Figure 2.

(A) Ball angle, cup position (dashed lines), and velocity, applied force, and energy margin for the young (blue) and older (red) subjects. Individual subjects are shown as thin lines, group averages are the thick lines. (B) Example of a representative ball and cup transit of an older subject in late practice [shown in (A)]. Images are at 5% increments of the total movement time. The color of the ball represents the energy margin; dark blue represents a high energy margin (“safe”) and dark red represents a low energy margin (“unsafe”). The arrows scale with the force applied to the cup. The size of the ball was enlarged for clarity.