Quiet stance control is affected by prior treadmill but not overground locomotion

Treadmill locomotion is different with respect to overground walking and may require an adapted control mode. The relevant neural computational eVort may produce lasting eVects encroaching upon the performance of a subsequent postural task. The hypothesis of the present study was that, contrary to overground walking, treadmill walking has eVects on quiet stance variables, in the assumption that the imposed locomotor activity is more critical to stance control than natural walking. Nine young subjects performed three diVerent walking sessions: treadmill with eyes closed, treadmill with eyes open, overground walking with eyes open. Body sway area and sway path and the position of the centre of foot pressure during stance were recorded by a dynamometric platform under control, postwalking and post-recovery conditions, alternatively with eyes closed and eyes open. At variance with overground walking, treadmill locomotion produced an eVect on body orientation in space during the subsequent stance trials. This consisted in a forward inclination of the body, not accompanied by increased body sway, lasting for a few minutes. Presence or absence of vision during treadmill locomotion did not induce diVerences in the amplitude or time-course of the post-eVect. We argue that body inclination would be the consequence of a change in the postural reference produced by a message arising from treadmill locomotion itself, possibly connected to particularities in the control mode of this type of walking.