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Tennis Vision: Are You Really Seeing the Ball?

May 25, 2005 01:15 PM

By Jim Brown, Ph.D., author, Tennis: Steps to Success -3rd Edition (Human Kinetics Publishers)

We have known how to record physical movements on film for more than a century. There have been ways to record eye movement since the 1960s. But only recently has there been a method of recording physical movement and eye movement simultaneously.

Joan Vickers, Ph.D., a professor in the Faculty of Kinesiology at the University of Calgary, has taken that technology and applied it to sports vision and performance. In a series of studies, Vickers and her colleagues are analyzing the results of high-speed cameras to help tennis players, volleyball players, and other athletes improve their skills through a "vision-in-action" training program.

A player is fitted with a two-camera, eye-tracking helmet (one camera viewing the scene, the other following eye movement), while a third camera records every move made by the athlete. In tennis, for example, the investigator can determine if the service receiver is looking at the ball, when he or she is looking at it, and what that person's body is doing before and during the action. Those elements are then locked together in time and put on a videotape. What Vickers is learning could change the way sports training is conducted.

"Elite players in volleyball," says Vickers, "receive the serve and get the ball to the setter 63 percent of the time. We found a male player who had a 64 percent rating and recorded his eye movements. Then we looked at the eye movements of Team Canada (men’s team), identified those who were not tracking the ball as well, and established a relationship between poor tracking and less skilled performance on receiving and passing."

Perpetual Motion a Problem
"Players who were having the most problems (including those in tennis) were in perpetual motion," continues Vickers. "They were too active. The world-class volleyball player would stand and watch the ball almost 400 milliseconds before moving. Before he took his first step, he knew what the ball was doing. We also found that lesser players tracked the ball for shorter periods of time. What is really interesting is that there were no significant differences in terms of other physical abilities between the elite player and those at a slightly lower level. The difference in performance was in perception, tracking, and attention."

"We also pre-tested athletes, put them through a six-week training program, followed them for three years, and compared their skills to eight equally-matched players. Those who had been trained with the vision-in-action system averaged more than 70 percent on the skill, almost ten percent higher than the control group."

Several drills have been developed to enhance "gaze behavior," as this process is also called. In one of them, volleyball players were asked to receive balls marked with a number and to call out the number. Then a letter was added to the number and players had to recognize both. Next, a barrier was placed between the server and the receiver so that the receiver couldn't see the ball until it was well out of the server's hand. Finally, the receivers began the drill with their backs to the server, then had to turn, call out the number and letter before receiving the ball and passing it to the setter. This kind of drill could easily be designed to fit tennis.

"This unlocks tremendous potential," says Vickers. "We just finished a basketball study in which free-throw shooters improved accuracy 13 percent in practice and two percent in games. Now, we are looking at tennis players, hockey players, table tennis players, and athletes in other sports. There is no reason why the vision-in-action principle won't apply to all of them."

Vickers says that athletes are amazed when they learn that they are not keeping their eyes on the ball. Players and their coaches can see the results because the videotapes are personalized. Some athletes even change technique (without coaching) as a result of improved focusing or tracking ability. The system shows them a side of performance they've never seen before.

The next steps are for the Vickers research team to continue testing individual athletes, to validate the results of vision training in other sports, and to develop sport-specific training videos that would be available to athletes everywhere.

© 2005 HMS Publishing, Inc.
Jim Brown will be contributing new content to this site on a monthly basis. If you have a question for Dr. Brown please feel free to email him at
sportsmed@mindspring.com.

 

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