Changes to the gait initiation programme following a running exercise in human subjects

The question addressed by the present study was whether the programme for gait initiation is fully invariant or can be modified by a prior long duration running exercise. Eight subjects performed a series of gait initiation movements on a force platform in three different speed conditions before and after running on a treadmill (3.3 m/s, 0% slope). Following the running exercise, the first step length and velocity were greater and the double stance phase duration was shorter, while the relationships between the temporal parameters of gait initiation and the velocity of the centre of gravity at the end of the first step were not significantly different. During the anticipation phase, the maximal variation of the ankle joints moment remained significantly correlated with the integrated EMG activity of the Tibialis Anterior after the run. However the displacement of the centre of foot pressure, displayed some post-exercise changes, indicating a modification to the postural part of the gait initiation programme. The greater velocities reached after the running exercise could be explained by a recalibration of gravitational force control, while the invariance of time necessary to reach these velocities showed the rigidity of the initiation gait.