A base and method of using a base on a treadmill in which the base comprises three or more first ball bearing assemblies, each ball bearing assembly comprising a ball and a mounting assembly, the base also comprising one or more lower ball bearing assemblies, each lower ball bearing assembly comprising a lower ball and a lower mounting assembly, wherein each lower ball bearing assembly projects down from a plane defined by three or more of the ball bearing assemblies. A base may be attachable to or integrated into a piece of sports footwear or a board of a board sport. A user standing on footwear or a board with one or more bases may rock in one or more direction on the sports footwear to produce a leaning effect wherein one or more lower ball bearing assemblies and two or more ball bearing assemblies contact the ground.