Gait function ( gait velocity , stride length , double support phase , single-step variability left and right ) was assessed at baseline , after 3-weeks of WBV intervention or sham WBV , 4-weeks after baseline , and 5-weeks after baseline using a mobile plantar food pressure system and the `` Timed Up and Go '' test under four different gait conditions ( comfortable overground gait , comfortable gait on treadmill , -20 % comfortable gait velocity on treadmill and +20 % comfortable gait velocity on treadmill ) .