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07 Sep 2012 01:00
Jamaica’s Alphanso Cunninghan competes in the men’s javelin throw F52/53 in a chair held by special straps. Photo: Emilio Morenatti/AP
Oscar Pistorius's Flex-Foot Cheetah running blades, made by the global orthopaedic firm Ossur, always promised to be the most photographed piece of equipment at the Paralympics. And interest has only intensified following his loss to Alan Oliveira in the 200m and his angry complaint that the length of the Brazilian's blades should not have been permitted.
"In prosthetics, everything is open to interpretation," said Donna Fisher, of Ottobock, which makes blades for Germany's Heinrich Popow and Australia's Kelly Cartwright.
"The longer the blade, the longer the stride can be.
Pistorius argued that he "couldn't compete" with Oliveira's stride length, although analysis shows the South African took fewer strides.
The point of running blades, of course, is to replace an athlete's calves and feet. But what about their spiked shoes? Running spikes are difficult to attach to a smooth, hard carbon-fibre blade. So until February Pistorius had to spend hours scuffing his up and gluing on new spikes before each race. The balance was different each time.
To solve the problem, Nike, one of his sponsors, developed a detachable cushioned pad of spikes. Designer Tobie Hatfield spent months watching slow-motion footage of Pistorius running on a pressure-sensitive treadmill in Ossur's Iceland headquarters. Through this, he learned more about the ideal number of spikes (11) and where to put them. There is soft foam at the back of the pad, where Pistorius's stride begins, and a harder type at the front where it ends. Gluing time is now down to 15 minutes per leg.
Formula One wheelchairs
Although it is often seen as the equivalent of running, wheelchair-racing actually bears a stronger resemblance to Formula One.
The shape and structure of the chairs, the materials they are made from, the athletes' riding position, clothes, helmets and even the straps they use to hold themselves in place – all these things are constantly being scrutinised and improved.
"It's an evolution," said Dan Chambers, a designer at Draft Wheelchairs, which supplies the British team as well as some of its competitors. "Athletes like these get a new chair every year, so each time there is the chance to make small changes. In the past couple of years, a lot of work has been done to increase the stiffness of chairs. Flex is not wanted, because it misaligns the wheels, which makes them scrub on the track and lose energy."
Aerodynamic work is also important. Wheelchair racers have had their shapes scanned and analysed by computers and have even been blown about in wind tunnels – all to reduce drag. The results have helped them to select helmets and clothing and have strongly influenced their seating. "They've all been rotated forwards," Chambers explains, "which reduces their frontal area."
For these Games, the new chairs have a solid aluminium plate beneath the athletes' knees, which allows smoother air flow than the old cloth upholstery. Each competitor also has a bespoke welded seat gripping their lower body. "There is a chair that has been developed through all the wind-tunnel testing that is a nice, stiff light-carbon-fibre one," said Chambers. "But that's for the next Olympics."
Straps, stirrups and seatbelts
It is nearly impossible for disabled athletes to compete in the discus. Olympic throwers rely on nimble feet as well as upper-body strength to wind up, throw and then recover. Try sitting in a chair while throwing a discus and you will almost certainly fall over – and if you throw as hard as Derek Derenalagi, the former British soldier who lost his legs in a roadside bombing in Afghanistan five years ago, you will probably break a bone as well.
Paralympic rules allow competitors to use any chair or frame they want, as long as they can assemble and dismantle it within a certain time limit. Alison O'Riordan, Derenalagi's coach, was unhappy with his throwing frame, however, so she contacted the charity Remap, which builds customised equipment for disabled people.
A Remap engineer watched Derenalagi training and then designed an extremely strong but lightweight padded stool. Four straps secure it to the ground, two seatbelts hold Derenalagi on top and stirrups give his prosthetic feet purchase.
It is far from complicated, but it is precisely what Denelagi needs, holding his lower body in place while allowing the rest of him to move. "I can use what is left of my leg muscles and my core muscles to keep control and also to generate power," he said.
Crash, bounce, wallop
Equipment can get injured, too, especially in a sport like wheelchair basketball, where players travel at speed and are not supposed to collide but do. "They get absolutely smashed," said Michael Sheen, the design and engineering manager at RGK wheelchairs. "After a year, the chairs don't look like they did when they started, that's for sure." And, of course, if a chair breaks during a game it can be disastrous. The player can be substituted and the chair repaired, if that is possible, but often it is not.
As a result, design in this area focuses on the trade-off between strength and weight. Sheen has conducted a lot of stress analysis, using 3D simulations to determine the strongest frame and, after years of making titanium chairs, has switched to a high-grade aluminium model for these games. "It's much lighter," he said. "Essentially, that means it is easier to push. It also makes it a bit more responsive, so you can turn and manoeuvre better."
The unsinkable stool
Despite suffering from chronic regional pain syndrome, which makes it hard for her to stand or walk without a crutch, Britain's Danielle Brown is an exceptional archer. When she was 16, she defeated a field of able-bodied competitors at the national junior championships using just an adapted piece of old bicycle frame to prop her up.
As an adult, she approached Loughborough University's Sports Technology Institute to ask whether it could do better. It could. The trouble with the bike frame was that it lacked stability and had a tendency to sink into the mud. So Steve Carr and a team of engineers redesigned it with a broader base, wide feet, a locking setup and an alignment system to help her to find consistency in her position – even outdoors.
Within a week of using the new stool, Brown had beaten her personal best. The following week she broke the world record and subsequently broke it again to win gold at the 2008 Paralympics. In 2010 she became the first disabled athlete to represent England in a mainstream event, when she was part of the team that won gold at the 2010 Commonwealth Games in Delhi. – © Guardian News & Media
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