In the following part, several common skills that are used in table tennis will be contrasted, including hand-eye coordination, forehand stroke, backhand stroke, and the serve stroke.
2.1.5.1 Hand-eye coordination
Table tennis is a prototypical sport in which players have to decide what movement to perform and how to carry out the movement within a very short time. Therefore, it helps to develop hand-eye coordination, agility and reflexes and can contribute to general fitness. It has to capture a large number of lifetime participants. Table tennis meets all the criteria, and that is why it is the most played racket sport in the world for young and old people (Kondric et al., 2000; Mueller & Gibbs, 2007; Raab, Masters, & Maxwell, 2005).
There are three facets of the activity of table tennis players that improve our understanding of everyday actions: initiative taking in interaction situations, exploration and disguise as components of play, and the innovative as well as conservative nature of the activity (Sève et al., 2002).
For instance, Rodrigues, Vickers, and Williams (2002) studied how players coordinate head, eye and arm movements to acquire the necessary visual information for successful performance of a table tennis task. They wanted to determine whether head, eye and arm coordination varies as a function of expertise and temporal constraint. They reported that the players were able to accommodate the constraints imposed by the early cue-condition by using shorter quiet eye duration, and earlier quiet eye offset and reduced arm velocity at contact. Finally, they found that cue-condition, modifications of gaze, head and arm movements were not sufficient to preserve accuracy. Therefore, their results focused on the functional coupling between perception and action during time constrained, goal directed actions.
2.1.5.2 Forehand stroke in table tennis
One of the most important strokes in table tennis is the forehand or forehand counter (for example, see figure 7). From the ready position, players should try to have their upper arm near their side with their elbow bent at a 90° angle. When your opponent strikes the ball, you begin your backswing. From the ready position, let your arm relax to a position below the height of the ball and, at the same time, twist your waist so that your racket (paddle) arm moves away from the ball and put your weight on your back leg. The back leg is the one farthest from the table (www.specialolympics.org).
Preparation Phase Backswing
Forward swing Follow-through
Figure 7. The performance phases of the forehand stroke in table tennis
However, the open stance forehand was once believed to be poor technique. Table tennis instruction experts are now advocating it. The studies of the open and square tennis forehand have been limited to the kinematics of the strokes and tend to show non-significant trends in racket, and ball rebound velocity advantages over the traditional square stance technique (Bahamonde & Knudson, 2003).
In striking skills in table tennis, the fastball should be observed, because the ball might lead one to believe that this is an easy task, but this task makes high temporal demands. Although these tasks require a short time to deal with, the players must strike the ball with a suitable velocity and good orientation (Marinovic et al., 2004).
2.1.5.3 Backhand stroke in table tennis
Although most players have very strong forehand strokes, proper backhand technique is essential. If the ball is coming to the left side of your body, you should prepare for a backhand stroke (for example see figure 8). From the ready position, the stance at the beginning of a stroke, twist the upper body so that your racket (paddle) moves away from the ball, and bring your racket (paddle) back and slightly down to the left of your stomach (www.specialolympics.org).
Preparation Phase Backswing Follow-Through Forward swing
Figure 8. The Performance phases of the backhand stroke in table tennis
Research on the one-handed backhand stroke shows that this condition may be related to the use of faulty stroke mechanics by novice players. Skilled players influence the ball with a hyper-extended wrist and extend the hand through impact. That is, the extensor muscles about the wrist joint act concentrically to develop racket speed through impact (Elliott, 2006).
In table tennis, a distinction can be made between two attractor states of the striking coordinative action, namely (i.e. the forehand and backhand drive). A player delivering the ball to different spatial locations across the table would force his/her opponent (particularly if the position to the table is constrained) at some point in time to shift from a forehand to a backhand regime (Sorensen et al., 2001).
Therefore, the forehand and backhand strokes are the fundamental rallying strokes in table tennis. A key to success in table tennis is developing consistency with one’s shots. This is done through working on proper stroke technique and improving concentration.
To sum up, backhand and forehand strokes are the two basic strokes in table tennis. Both strokes are accomplished by the activation of complex sequences of muscle activity which incorporate smooth coordination patterns of the trunk and lower extremities (Mavvidis, Koronas, Riganas, & Metaxas, 2005).
2.1.5.4 The serve stroke in table tennis
Several studies have focused on the kinematics of the tennis service. The importance of service speed is shown by its role in determining match outcomes and different training concepts to improve service performance (Ferrauti & Bastiaens, 2007).
In the table tennis serve, the ball flight time is approximately 800 ms, during which time the opponent must select an appropriate trajectory for the racket based on information available early in ball flight. Visual information from late ball flight may also help players to refine their estimates of ball position and velocity (Rodrigues et al., 2002).
Service usually takes from one to a few seconds to complete; however, there are many observations an umpire needs to take in order to make a judgment before or soon after the service stroke is completed. For instance, Wong (2007) aimed to develop an intelligent system which was able to evaluate table tennis services independently and aid the umpire to make a more accurate decision. He believed that the employment of videography, image processing and artificial intelligence technologies could help him in evaluating the service. He
expected to be able to track the location of the ball from live video images and evaluate the service according to the service rules. He found a system that might benefit players who want to have their services evaluated in real time without the need to have a human umpire present.
In fact, several tennis-coaching experts have advanced the use of complex training with light and heavy loads. These aim to immediately increase the serve velocity and therefore combine technical skill development with the training of overhead power and throwing performance (Ferrauti & Bastiaens, 2007).
Altogether, in most table tennis strokes, the stretch-shorten cycle is characterized by eccentric followed by concentric contractions. There are two important points in the service stroke as follows: (I) external upper arm rotation at the shoulder during the backswing slowed by eccentric contraction of the internal rotators at the shoulder. (II) concentric contraction of the shoulder internal rotators, in the drive to the ball is then slowed by an eccentric contraction of the shoulder external rotators during the follow through (Elliott, 2006).