From ABC News:
Like blood doping, boosting increases the amount of oxygenated blood circulating in the body. But instead of using blood transfusions and erythropoietin injections, boosters break their toes, block their catheters and crush their scrotums...That's a bit oversimplified; boosting blood pressure wouldn't per se increase oxygen delivery unless cardiac output was also enhanced (perhaps it is, via increased rate).
Boosting uses self-inflicted injuries to trigger autonomic dysreflexia, a condition that's considered a medical emergency when it happens by accident. Although boosters can't feel the pain, it activates the sympathetic nervous system, causing risky rises in blood pressure.
"If you raise your blood pressure, your heart theoretically pumps more blood. If your heart pumps more blood, you get more oxygen. And if you get more oxygen, your performance is improved," said Bhambhani, author of a 1994 study that found boosting could improve wheelchair race times by nearly 10 percent.
From The Independent:
Brad Zdanivsky, a 36-year-old Canadian quadriplegic climber, told the BBC World Service that he had experimented by at first ignoring the will to urinate and, later, by "using an electrical stimulus on my leg, my toe and even my testicles".And finally, from the BBC:
Tanni Grey-Thompson, the veteran British wheelchair racer, says she had heard of an athlete who tapped nails into his feet. One other reported method involves breaking toes with hammers...
Boosting is banned by the International Paralympic Committee (IPC), but it can be hard to detect and there are no reliable statistics on the number of athletes who do it. Around 17 per cent of 60 Paralympians surveyed in Beijing in 2008 admitted to boosting, but Dr Andrei Krassioukov, an associate professor at the University of British Columbia in Canada and a spinal injuries expert, said the figure could be closer to 30 per cent...
The IPC says it will continue to monitor athletes closely before events at the London Games... If athletes are found to have a systolic blood pressure of 180mm of mercury or above, they will not be allowed to compete in "the particular competition in question". But they will not receive a long-term ban...
Brad Zdanivsky argues that checks like this will not be effective in cutting out boosting. He says you would need to test an athlete's blood pressure regularly over a sustained period to be able to know for sure whether any given reading was natural or "boosted".
"There is no real solution, it is an ugly can of worms that no-one wants to open it and talk about," says Zdanivsky.More at all three links for those interested.