There is a deadly serious message behind the fun and celebrations of the British Transplant Games - and that is to save lives.

Every competitor heading for Medway next August is alive thanks to someone who put their name on the donor register.

And now organisers want to boost the numbers on the list so that more patients can be helped.

Recipients of organs and families of donors gathered at the launch, which included moving speeches from athletes, including five-year-old George Penhaligan, who showed the medal he gained at this year's Belfast games.

Members of the Jumpers trampoline club in Gillingham took advantage of their cavernous new venue inside Britain's second oldest cathedral to leap enthusiastically into the nave.

Guests were told only one in three people in the UK is registered to donate their organs, while 96% of people would accept an organ if they needed one.

Athlete James Baxter, 38, from Walderslade, who had a heart and double lung transplant in January 2001, said: "People need to think 'would they accept a transplant or would they turn it down as readily as they refuse to give one?

"We are all standing here today because of transplants, and it's important that people join the register and support the games, which is a fantastic event."

Edwin Boorman, chairman of the local organising committee and president of the KM Group, which is supporting the event, added: "The whole point of these games is to spread the word about the donation of organs. Only one in three people in the county have said they will donate."

Richard Hicks, from Medway Council, said 2012 would be a year of celebration for Medway with events including the 200th anniversary of Charles Dickens, the anniversary of the Royal Engineers making Medway their home, the 10th year of the Universities at Medway, the Queen's Diamond Jubilee and the London Olympics.

The games at Medway Park will take place from August 23 to 26 and feature sports including track and field, tennis, table tennis, badminton and swimming.

More than 600 recipients of a life-saving organ transplant will take part and an estimated 1,500 supporters are expected to visit, bringing roughly £2.5 million into the county's economy.

People are being encouraged to sign up to the donor register and enter a donor run, covering distances from 3km to 5km.