Running to success: The tracks of the 'Bird's Nest' National Stadium are reflected in a spectator's sunglasses during the 2008 Olympic games.
Credit: AFP
Once upon a time, the Olympics were simple. Ancient Greeks stripped naked then ran, threw things, and had a jolly time. No technology other than what Mother Nature gave you.
Today, of course many sports are technology driven. Just ask a cyclist. Or a swimmer in one of those water-repellent, full-body swimsuits that seem to be keeping half the field ahead of existing world records in any given Beijing final.
A lot of people presume that track and field, whose first Olympic events start this weekend, is simpler. After all, it's comprised of some very traditional events, going all the way back to those naked Ancient Greeks. But these days, running tracks are high-tech too. It's not just the featherweight go-fast shoes, or the perfectly balanced javelins. Even the track's surface itself is high-tech.
From cinders to rubber
When Britain's Roger Bannister first broke the four-minute mile in 1954, he did it on a gravelly cinder track. That might not be the oldest of technologies – grass predated it – but it's certainly one of the simplest.
Today's tracks are a far cry from the one used by Bannister: nearly as high-tech as the spectacular 'Bird's Nest' National Stadium China built to showcase the track in Beijing. And just like the new swimsuits, they can be designed to produce the fastest possible times.
A good track starts with a foundation to keep the whole thing from sinking into the ground. Over that goes a surface of rubber granules mixed with an artificial binder. Usually it's poured in place, but Mondo, the Italian company that built Beijing's Olympic track, believes it can get better quality control by making the track in a factory and unrolling it on site, in strips.
Still, all tracks – from the relatively cheap variety installed at neighbourhood recreation centres and playgrounds, to the multi-million-dollar type used at international sporting facilities – are made of rubber granules and binder.
"That's a synthetic running track in its simplest form, says Todd Grimes, vice-president for operations of Atlas Track Company, an organisation that designs and builds them, based in the U.S. city of Tualatin, Oregon.
Sometimes the rubber is comprised of ground-up tyres and the glue is asphalt. Sometimes the granules are virgin rubber made for the purpose, with polyurethane binder. Some of Atlas's tracks are even made from recycled, ground-up running shoes, collected by shoe giant Nike. Mondo, on the other hand, boasts that its Olympic tracks are made of natural rubber.
Mathematical model of running
All of these tracks still let runners use spikes like those worn by Bannister. That's because their surfaces are designed to be spike resistant. Spikes penetrate deeply enough to give traction, but the surface springs back, intact, afterward. That keeps the spikes from tearing up expensive tracks.
Any jogger who's tried out more than one or two tracks knows that there are tracks, and tracks. Some feel like running on concrete. Others are spongy. Jogging tracks tend to be soft, reducing the risk of injury. Competition tracks tend to be firmer. "Efficient but unyielding" says American masters racing champion Joanna Harper, of Portland, Oregon, who, in her early 50s, has been running track for 38 years.
The reason, Grimes explains, is that a soft track absorbs energy as it squishes under impact. "On a harder track, that energy is not absorbed. Thus, in theory, the athlete won't expend as much energy to go the same speed." But it isn't simply a case of firmer equals faster. There's a fine line – a sort of runner's 'Goldilocks zone' – between too soft and too hard.
Outdoor track firmness is regulated by the International Association of Athletics Federations (IAAF), which wants to makes sure that records set today are comparable to those of yesterday. But decades-old work by Thomas McMahon, an engineering professor (and acclaimed novelist) of Harvard University in Cambridge, Massachusetts, indicates that there might be room for improvement if people want track record times to start plummeting in a similar way to the swimming records.
In the 1970s, McMahon got to wonder how tracks could be designed to maximize the spring-like power of muscles, ligaments, and tendons. He and his colleagues watched runners on test tracks covered in materials ranging from wood to foam rubber. Then they created a mathematical model of running, based on such factors as how long the foot remained in contact with the ground, and how far the body travelled while it was there.
Tuned surface
Their results were complex, but what they found was that there is indeed a perfect springiness for track surfaces. Too much cushion in the track and it eats energy, just as described by Grimes. Too little, and you bounce off too fast, without giving the body's natural springs – those muscles, tendons, and ligaments – time to store and release the ideal amount of their own energy.
Armed with that information, McMahon and colleague Peter R. Greene designed a new "tuned" surface for Harvard University's Gordon Indoor Track and tennis facility, calculating that it should speed up runners by two to three per cent compared to the firmer surface they'd been used to.
The new tuned track was 220 yards (201 m) of wood topped by polyurethane. It worked. In its first season of use, from 1977 to 1978, McMahon compared how Harvard's runners fared on it, vs. the tracks they used for meets at Princeton and Cornell Universities.
He found that, even though away meets are championships where the Harvard runners should have been trying for peak form, the Harvard runners were 2.91 per cent faster at home. It wasn't just a home-field advantage. Runners from other schools were also faster at Harvard.
Since tuned wood tracks aren't weather resistant, there's been no big rush to build them outdoors, even if they did meet IAAF standards. But Harvard's and similar indoor facilities that McMahon helped design are still in use and show just how much difference a running surface can make.
When McMahon did his research, he predicted that a tuned surface for an outdoor track could improve performance times there by as much as they did indoors: about 3 per cent, or 7 seconds.
Record beating
By that time, races were being run on synthetic tracks, which first came into use in the early 1960s. Much better than the sometimes-muddy dirt and cinder tracks used in Bannister's era, these tracks had probably contributed substantially to the improvement of the one-mile record, then standing at 3 minutes 49.4 seconds, set by John Walker of New Zealand.
Today, the record is down to 3 minutes 43.13 seconds, set in 1999 by Hicham El Guerrou of Morocco. Racing fans blame much of that improvement on improvements in running shoes and training methods. But track manufacturers are perfectly aware of McMahon's work. Like Grimes, they're fully aware of the fine line between a track that's too firm and one that's too hard, and are always looking for the optimum performance zones within the limits set by the IAAF standards.
So as you watch the runners circle the Bird's Nest track in Beijing, realize that the lowly surface beneath their feet is part of what makes them fly.
Richard A. Lovett is a writer, and dedicated runner, based in Portland, Oregon. He is also a regular contributor to Cosmos.
