When elite sportsmen and women discuss the pain and dedication needed to win an Olympic medal, they talk about the great sacrifices made en route to the podium.
The general image created is one of sustained intense exercise reinforced by rigorous nutrition and an almost monastic seclusion from the social temptations enjoyed by their peers.
Some athletes arriving in London ahead of the start of the Paralympic Games next Wednesday will line up for their competitions aware that their pursuit of gold and glory could see them make the ultimate sacrifice.
Experts and fellow competitors past and present allege that a significant number of wheelchair athletes engage in a form of cheating which make the sort of incredible differences in performance needed for victory. Yet, it can also kill.
It does not involve injecting or ingesting banned drugs in the manner which has repeatedly made fools and liars of many able-bodied and Paralympic athletes since the fight against doping in sport began in the late 1960s.
The method of choice for Paralympic athletes is known as 'boosting' and involves tricking the body into increasing blood pressure in order to produce a rush of energy and adrenalin.
The tools of this particular trade are not so subtle or sleek as a needle. Instead, they include a hammer for breaking bones or pegs and clips with which to block catheter tubes. Some male athletes will tightly bind their scrotum with wire, pierce them with carpet tacks or twist and sit on them. All in the name of sporting ambition.
The intention is to induce a natural reaction, known as autonomic dysreflexia or AD, for short. When quadriplegic individuals experience irritation below the damaged portion of their spinal cord, their bodies sense the discomfort and respond by narrowing blood cells, causing blood pressure to spike. Their brains, however, are unable to feel the pain.
It can occur naturally and spontaneously in people suffering from particular types of spinal cord injury (SCI) and is actually classed as a medical emergency.
Wheelchair athletes have long recognised the competitive advantage which it might represent and have set about trying to deliberately bring about the effect by 'boosting'.
I first became aware of it while researching an article for Esquire magazine in the mid-1990s. I was in the car park of an athletics track in the south of England and watched open-mouthed as one international-standard wheelchair competitor took a hammer to his big toe to demonstrate how 'boosting' was done before I saw for myself the startling effects on his performance.
Estimates as to just how effective it is are subjective and unreliable. The results are as individual to competitors as the nature of their injuries. However, one leading authority told me that 'boosting' might improve times by 10 per cent. If replicated in, say, a marathon, such progress would knock 12 minutes off an athlete's personal best.
The problem is that, once produced, AD cannot be controlled. There are lots of locker room stories among the Paralympic fraternity about those who have suffered side-effects but, as yet, there are no documented cases in a sporting context.
Clinically, the toll is staggering. A study by one of the world's experts of the reported medical instances numbers seven deaths, 14 strokes and five heart attacks. That, he stressed, was likely to be merely "the tip of the iceberg".
Athletes freely acknowledge the dangers. One, set to play a prominent role in next Wednesday's Opening Ceremony said he knew some who 'boosted' but hadn't done so himself because it was tantamount to risking suicide. Another, who did 'boost', described it as "like throwing gasoline onto a fire".
A number to whom I have spoken believe it's not cheating but provides the chance to level the playing field with competitors in a way which their bodies deny them.
Not all wheelchair athletes have the same injuries or respond to injuries in the same way. Many experience low blood pressure and, with it, tiredness, weak muscles and poor brain function, all of which make them less able rivals for those who do not have similar symptoms.
Nevertheless, 'boosting' is outlawed by the International Paralympic Committee. They will be screening athletes for signs of having used the practice before races in London, just as they did in Beijing four years ago.
Officials check athletes' blood pressures before the start of events and, if they're high and don't subside, can prevent individuals from starting.
Privately, the IPC concedes that it is almost impossible to positively determine whether someone has 'boosted' or is suffering instead from a legitimate medical condition or even just pre-race nerves.
They are also wary of the potential for legal action by athletes suspended following a pre-race test. The prizes on offer are not just gold medals but the six-figure annual earnings of elite wheelchair competitors on the international road racing circuit.
Such concerns may not be uppermost in the minds of spectators gathering in the main Paralympic Stadium over the next three weeks. However, some leading officials are anxious. As one remarked to me: "All it takes is one person to not completely know what they're doing and we're going to have a death on our hands."