Figure 2. . Each participant completed five directional runs while swinging and “hitting” an imaginary ball at the following points: the intersection between the forecourt baseline and the forecourt singles side line with a forehand groundstroke (a); the intersection between the forecourt service line and the forecourt singles side line with a forehand volley (b); the intersection between the service line and the centerline with a touch of the racquet on the court (c); the intersection between the backcourt service line and the backcourt singles side line with a backhand volley (d); and the intersection between the backcourt baseline and the backcourt singles side line with a backhand groundstroke (e). At the end of each run, the participant returned to the start box (30 cm × 30 cm), located on the center of the base line. Two video cameras were setup for continuous video recording and were focused on the backhand groundstroke at position e.