ABSTRACT
What is the main task of a player involved in an interceptive sport? Typically one has to hit a ball or a shuttle with a racket, a bat, a club or a stick to a certain location, for instance on the other side of a net. A naïve spectator usually just watches the ball and sees only whether the ball is on target, e.g. in or out of the court, and sometimes whether the ball has been struck fast or slow. Accuracy of the movement and its outcome has been the focus of attention of a large body of the movement science literature (e.g. Bootsma and Van Wieringen, 1990), and examples can be found in several chapters of this book. However, a good coach would also notice whether the player was relaxed or tense during performance.
