London 2012: Inside track on Olympic running surface
When events get under way at the London 2012 Games' main stadium, most people following the drama on the track might not be aware they are also seeing a cutting-edge piece of technology.
The track was designed and laid by Mondo, an Italian company that has provided all the tracks at the main Olympic stadiums since the 1992 Games in Barcelona.
Unlike other track designs that combine traction and shock-absorption in an upper layer of rubber granules, the Mondo track separates these functions, with a cushion backing for shock absorption and a solid upper layer that optimises slip resistance, traction and durability.
This design cuts the need for the spikes on athletes' running shoes to penetrate the running surface. Shoes used on tracks fitted by the Italian firm are considerably shorter and non-penetrating.
This means, the designers say, that less time and energy is lost going into the track and retracting the spikes afterwards.
Both the layers in the track are made of rubber, explains Joe Hoekstra, Mondo´s project manager for London 2012.
"The two layers are vulcanized, a process which cross links the molecular structure of the different materials and makes the surface more uniform, stronger and elastic," he tells the BBC.How the track works Continue reading the main story
The cushioning on the underside of the track used to be in the form of square netting, designed to be flexible in the running direction only.
However, since the Beijing Olympics in 2008, the design has changed and the backing now has elongated diamond shaped cells.
"The advantage of this design is that the cells flex easily in any direction, rather than just forwards, giving ideal cushioning while providing great material reaction time," Mr Hoekstra says.
Reaction time is a key concept. Fast reaction means the athlete gets their own energy back.
London 2012 - One extraordinary year
"The material comes back quickly enough to act like a springboard underfoot providing more energy return and assisting the athlete into the next stride," he observes.
At the same time, the multi-directional flex also shortens the so-called rolling time, when the athlete's foot naturally rolls, on impact, from the 5th metatarsus (outside portion of the foot) to the 1st metatarsus (inside portion of the foot).
This reduction in rolling time means the overall contact time of the foot with the track is shortened, and the foot spends less time on the ground.
At the other end of the spectrum, a spongy material would deliver high shock absorption, but the material would only recover long after the athlete has moved on, giving them no energy return at all.
"Some athletes say our track is not as soft as others, but softness does not always mean safety and better performance. A surface that yields too much will only produce fatigue, like running on sand," says Mr Hoestra.
Spike in sporting success
Since the 90s lightweight ceramic spikes have replaced the old steel ones.
2012 track properties
- Optimum traction
- Sloped slightly inwards for water run-off
- 120 tonnes of rubber were used for the London Olympic track, all pre-fabricated in Italy
"In the early 90s, when metal composites were first developed for the aerospace industry, companies like Omni-Lite began to see them as having commercial applications," says David Grant, chief executive of Omni-lite Industries.
The California-based company makes parts for the aerospace industry and holds the patent for ceramic spikes.
Since 1996, the firm has sold about 150 million of them.
"Considering there are typically between 12 and 14 spikes in a shoe, that would be approximately 10 million shoes," estimates Mr Grant.
One of the main advantages of the composite spike is that its weight is one third that of a steel spike.
The US firm has worked closely with the Italian track designers, he adds.
"We designed a spike to compress the track and hence the energy from that compression returns back to the athlete and is not absorbed by the track."
Since the development of the ceramic spike, the technology has reached the point where specialised spikes made for Olympic athletes are now made from "nano materials".
"Typically these are stronger and more wear resistant than the original lightweight spikes. These spikes were first utilised in Beijing and will be used in London," Mr Grants tells the BBC.
The Mondo-designed track at the London 2012 Olympic Stadium was tested by Labosport, one of the independent labs accredited with the International Association of Athletics Federations (IAAF).
Alastair Cox, director of Labosport, says that by setting track standards, the "IAAF wants to ensure first of all that a record broken in London is as valid as one broken in Beijing or Sydney".
He adds: "Secondly, they want to ensure that the surface is suitable for all the events that will take place in the stadium."
Mr Cox describes athletics as an unusual sport: "It is not one activity like football or cricket where you are playing one single game."
What would be an ideal surface for the 100 metres may not necessarily be so for the 10,000 metres.
"Crudely speaking, the old idea was that the harder the surface the faster the surface, so a sprinter would like to be running almost on concrete because it gives him the greatest assistance to run quickly," Mr Cox explains.
"But clearly, if you are a distance runner, running on a very hard solid surface has long-term implications from injury perspective."
Labosport has made sure the London 2012 track complied with the set standards for shock absorption and degree of deformation.
The lab uses machines known as artificial athletes, which are basically mechanical simulations of the loading pattern of an athlete running on the surface.
Another key measurement, Mr Cox reveals, is friction.
"We make sure it is not going to be too slippery when it is wet, but equally we need to ensure that friction is not too high and there is too much grip," he tells the BBC.
Apart from the main nine-lane 400-metre track, Mondo has also laid an 80-metre "final-call" sprint straight under the main stand, and a 400-metre warm-up track, identical to the competition one.
For athletes, experiencing the track is key, according to Joe Hoekstra.
"Athletes need to consider the number and length of the spikes in relation, for example, to body weight, prevalent conditions (wet surfaces require more assistance in traction) and type of event," he says.
"In general, field events like high jump and javelin require more traction, so the ideal shoes for these events have more spikes and they are longer".
Shorter spikes minimise shock from the track for long distance athletes.
But Mr Hoekstra acknowledges that, ultimately, it comes down to personal preferences.
He says: "In the same way a Formula One driver would not race without getting to know the track and choosing appropriate tyres, getting to know the track and choosing the right shoes for track and event is crucial."
After years of research and innovation, the stage is now set and ready to come alive with the magic of human endeavour.