BIRMINGHAM, United Kingdom - Usain Bolt has been declared fully fit to defend his three Olympic titles, with the Jamaican team doctor insisting that the sprint king's performance is "on track".

Bolt has struggled with leg and back problems in recent weeks while world champion compatriot Yohan Blake beat him in the 100m and 200m at the Jamaican Olympic trials.

But team doctor Winston Dawes said he expects Bolt to be in prime shape by the time the track and field events start on August 3.

"He's back fully. He has been training very, very hard and his performance is on track," Dawes told the BBC.

"We expect he'll be fully fit by the time the Olympics come around. He had some slight cramps in his legs. He had had an accident before, so that might have shaken him up a little." (AFP)