Fig 4. EMG-ball coupling.

Representative example of the relation between the net EMG signal (x-axis) and the required distance (cm) to intercept the ball (y-axis) during a full trial of Breakout-EMG (Note that distance is actually expressed in units specific to the program used to design the game. However, on the monitor we used, these units are approximately equivalent to centimeters.). The net EMG signal has no unit of measurement but is the integral of the difference between the flexor and extensor EMG signal over the duration of the ball drop. Each point represents one interception attempt. To the left an example of a pretest, to the right an example of the posttest (of the Breakout-EMG group).