The Paralympic Games are known as a joyful Games, a friendly Games, as an event far more laidback than their more famous cousin, the Olympics.

But if you think this means that every competitor at the Paralympics wears a halo, you'd be wrong.

In a perverse way, the fact that some people are willing to cheat to earn a medal at the Games can be seen as a sign of quite how seriously the competition is taken.

So how do people try and break the rules at the Paralympics, and how do their methods differ from their able-bodied counterparts?

Performance-enhancing drugs are also a problem in Paralympic sport.

The main offenders are competitors in powerlifting, just as weighlifters at the Olympics often seem to get into trouble.

In Sydney 2000, there were a total of 14 athletes who returned positive drug tests. The majority of these (10 out of 14) were powerlifting, with athletes mainly using drugs to increase power and strength.

In this regard the cheaters are little different to athletes like Ben Johnson in Olympic sprinting, or cyclist Floyd Landis in the Tour de France, who use steroids or EPO to increase muscle strength, speed, power and endurance.

There is another category of Paralympic cheats, however, whose illegal behaviour would make most people turn pale.

They are the "boosters'', mainly athletes who have spinal cord injuries such as paraplegia.

To gain an unfair advantage in their chosen sports, they try to raise their blood pressure, to trigger the kind of fight or flight response that normally happens when someone is in danger.

To do this they don't take drugs - instead, they injure themselves to trick their bodies into boosting performance.

Some of the ways that Paralympic athletes "boost'' include sitting on pins, thumb tacks or ball bearings, turning off their catheters - allowing fluid to build up inside the body - while some male athletes who go so far as to tie wire around their genital area.

Such extraordinary and totally illegal manoeuvres cause no pain to the athletes - who have no feeling in those parts of the body - but they can lead to a boost to athletic performance of up to 15 per cent.

Paralympic athletes are tested to ensure that their level of disability - or put another way, their range of movement - tallies with their registration. This is designed to stop people faking or overstating their disability to gain an advantage.

The biggest scandal in Paralympics history, however, relates to the faking of a mental rather than physical disability. In the Sydney Games of 2000, the Spanish team won the basketball event for intellectually disabled competitors.

It was only afterwards, when 10 out of the 12-member squad were found not to have any intellectual disabilities that the team was disqualified, causing a furore in Paralympic sport.

A Spanish journalist, who went undercover and became part of the Spanish squad, broke the story, claiming that officials had intentionally sought out people who were not intellectually disabled to boost the team's chances of winning.

The International Paralympic Committee reacted to the scandal by taking all intellectual disability events off the program for Athens in 2004.

There was more disappointment in store for genuinely intellectually disabled athletes, when the IPC left their events out of the Beijing Games as well.

There is some hope for the future, however, as the IPC will revisit its decision after Beijing, so there could be some intellectual disability events on the program for London in four years time.