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Expanded web feature: Winning the World Cup

Science reveals there is much more to the beautiful game

Summer 2010

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On 11 July the Jules Rimet trophy will be clasped in the hands of the winning captain and the parties and parades will just be beginning for the World Cup holders.

Victory is achieved by a combination of individual skill and athletic prowess, tactical teamwork, and gritty determination. Even taking luck into account, knowledge is power, and science can play a part strengthening all of these cards into a winning hand.

Can players improve their reactions and ball-reading skills? Do 'isotonic' sports drinks really work and could the type of grass really make a difference? Read on for a playful digest of how BBSRC-funded science helps us understand what's happening on and off the pitch (see 'Football facts'). NB. Offside rule not included.

Ball control

Throughout a game of football, players kick, throw and head the ball with remarkably consistent precision. They also perform these actions whilst running, or time their runs to manoeuvre their bodies to take advantage of the smallest windows of opportunity. What lies behind such spectacular motor control?

"Kicking a ball is a whole-body motion and the brain needs to coordinate most of the 640 muscles in the human body," says Dr Jörn Diedrichsen at the Institute of Cognitive Neuroscience, UCL. "The problem the brain has is an engineering nightmare. However, in the moment they contact the ball with the foot, they achieve an astonishing precision."

He uses optimal feedback control theory to explain the coordination that involves multiple muscles, joints or limbs (effectors). Based on experimental data, the model makes quantitative predictions about the distribution of energetic work across multiple effectors (ref 1).

"Optimal feedback control theory provides a description of what would be the best thing to do in this situation. It predicts that the brain should only fight the variability that interferes with the goal," he says.

When a ball is thrown or kicked the motion of every muscle, joint and tendon is slightly different each time - exact repetitions are impossible - yet with intense and long practise incredible accuracy can be achieved in different conditions, like when it is windy for example.

Diedrichsen says research on such motor decisions has revealed that our motor system is very good at quickly calculating the risks and benefits and making a decision on the fly.

"They call it success with variability," says Dr Andrew Spence of the Royal Veterinary College Structure and Motion Laboratory, who like Diedrichsen receives BBSRC funding to investigate the biomechanics of locomotion. "Your nervous system knows what you're trying to do, and saves energy and control effort by only rejecting noise from muscles and neurons and the outside world that get in the way of the objective." He adds that although more studies have covered throwing, kicking would probably be similar.

World in motion

To kick or head a ball the player has first to perceive it and react. Dr Andrew Welchman, a BBSRC David Phillips Fellow at the University of Birmingham's School of Psychology, has been examining the mechanisms underlying our perception of time and synchronisation of movements.

Welchman's lab has carried out 'laboratory gunfights' to show that we move 10% faster (about 21ms) when we react to something in our environment than we do when we initiate the action ourselves (ref 2).

Could this mean that a defender tracking an attacker's run might be better off waiting for the striker to make his move before tackling, lest the wily forward reacts quicker and avoids the tackle? Unfortunately, it's not that simple. "We've shown reacting is slightly quicker, but in the context of football it's not the way you want to test it," says Welchman.

It all comes down to choices. A defender has more options against an attacking run than to just 'draw and shoot' as in a Western shoot-out, and Welchman thinks that these extra variables are enough to warn defenders off not making the decisive move. "I wouldn't like to extrapolate from our study into a choices scenario as the brain mechanisms involved may well be different."

Welchman's previous research provides insights as to why sports men and women gain so much from practise. Working with colleagues at the Max Planck Institute in Tuebingen, Germany, he has found that the information used to estimate the likely trajectory of fast moving objects, like a ball, is biased by the brain's assumption that the world generally doesn't move very fast.

In our field of vision, this bias affects the way we perceive and interpret objects approaching from dead ahead far more than objects moving side-to-side. As a consequence you can misperceive the approach angle of something coming towards you (ref 3).

"One hypothesis is that your brain works out a 3D reconstruction from which you can extrapolate the ball's motion, like Hawkeye (the tennis and cricket ball motion predictor)," says Welchman. "But our study says that the brain doesn't do that. It reacts moment by moment as the ball comes towards you."

Welchman cites footage of goalkeepers from behind the net as an example. "You can see they are tracking, tracking, tracking and only at the last moment do they try to make a decision about where the ball is going to go."

So there exists a trade-off between the certainty of where object going to go and time it takes to get your body there. "That's something the expert footballers have to trade off," says Welchman. "Footballers spend a long amount of time training themselves, and so they have a set of expert ways of doing things that help them work out what their limitations are and how to overcome them."

The science of success

Sporting success is not just for the history books (see 'BBSRC for team GB'). The winning 'feel-good' factor can have a major impact on a country's economy and mood, and the evidence is certainly there that science can improve sporting performance, according to Dr Gladys Pearson at the Department of Exercise and Sport Science at Manchester Metropolitan University.

In football, she cites the use of tracking and movement analysis software which helps the coach illustrate to the team what they did and didn't do well, and how to improve next time. "There are scientists in our department dedicated to maximising the information one can gain from such image analyses," she says.

In work funded by BBSRC, Pearson has investigated nutritional supplements to help performance from a prolonged period of inactivity, such as after end of season periods, and the so-called 'isotonic' drinks that players can be seen guzzling during breaks in play.

"It is well established that the ingestion of carbohydrate-containing drinks can improve the performance of same-day prolonged exercise over and above no-drink or drinking only water," says Pearson. The secret to improving performance further could be in adding proteins. Pearson's work saw a marked benefit for older persons who utilised carbohydrate drinks during exercise and amino acid (protein) cocktails after exercise (ref 4).

"Combining proteins to a carbohydrate rich drink, in a chocolate milk drink for example, is far superior to drinking either a carbohydrate- or fluid-replacement drink," says Pearson. "This cocktail is better at increasing the duration of exercise and helping with the rate of recovery, even if the calorific content of the drinks is matched." The work also illustrates that sports science research can lead to improvements in healthy living way past our more competitive years.

Turf wars

Not all football pitches are the same. On African pitches, a native grass called kikuyu, Pennisetum clandestinum, is ideally adapted to local conditions and used because of its hard-wearing properties. But this warm season grass goes dormant in winter when the World Cup is due to be played, South Africa being in the southern hemisphere.

Facing the prospect of yellowing pitches being broadcast to millions around the globe, FIFA officials decided to overseed the kikuyu grass with a perennial ryegrass commonly used in temperate Northern Europe.

"Perennial ryegrass has a bright green colour and can tolerate the colder conditions and that's what they will be using for the World Cup, supplied by a Danish seed company," says Dr Daniel Thorogood of the Institute of Biological, Environmental and Rural Sciences (IBERS, a BBSRC institute) at Aberystwyth University. "They will shave off the surface of the old kikuyu, now yellow and dormant, and overseed it with the cool season perennial ryegrass and together they will make up a durable playing surface."

There have been whispers that using cool season ryegrass favours the European nations, and that the switch from pure kikuyu will be a disadvantage to the African teams who are used to its bounce. But Thorogood, who completed his PhD on the genetics of self-incompatibility in perennial ryegrass (some of varieties he developed at IBERS have been used on the Wimbledon tennis courts) says the controversy is overblown. "Overseeding is commonly done and something they would do annually as a matter of routine pitch management in the tropics and sub-tropics," he says.

Pitch management is principally concerned with influencing the trade-off between the cutting height and the playing quality of the surface. If the cutting height is too high, then as the blades get taller a smaller number of larger shoots are produced and the grass becomes less dense. "It's an overriding ecological principle - the 3/2 self-thinning rule - and you get the same thing on a bigger scale in a forest," says Thorogood who adds that 2cm is a commonly recommended cutting height. "Anything lower compromises biomass, hence wear tolerance, and anything higher compromises the playability of the surface."

Grasses share a common genome architecture, and what we learn from ornamental or functional turf species can often be translated into other crop species. "We might one day be able to transfer genes in perennial grasses to annual cereals to create environmentally more sustainable perennial cereal crops," says Thorogood.

BBSRC for team GB

As the 2010 World Cup passes, eyes will be on the London 2012 Olympics as one of the next major global sporting events. To promote research relevant to athletics, BBSRC is collaborating with UK Sport, the lead Government organisation responsible for the strategic support and development of high performance sport in the UK.

Research will be focussed on 4 areas - neurological changes in the acquisition of skill, stress resilience, efficiency of muscle performance, and optimising training portfolios - where biology could be applied to sport-related disciplines and, by using sport as a model system, knowledge fed back to biology.

Dr Scott Drawer, Head of Research and Innovation at UK Sport, says they are constantly looking for new ways in which our athletes can improve the way they train, recover and perform. "At UK Sport we have a well established Innovation Partnership Network from the best of British industry and academia, and we are delighted to be exploring this possibility with the BBSRC and their research community."

With your hand on your heart... © Arran Frood

Football facts

• Since 1947, English teams wearing red shirts have been domestic league champions more often than statistically expected (ref 5)
• The red-shirt effect is also seen in judo (ref 6), but to complicate matters, a colour effect exists in other sports where red is not even worn (ref 7)
• Penalty takers wearing red in a study were perceived to possess greater scoring ability than those wearing white (ref 8)
• Portugal's Cristiano Ronaldo 85% likely to kick to the right hand side of the goalkeeper if he stops in the run up to the ball. (ref 9)
• In close games, referees have been found to favour the home side by allowing more injury time at the end of normal play (ref 10)
• It pays to play with both feet: footballers in the 5 major European leagues earn more for their nimble ambidextrous 2-footedness (ref 11)

References

1. The coordination of movement: optimal feedback control and beyond (external link)
2. The quick and the dead: when reaction beats intention (2010) (external link)
3. Bayesian motion estimation accounts for a surprising bias in 3D vision (external link)
4. Influences of carbohydrate plus amino acid supplementation on differing exercise intensity adaptations in older persons: skeletal muscle and endocrine responses (external link)
5. Red shirt colour is associated with long-term team success in English fotball (external link, PDF)
6. Psychology: Red enhances human performance in contests (external link)
7. Sporting contests: Seeing red? Putting sportswear in context (external link)
8. Soccer penalty takers' uniform colour and pre-penalty kick gaze affect the impressions formed of them by opposing goalkeepers (external link)
9. England’s chances of World Cup glory (external link)
10. Favoritism uder scial pessure (external link)
11. The returns to scarce talent: footedness and player remuneration in European soccer (external link, PDF)

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