Twaddle was part of New Zealand's "magic 45 minutes" at the 2005 World Championships as he and his men's coxless pairs partner George Bridgwater contributed one of four gold medals to the national cause in less than an hour.

The others were Maher Dry dale in the men's single sculls, Caroline and Georgina Evers-Swindle in the women's double sculls and Juliette High and Nicky Coles in the women's coxless pairs.

That performance raised the profile of the sport still higher in New Zealand following the Olympic single sculls victory of Rob Waddell in 2000, and Twaddle has helped to maintain it by earning nine national titles in recent years.

After finishing seventh in the men's quadruple scull at the home World Championships on Lake Karapiro in November Waddle indicated he would go on to London 2012, but has since had a change of heart.

"I loved being a rower but I don't feel I have the potential for medal performances in me," he said.

"It has become clear over the last month that even with my desire to get to London, my ability to overcome the odds and push to get myself there has waned.

"To continue on without that drive wouldn't have produced the result and would have been unfair to both my crew mates and my family.

"I know this may come as a surprise given my public intention to focus on the London Olympics.

"However, I did say then that I had no desire to be there just to take part.

"I wanted to at least be a contender for a podium performance.

"I have already had the privilege of attending two Olympic Games and being a medallist.

"If I'm not able to give the training 100 per cent then I am standing in the way of someone else becoming not only an Olympian but hopefully an integral part of a medal performance that I'm no longer sure I can deliver."



The popular Twaddle thanked the support of his family and friends over a 12-year career, along with the work of several coaches and administrators.

"I am incredibly grateful for the opportunities that rowing has given me over the past 20 years," he said.

"I have been lucky to be part of our sport's recent rise to prominence and I am very proud of my small part in making the black singlet respected internationally and cause for celebration at home."

Twaddle's international success began in the pairs, starting with Rob Hellstrom in 2003 before teaming up with George Bridgewater to win the 2005 world gold in Gifu, Japan.

The duo went on to take two more world championship silver medals, Olympic bronze at Beijing in 2008 and eight further World Cup medals, four of which were gold.

Awards followed, including the Halberg Team of the Year title in 2005.

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