GI is typically associated with anticipatory postural adjustments (APAs) and occurred prior to gross segmental movement and stability-boundary changes of the first step.
APAs mean that the onset of postural changes occurs prior to the onset of the postural disturbance due to the movement. They also mean that a feed-forward postural control is associated with the movement control that pre- vents the occurrence of movement-related posture and equilibrium disturbances. Specifically, the control of equi- librium during leg movements is interesting to analyse because the moving limb is involved in body support. Movements of the leg change the support conditions and entail a shift of the centre of gravity position prior to movement onset [3].