The Secret to Saving a Penalty Kick

Is saving a penalty kick in soccer really as hard as it seems? Statistics show that saving a penalty kick is one of the hardest challenges in any sport. In the World Cup, a major international soccer tournament that takes place every four years, goalkeepers correctly predict the direction penalty kicks will be shot 57% of the time, but only save 22% of the shots, according to ESPN’s Sports Science. Now, scientists are using technology to teach goalkeepers to read certain movements that a shooter makes. This will help goalkeepers make a more accurate prediction to which way the player will place their shot.

“A soccer goal has 192 square feet. It takes a goalie about 730 milliseconds to reach a ball at the post. A ball shot at 70 miles per hour from 39 feet away can reach the top corner of a goal in 400 milliseconds. This means the goalie has to make an assumption of where the ball will be kicked before the player makes contact with the ball. To do this, the goalie must observe every movement the shooter makes. If they wait until the ball is kicked it will be impossible to stop the ball, both physically and mathematically,” says ESPN’s Sports Science.

According to experimental psychologist Marc Green of visualexpert.com, human reaction time is too complicated to have one exact number that could be used as the average. It has a large range because there are many variables that create the reaction time in any event.

 According to Rockwood Summit's varsity soccer goalkeeper, sophomore Sean Clancy, age 16, “First determine which foot they will be kicking the ball with. If they are a right footed kicker and the inside of their knee is open to the goalie, they are most likely to kick to the right side of the goal. When their knee is closed, they are more likely to kick towards the left side.”

Sophomore, Jake Leeker, age 15, another Summit varsity soccer goalie, says watch the direction of the shooter's arms. “If a right footed kicker lifts their left arm, the shot will usually go right,” he adds, “If their left arm stays at their side, the shot will usually go left.”

Gabriel J. Diaz, doctoral student at Rensselaer Polytechnic Institute, analyzed a player shooting a penalty kick using motion capture technology and a computer. To get the data he placed 40 electronic markers on the major joints of the body. The markers showed each movement made by every joint. He examined 63 shots to the left and 63 to the right. After reviewing the shots, Diaz could predict which direction the shot would go before the player actually shot the ball.

Goalies need to study the motions of the player on computers so that they can learn to improve their reading of movements the shooter makes. Each movement a shooter makes gives away information to the goalie. Goalies must find a way to make significant use to these movements.

            Clancy agrees that this technology is beneficial to the goalkeepers. However, he says, “When a goalie makes their decision, they should stick with their instincts.”

More studies are being done with the motion capture technology so that it can be put to a greater use. Training routines are going to be developed based on the motions captured in the experiments. The goal is to help goalies train more efficiently by the next World Cup in 2014.

            With this technology, researchers believe that a goalie will have more time to react to a penalty kick. “The best performers wait the longest before responding,” says Diaz. With this technology, the hardest challenge in sports is going to eventually progress into a simpler task.