Sagittal plane angular range of motion of the center of mass with respect to the center of pressure over 28 days of testing. Controls are represented by the dashed line. Concussed are represented by the solid line. Standard error bars are presented. (a) Indicates statistical difference (p = 0.041) between the two groups on a particular day. (b) Indicates statistical (p = 0.001) from all other days in a particular group.