Studying the science of soccer

PARIS: Once upon a time, football was a simple game in which the players worked up a sweat, the cure to injuries was a magic sponge and taking a penalty was a matter of hoofing a ball with your cork-studded boot.

No more.

At top level today, the 11 men on the pitch are supported by a ghost army of people in lab coats. Physics, computer simulation, aerodynamics, biomechanics, nutrition and psychology are just a few of the disciplines that underpin the modern game.

Indeed, the business has become so big that every four years a World Congress on Science and Football is held.

The last confab, which took place in Antalya, Turkey, in January 2007, ranged over issues from seasonal alterations in the composition of a player's body to lab tests on the effectiveness of sports drinks and "curved running", or how to run faster thanks to more efficient locomotion.

Here is a roundup of some of the latest work in the science of soccer:

READ MY HIPS: Eighty percent of penalties result in a score. But scientists at John Moores University in Liverpool have found a way to help goalkeepers get more of an edge - to look at the position of the striker's hips just before the strike.

If the taker's hips are square-on to the goalie in a right-footed kicker, the ball goes to the right-hand side of the keeper. If the hips are more "open", or angled away from the keeper, the ball tends to go his left.

On the other hand, biomechanics also show the goalie's weak spot. If the keeper stays on his line in accordance with the rules, 28 percent of the goal is an unsaveable zone that guarantees a score provided the ball is kicked accurately and with sufficient force.

SEEING RED: Bet on Turkey this year but don't put your money on Sweden, the Netherlands or Romania, at least if colors are any guide. Experts from Britain's Durham University and Plymouth University found that soccer teams with red team strips, such as Manchester United, Liverpool and Arsenal, were the most successful, while those wearing yellow or orange were the least. The theory is that in nature, red is a testosterone-driven sign of male aggression, and this is picked up subconsciously by the opposition.

SPIN DOCTORS: Using high-speed cameras and powerful computer programs, physicists have unravelled the secrets behind the swerving free kicks made famous by Brazil's Roberto Carlos and England's David Beckham. The velocity of the ball, its spin and the drag of the air are the big factors.

Just after a kick, a spinning ball moves forward at relatively high velocity, and the air flows irregularly over it.

But when the ball slows down - specifically, when it reaches between 8m and 10m per second (30-37 kph per hour), depending on its surface structure and texture, the airflow becomes smooth, or "laminar", which instantly increases the drag, or braking affect of the air.

In a fraction of a second, drag can be increased by 150 percent. This drastically brakes the forward movement of the ball and enhances a curving movement, derived from the ball's spin.

So the result is a ball that, initially, dips to the side or above a defensive wall and then suddenly curves into the net. If you want to impress your friends, just quote the Magnus Force and the Bernoulli Principle, which result in FD = CDrAv2/2.

MATERIAL WORLD: Leaping out of the lab and onto the pitch are "intelligent" gloves and shinpads designed to ease some of the shocks of soccer. The gear is made of novel synthetic material whose molecules are free-flowing in normal circumstances, which allows the textile to be soft and malleable. On impact, though, the molecules form a cross lattice with each other, transforming the material into a stiff state and absorbing energy from the impact, and then returning to their normal state. The British firm d30 (d3olab.com) says its products take just 10 milliseconds to respond to the armor-plating trick and reduce the the force delivered to a player's shin by up to 70 percent.

ISOTONIC, NOT VODKA AND TONIC: Carbohydrates are essential for swiftly replenishing the energy in the fast-response muscle fibers in footballers' legs. Experiments (www.labnews.co.uk/feature_archive.php/1091/5/the-science-of-football) have shown that between 34 and 39 centiliters (12 to 14 fluid ounces) of drink contained 30 grams (one ounce) of glucose usually does the trick. Players should drink this dose 10-15 minutes before a 90-minute match, with the same amount at halftime. After the game, there should be no booze-up, but an isotonic drink to rehydrate the body and replace precious lost salts. A recent discovery, though, is that fresh cherry juice could be even more effective.

THE RIGHT TRACK: Motion sensors, image-processing algorithms, 3-D analysis and heart-rate monitors have replaced the coach's instinct when it comes to assess how far a player runs, his successful passes, shots and tackles and areas of coverage. According to Sport Universal Process (www.football-business.net/tracking-device.html), which analyzes more than 3,500 games per season, the most physiologically demanding flight in European football is France's Ligue 1. In a 90-minute game, a player in this division will run 10.5km and sprint 451m on average.

TRIUMPHANT TUBER: Nutritionists are commonly on the payroll of top clubs, in the light of evidence about the need to provide muscle stores with long-term energy to reduce fatigue and injury risk, especially in the game's second half. Arsenal manager Arsene Wenger famously kicked fish and chips and ice cream off the dinner menu after he came to the club in 1996. Fish, chicken and fresh vegetables, supplemented by lots of water, came in. Potatoes, rich in glucides and vitamins, are a nutritionist's favorite - a small plate of boiled spuds should be eaten three hours before a match, say some.

MIND GAMES: Another shadowy figure is the psychologist, a key figure in ensuring players and coach are relaxed, confident and motivated. At a penalty shootout, for instance, players get an important boost from sensing team support. Those waiting their turn are told to "bond" physically, with arms around each other's shoulders. Another technique is called framing, or getting worried players to focus on specific tasks. At halftime in the 2005 European Champions League final, with his team 3-0 down against AC Milan, Liverpool manager Rafa Benitez told his players to "go out and score the first goal and see what happens from there". Says sports psychologist Jim Petruzzi (www.pponline.co.uk/encyc/football-coaching-half-time-psychology), "If he had said 'go out and score three goals' the size of the task may have been too great."

Agencies

(China Daily 06/06/2008 page23)