Performance-enhancing Paralympic technology raises hopes and concerns
When South African runner Oscar Pistorius stepped on the starting blocks at the 2008 Olympic qualifying race, the crowd exploded in heartfelt applause. For the first time, Pistorius, a double-amputee, was to compete against able-bodied athletes on specially designed carbon-fibre ’blades’. The race marked a turning point in the history of the Olympic Games and has since reignited the highly charged debate about using technology to improve athletic performance.
Science and engineering has in fact been at the heart of the Paralympic community since the games began at the Stoke Mandeville Hospital in Aylesbury. In 1948, neurologist Sir Ludwig Guttman started using sport as part of a rehabilitation programme for injured Second World War veterans. He set up a competition with other hospitals to coincide with the London Olympics that year and over the next decade injury units throughout Britain became involved in the games. Half a century later and the Paralympics have become an integral part of the Olympic legacy.
Paralympians, more than most other athletes, rely on technology to compete, and improvements in recent years have been rapid. Whether it is the design of a wheelchair or the materials used to reduce the weight of prosthetics, engineers are increasingly pushing the boundaries of what is acceptable. The influx of new technologies in the Paralympics is, however, a relatively new phenomenon. ’Even for some of the elite athletes, their equipment was poorly maintained, let alone optimised for performance,’ said David James, senior sports engineer at Sheffield Hallam University.
“In elite sport, if you’re not optimising equipment then someone else will”
DAVID JAMES, SHEFFIELD HALLAM
Yet as the Paralympics embrace innovation, some quarters of the sporting community have raised concerns about the introduction of performance-enhancing systems. Their argument is that engineering should help to provide a level playing field in sport rather than create an unfair advantage. After all, they claim, sport is about athletic ability over anything else. James disagrees: ’No matter what you think about the Olympic ethos as encompassing this friendly event, it is about winning… In elite sport, if you’re not optimising equipment then someone else will.’
In 2003, James and his team worked with Paralympic champion Dave Holding to optimise the design of his wheelchair for sprint racing. Using computational fluid dynamics (CFD), the researchers found aerodynamic inefficiencies behind the wheelchair and a wake effect caused by a gap between Holding’s shoulders. They calculated that if they optimised the design they could reduce drag by three per cent - equivalent to a reduction of 0.03 seconds over 100m. Further tests showed that reductions in the weight of the wheelchair would result in an additional improvement of 0.16 seconds over 100m.
’We started thinking: what if we put a mesh on the athlete’s trunk to stop the pressure difference between the front and the back of the chest? If you’ve ever seen wheelchair athletes pulling their T-shirt down over their knees, effectively that’s what they are trying to do,’ said James. ’We validated that if Holding had made these changes, he would have shaved off 0.2 seconds over 100m. That’s a lifetime; it separates the top five athletes in his field.’ According to James, this approach does have its critics who fear it could move the sport forward too rapidly. This sentiment is shared by those who believe the Olympics and the Paralympics have become contests for those who can afford the technology.
Simon Choppin, a sports engineer researcher at Sheffield Hallam, is aware that sports science needs to be regulated carefully. ’Whenever you have technology involved in sport, you immediately create a distance between the athlete and the event, and you have to be careful that the performance of that athlete isn’t too reliant on the equipment and cost of technology,’ he said. In the case of Paralympians, however, the case is more complicated. Their equipment is usually a part of who they are, rather than a separate apparatus used for sport. Is it right for regulators to prevent Paralympians from being the best they can? And why should a sport so reliant on technology not use it to promote interest?
These questions have been brought into the mainstream by Pistorius’s ambition to race in the Olympics alongside able-bodied athletes. The field of prosthetics has advanced dramatically and it is challenging the notion that Paralympians are at a disadvantage. No one in history has run a faster second half in a 400m Olympics race than in the first half, except for Pistorius who was two seconds faster in the final 200m of his race. In 2007, this raised concerns among the International Association of Athletics Federations (IAAF), who ran some tests on the athlete to try and understand the physical strains that Pistorius was undergoing compared with his competitors.
“You have to be careful the performance of the athlete isn’t too reliant on the equipment”
SIMON CHOPPIN, SHEFFIELD HALLAM
The IAAF was concerned that Pistorius’s carbon-fibre prosthesis, inspired by a cheetah’s rear leg, required less energy than a complete leg, had a longer stride pattern and did not release lactic acid into the althete’s bloodstream. The unique shape of the blade means that energy is moved to the front where it is released during push-off, creating a longer stride. Pistorius refutes this and argues that he has the same ratio of blood per muscle in his body as able-bodied athletes and therefore the same amount of lactic acid. Nevertheless, independent tests at Sheffield have shown that Pistorius uses 25 per cent less oxygen over 400m and therefore has an unequivocal advantage over able-bodied competitors.
Vicky Tolfrey, director of the Peter Harrison Centre for Disability Sport at Loughborough University, is concerned that allowing Pistorius to compete will change the competitive nature of the Olympics. ’If you start allowing an assisted device, you start opening the gates for different sports,’ she said. ’You could argue that wheelchair racers should be in with runners because they are still doing the same distance.’ But James argues that it’s not as simple as that. ’We create advantage for British cyclists and bobsleigh athletes using similar ideas,’ he said. ’So if you’re going to ban him, we should ban a lot of other things as well. It’s a bit of a Pandora’s box to be honest. While it’s true that the prosthetics are still fairly rudimentary, you can only imagine where these things might go in 100 years’ time.’
A new wave of active prosthesis is providing a glimpse of what might lie ahead. Prototypes of artificial body systems that have their own energy supply, such as powered ankle joints, have already been developed, raising the possibility that future athletes will be unconstrained by their biology. Within the next century, a league of disabled athletes who will outperform able-bodied competitors may well become reality. ’It’s a fascinating area and engineering has certainly shaped the sporting world,’ said James. ’I guess the question is: where do we want it to go in the future?’
A new class of biohybrid prostheses will enable quicker running time
Hugh Herr, director of the Biomechatronics Group at the MIT Media Lab, wants to create a prosthetic that could enable its user to run faster than Usain Bolt. He is pioneering research projects for a new class of biohybrid ’smart’ prostheses and believes the next century will blur the boundaries between man and machine.
One project involves a motorised ankle-foot prosthesis that provides active mechanical power. Its basic architecture is a unidirectional spring, configured in parallel with a force-controllable actuator that allows the ankle foot to match the size and weight of the human ankle.
Herr is now developing small, wireless implants that can be attached to muscles near the neuromuscular junction. In the longer term, he is researching the possibility of directly attaching a foot prosthesis to an amputee’s residual limb bone.