WHEN Bryan Kirkland sees middle-distance wheelchair racers sweating and shaking on the starting line, he knows it is not necessarily a sign of nerves. Kirkland, a retired member of the US Paralympics team with several medals to his name, says such behaviour is a classic sign of “boosting”, a method of enhancing performance that can mean the difference between defeat and victory. The trouble is, athletes who turn to boosting also tread a line between life and death.
Now one spinal cord researcher is calling for a change in rules to stamp out the practice which, while banned by the International Paralympic Committee (IPC), remains difficult to test for.
In the vast and inventive world of doping, boosting is unique. People with a spinal injury at the T5 vertebra or higher – around the level of the shoulder blades – typically lose brain control of their cardiovascular system as well as their limbs. Without communication between the brainstem and the cardiovascular system, their bodies do not respond to exercise: heart rate, blood pressure and oxygen uptake do not rise during workouts. Their athletic performance suffers.
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Boosting allows athletes to overcoming this disadvantage. By intentionally breaking a toe, sitting on their scrotum, or blocking their catheter, a paralysed athlete can kick-start their body’s reaction to stress. Although the athlete will not feel the pain, blood pressure and heart rate will still rise. Their performance will improve.
There is no question that boosting works. In middle-distance wheelchair racing, it can shave nearly 10 per cent off race times (Clinical Journal of Sport Medicine, vol 4, p 1). And, although estimates of its prevalence vary, it is not uncommon, says Kirkland, who has never used the technique.
But the sweating and shaking associated with boosting also indicates the onset of a medical emergency. Under normal circumstances, the rise in blood pressure following a painful experience is regulated by the moderating influence of the brainstem. With a spinal injury at the T5 vertebra or higher, the brainstem’s inhibitory signals cannot get through.
“Once you cut the spinal cord, the nerves below the injury will do whatever they want,” says , a spinal cord researcher at the University of British Columbia in Vancouver, Canada.
Freed from inhibition, the sympathetic nervous system, which is responsible for ramping up the response to stress, keeps goading the body into a more and more excited state. Medics have a name for this condition: autonomic dysreflexia. Without prompt treatment, AD can trigger a stroke or heart attack. In extreme cases, AD has proved fatal (Paraplegia, ).
Kirkland’s one unintentional experience of AD came after his catheter was blocked following surgery. “I immediately started sweating, my head pounding,” he says. “I felt like my eyes were going to pop out of my head.”
“I started sweating, my head pounding. I felt like my eyes were going to pop out of my head.”
That the response he felt was so rapid is another consequence of his spinal cord injury. Although many neurons below the injury site wither and die because they no longer receive stimulation from the brain, those that make up pain-detecting circuits prosper, biologically speaking, because their activity is normally kept in check by the brain.
Even the body’s attempts to repair the spinal injury can contribute to AD. When nerves are damaged, they release nerve growth factor – a chemical crucial for nerve repair and survival. However, NGF causes new nerves to sprout, and when it is released in large amounts in the spinal cord, there is a dramatic growth in a section of nerves responsible for relaying sensory signals such as touch. These new nerve fibres amplify the body’s cardiovascular response to a broken toe or similar stimulus.
According to Krassioukov, all of these positive feedback loops mean that the only way to treat AD and avoid its potentially lethal consequences is to quickly address whatever stimulus caused the blood pressure to spike.
For obvious reasons, then, the IPC has banned boosting on health grounds. The London Paralympics, which began this week, will feature what the IPC’s medical and science director Peter Van de Vliet calls “a combination of random and targeted blood-pressure tests” before events.
But Krassioukov, who is studying Paralympians in London during the games, feels that a more drastic change is needed. Both he and Kirkland say that, as things stand, wheelchair sports pit athletes with spinal cord injuries and damaged cardiovascular function against athletes with amputations but fully functioning cardiovascular systems. Changing Paralympic impairment classifications to avoid such a mismatch may not end the practice of boosting altogether, but it might reduce its prevalence if those with spinal cord injuries feel that they are competing on a level playing field.
As part of this re-categorisation effort, Krassioukov proposes “cardiovascular health passports”, which would be carried by all athletes with spinal injuries.
“These passports would contain a detailed profile of baseline blood pressure, heart rate and other cardiovascular measurements,” he says. Obvious differences between that profile and a profile taken after competition might help identify boosting.
Applying such schemes would be complicated, though. Classification is already a knotty, time-consuming feature of sports like wheelchair rugby, where each player receives a number based on an in-depth physical evaluation.
The IPC has shied away from considering cardiovascular features in its classification. There is just too much variation from case to case, says Van de Vliet. “Classification is an incredibly difficult puzzle. It simply isn’t practical,” he says.
Until that changes, some athletes will continue to use boosting to raise their prospects of winning – much to Kirkland’s bemusement. As he puts it: “You’re risking your life to win a damn race.”
