Integration of the hand in postural reactions to sustained sideways force at the pelvis.

In order to investigate the potential hand contribution to sideways balance, sideways pushes to the right, which subjects resisted using either the lower limbs ("hip only") or the lower limbs assisted by the right upper limb ("hand and hip"), were delivered to the pelvis. Analysis of force and electromyogram recordings from the legs, arm and hand in the hand-and-hip condition showed a close co-ordination of upper and lower limbs in terms of mean latencies and amplitudes. However, trial to trial fluctuations of forces generated by the hand and leg did not correlate, suggesting parallel pathways under central co-ordinative control.