New York: American bobsledder Todd Hays, a 2002 Olympic silver medalist who had been seeking a bid to his fourth Olympics, has been forced to retire, the US Bobsled Federation announced.

Hays was diagnosed with an intraparenchymal hematoma following a CT scan after a training crash last Wednesday in Winterberg, Germany. An MRI confirmed that Hays risks brain damage if he continues bobsledding.

'In discussion with various experts in the field of sports-induced injuries, it was the consensus that Todd should not engage in any further bobsledding to avoid any additional trauma to a healing brain which may cause irreversible damage,' team doctor Eugene Byrne said.

Hays, 40, had been a college linebacker in American football and a US champion kickboxer. He ended a two-year sledding hiatus last year and was second in this season's World Cup two-man stop at Utah.

'This is one of the most difficult things I?ve experienced,' Hays said. 'My family and my future are more important than anything, and I need to keep that in mind as I consider what?s happened.

'This isn?t how I wanted to end my career and I?m devastated because I feel like I?m letting my team down. There are three guys in my sled that were counting on me to give them an Olympic ticket. Now I can?t do that.'

Darrin Steele, US Bobsled's chief executive, said Hays was a clear contender for a Vancouver podium finish.

'I know the decision to retire was difficult for him but I believe he made the right decision by putting his current and future health first,' Steele said. 'Todd is a champion with or without a gold medal.'