Mean center of pressure in anteroposterior direction speed during right- and left-leg stance in the no-oscillation and oscillation conditions. Asterisks indicate significant differences between right- and left-leg stances. Daggers indicate significant differences between adjacent oscillation conditions in each leg. CoPap, Center of pressure in anteroposterior direction; No-osc, No-oscillation condition. *P < 0.05; †P < 0.05; †††P < 0.001.