IN most sports, people have to work from the ground up, and One motor-racing champions Alain Prost and Ayrton Senna were no exception. Like many of their colleagues, they began their careers a few centimetres from the ground in a go-kart. A sport that does not require a standard driving licence, go-karting is enjoyed by young and old. Enthusiast Darren Shaw said: ''All the top guys in Formula One, such as Prost and Senna, drove go-karts before they started their careers. ''If you want to be a professional racing driver, go-karting is a good way to develop your skills.'' Go-karting is a sport also enjoyed by the rich and famous. Even Britain's royal family participate. Prince William and Prince Harry spent some of their summer holidays on a circuit under the watchful eye of the Princess of Wales. Go-karts have a very low centre of gravity and have the weight distributed evenly across the wide frame of the kart - the engine is behind the driver, while the petrol tank is positioned between the legs - so high speeds can be clocked without fear of thekart tipping over. Although it is a safe sport, it does require strong arms to keep the kart on track. One enthusiast said many drivers experienced tunnel vision; they could only see directly in front of them because their side vision was blurred due to the high speeds involved. Unlike racing cars, there is no suspension nor gears in go-karts. ''The only method to reduce the bouncing is adjusting the pressure of the tires,'' Darren said. ''But, only advanced drivers know how to achieve optimum performance using this method.'' Go-karting has become a popular sport in Hong Kong over the past few years, particularly since the introduction of the International Kart Grand Prix. Staged in November at Victoria Park, it attracts top drivers from Europe, Japan and Australia. ''As the top race of its kind in the world, it can upgrade you to a professional car racing driver in formula three,'' Darren said. There is only one karting track in Hong Kong at Mai Po. The area, designated for redevelopment, is leased by the Hong Kong Kart Club, which has about 150 members participating in competitions at the weekend. The club does not rent equipment, but administrator Julia Ho can put you in touch with someone who can, although she says it can often prove costly after you have also paid for use of the track. Julia said the club had applied to have a new track supplied and financed by the Government so the sport would be affordable for young people, but no decision had been made.