 'anticipatory' postural c ontraction of transversus abdominis (TrA) was invariant while the limb move ment reaction time varied with changes in expectation of required response. In contrast, the timi ng of 'anticipatory' postural activity of the other abdominal muscles co-varied with limb movement reaction time. Dissociation of the behaviour of TrA and the other abdominal muscles suggests that TrA m ay be controlled independently of the motor command for limb movement in co ntrast to the other abdominal muscles. (C) 1999 Elsevier Science Ireland Lt d. All rights reserved.