Over the last few years sport scientists have become increasingly interested in the application of speed, agility and quickness (SAQ) training to a variety of sports. Indeed a recent report in the Journal of Sport Science supports the efficacy of SAQ training, with results showing enhanced physical quickness in female football players⁽¹⁾.

Most football players, coaches and managers will agree that nothing worries defenders more than a quick, agile striker who is capable of outsprinting opponents. However, as strikers like Alan Shearer have proved, you don’t have to be the fastest sprinter to score goals. Some players seem to be in the right place at the right time, to sense what is happening a split-second before others and to react more quickly, thereby gaining a decisive advantage.

Two intriguing questions arise from such observations: first, are there reliable differences in speed and accuracy of decision-making between players of differing standards? For example, do the perceptual processes of experts and novices differ and, if so, how? Secondly, can players acquire mental quickness or anticipation through perceptual training, or is it simply a matter of experience?

Even spectators with little technical knowledge can easily identify a football player who seems to have an abundance of time on the ball and an ability to read the game, where others appear rushed and clumsy by comparison. The same can be said of a tennis player like Andre Agassi, who is generally regarded as one of the best service returners in the game. When on form, Agassi epitomises modern definitions of skill by consistently hitting effective returns with maximum efficiency, even when opponents like Greg Rusedski are firing down serves at almost 230kph.

In tennis, the ball has only around 24m to travel before it reaches the returner⁽²⁾, and when balls are travelling at such speeds it seems obvious that anticipation and the perception of important visual cues is vital. In fact, the evidence suggests that, for a ball served at 150kph, a responding player has only about half a second to determine the speed, direction and spin on the ball before organising and producing a response⁽³⁾. Similar demands exist in other fastball sports, such as cricket or squash.

At this point it would be helpful to explain how information is processed in humans. Not all researchers agree about how this happens, but the following example is based on the theories of Schmidt and Wrisberg⁽⁴⁾. I will describe the relatively simple skill of catching a ball to demonstrate this theory. A ball that is moving within an individual’s visual field is detected by the eyes, and information about this stimulus (ball) is transported from the receptors via sensory neurones (in this case the optic nerve) towards the central nervous system (consisting of the brain and spinal cord). It is here that the incoming information is processed, as the stimulus is identified by comparison with past experiences, allowing for a decision on the most appropriate response.

From brain to muscles

The selected response could involve moving the hands in a particular direction to intercept the ball. Once the movement sequence or motor programme has been selected, the motor neurones transport the relevant information to the muscular system, where information about the force and timing of muscular movements allows for an efficient response.

A number of problems can occur in this sequence of processing, leading to ineffective performance and an apparently uncoordinated response. At this point it is important to make a distinction between the reception and perception of information. Assuming an absence of visual impairment, when a ball is tossed towards two different individuals, both should receive the same sensory information. However, their ability to perceive the changing light waves that reflect the flight path of the ball, thus allowing them to anticipate where to move in order to intercept it, depends on past exposure to the same task and connections in the brain that link a particular stimulus to a response⁽⁴⁾. Whereas reception only involves the sense organs, perception is dependent on the involvement of the brain.

Quite clearly, the ability to accurately perceive or anticipate what is about to happen, and when, provides the sports performer with a distinct edge over his or her opponents. Two forms of information are needed to enable a fast-ball sports performer to anticipate the direction, force or type of response (ie shot selection) from an opponent⁽⁵⁾.

The power of prediction

The first is prior information, based on knowledge of how the opponent operates. For example, if a tennis opponent has only one type of serve you can predict with complete accuracy what serve is coming. Or if he/she serves to your backhand 95% of the time, there is a strong probability that the next serve will also be delivered to your backhand.

Thus, armed with this information, you may decide to anticipate and produce a quick sidestep just before your opponent makes contact with the ball, to allow you to play the shot with your stronger forehand groundstroke. However, if your opponent serves to your backhand only 60% of the time, anticipating the direction of serve is more difficult to predict with any certainty. Any anticipated response will be fraught with danger and the possibility of being deceived.

A second method of anticipation is based on your ability to selectively attend to and detect important pre-shot (advance) cues that specify the kinematics of the opponent’s stroke. In other words, just before a ball is struck cues are available about body positions, limb movements and racket head direction that allow you to predict the direction and force of response. In fact, there is greater research support for the theory of advance cue utilisation than for anticipatory responses based on probability⁽⁵⁾.

Perceptual experiments have used a technique called ‘occluded vision’ to test the hypothesis that experts will focus on different pre-event cues than novices in order to accurately anticipate what will occur. This technique involves presenting a participant with a series of images showing an opposing player performing a particular action, such as serving in tennis or bowling a cricket ball. The sequences are usually filmed from a position where the observing participant might realistically be located to increase the validity of the technique. Participants are shown sequences that are edited by halting the action just before contact, at the point of contact or just after contact with a ball or object. The participant is then asked to predict the direction and force of shot produced.

One such study, involving expert and novice squash players, required participants to predict both the direction (down the wall or cross court) and force (drop shot or drive) of an opponent’s stroke based upon viewing occluded film sequences⁽⁵⁾. Unsurprisingly, expert players were found to be superior to novices in the accuracy of their predictions. Analysis of directional errors revealed that the most critical times for extracting information about the stroke were just before contact with the ball and just afterwards when the ball was in flight.

When the responses of experts and novices were compared, it was found that both groups were capable of extracting information from post-contact ball flight cues, but only the experts could detect and use earlier cues. By means of a further manipulation (obscuring different body parts in the film sequences), the researchers provided evidence that this pre-contact information was extracted mainly by focusing on the opponents’ arm action. No differences were found between the experts and novices in terms of their ability to determine whether a drop shot or drive was going to be played.

In a similar study, differences between the visual search patterns of expert and novice performers were examined by studying the eye movements of tennis players attempting to identify whether a flat, top-spin or slice tennis serve was being produced⁽⁶⁾. Expert performers were found to be significantly more accurate in detecting the type of serve being produced.

When studying eye fixations, the researchers divided the tennis serve into three distinct phases:

1. The ritual phase – bouncing the ball and positioning the feet before action;
2. The preparatory phase, beginning with the elevation of the arm holding the ball and finishing when the ball reached its highest point;
3. The execution phase, starting with knee extension and ending with racket/ball contact.

They found that during the ritual phase experts focused on the shoulder and trunk region while novices concentrated more on the heads of their opponents. During the execution phase, experts concentrated more on the racket and holding arm than novices, who paid more attention to the ball. Experts apparently needed less information to identify the type of serve being produced and their speed of decisionmaking was quicker.

These results appear to suggest that, while the same information is available to expert and novice performers, experts are more effective at linking the information together to anticipate the type of serve being delivered. This evidence, together with examples from other sports,⁽⁷⁾ suggests that the standard coaching advice to ‘watch the ball’ may well be inappropriate when it comes to mounting a rapid response. Clearly, watching the ball during the preparatory and early execution stage of a tennis serve would cause the observer to miss important cues that could facilitate quicker reactions.

However, the researchers were quick to note that directing the attention of novice players to the aspects of performance being observed by experts will not be effective unless the novices are also taught to understand the links between the visual content of information and the related motor performance responses – eg what body positions or movements are related to a top-spin as opposed to a flat service.

A more recent study of tennis players also showed differences between experts and novices in speed of decision-making⁽⁸⁾. Participants viewed a life-sized model hitting forehand and backhand shots to four different court locations. Reaction time was measured by footpads (time between presentation of visual sequence and pressure on footpad) as the participants moved in the direction they thought the ball was going. Not only were the experts found to have faster reaction times but they were also found to focus on different sources of information. Again, experts focused more on shoulders, trunk and hips rather than the ball or the contact point. Thus it appears that the movements made by players when they are preparing to play a stroke can be a rich source of information that experts use to enable quicker responses.

Can anticipation be learned?

These findings are important in their own right, since they allow us to understand how it is that experts produce quick and accurate responses. However, the question that arises is whether or not it is possible to train non-expert performers to anticipate more quickly and with greater accuracy by means of perceptual training methods. Some evidence has emerged to suggest that accelerated learning of anticipation is possible, but results are not conclusive.

One recent study looked at the benefits of video-based perceptual training in relation to returning a tennis serve⁽²⁾. Pre- and post-test procedures involved participants standing in front of a large screen and responding to a video image of an Australian Institute of Sport tennis player performing 21 random serves (seven flat, seven top-spin and seven slice). Performance was measured by videotaped analysis of responses, and analysis showed that after eight 15-minute training sessions, speed of decision-making was significantly quicker than for a control group. However, no significant differences were found between the groups in terms of directional accuracy.

In a previous study⁽⁹⁾, four weeks of videobased occluded perceptual training, plus formal biomechanical instructions on the most important advance cues of relevant ground strokes, was shown to result in superior anticipatory performances. However, it is important to note that performance was measured in relation to a computer-based anticipatory task and not by oncourt performance. Nevertheless, more research on the effects of perceptual training in sports situations is emerging, and at least some benefits are evident.

Finally, how does mental agility training compare with its physical counterpart? One study compared the two techniques in tennis players of beginner-to-intermediate standard and found that the mental quickness group, who took part in perceptual training and received tips on how to link cues to subsequent actions, made faster decisions and predicted the type of serve more accurately than the physical agility group⁽¹⁰⁾. Apparently, mental quickness or anticipation can be just as vital as physical speed in some fast ball sports, and can buy you enough time to produce accurate responses.

In practical terms, what these findings mean to coaches and performers is that there is a need for selectivity in the cues attended to before contact in fast ball-type sports. One of the reasons players like Andre Agassi appear to have an abundance of time in situations where decisionmaking time is severely limited is that they anticipate what is going to happen by detecting and using important advance cues given out by their opponents.

Of course, at an advanced level players will train specifically with a view to minimising the movement discrepancies that distinguish different actions. And deception is most likely to occur when a performer has several response options in which movements begin in exactly the same way. For example, a tennis player who has three different serves and is able to produce these from the same preparatory sequence is likely to impair his opponents’ speed of processing, as it will take more time to distinguish the necessary cues that differentiate between serves.

In summary, studies on tennis players have established consistent information about the cues to which experts direct more attention during different phases of the tennis serve in order to respond more quickly. As more research helps to establish the important informative cues in other sports⁽⁷⁾, coaches may help to direct more inexperienced players to them and, more importantly, help them to establish learned connections between preparatory cues and response outcomes.

Lee Crust

References

1. Journal of Sports Sciences, 22, 191- 203, 2004
2. International Journal of Sport Psychology, 29, 231-242, 1998
3. Sports Coach, 12, 15-18, 1989
4. Motor Learning & Performance (3rd ed), Richard Schmidt & Craig Wrisberg, Human Kinetics, 2004
5. Journal of Sport Sciences, 8, 17-34, 1990
6. Journal of Sport & Exercise Psychology, 11, 382-398, 1989
7. Research Quarterly for Exercise & Sport, 69, 111-128, 1998
8. Research Quarterly for Exercise & Sport, 73, 107-112, 2002
9. Report to the Australian Sports Commission, 181, 1992
10. The Sport Psychologist, 8, 305-318, 1994