American sprinter Tyson Gay has a mild strain in a muscle in the back of his left leg. He has been told to limit his activity to light exertion over the next two weeks.

The 25-year-old runner pulled up during the men's 200-metre qualifying heat on Saturday at the U.S. Track and Field Trials in Eugene, Oregon.

Gay, running in the seventh lane, had run 14 strides and was speeding to the lead in the first turn. Suddenly, he flew through the air and fell. He lay on the ground in visible pain while grabbing his left leg and had to be taken off the track on a stretcher.

An MRI that afternoon revealed the strain, and he was diagnosed with a severe cramp in his hamstring.

Representatives of Gay released a statement Sunday that said he is "expected to engage in 'active rest' for up to 12-14 days, with light physical activity increasing through that period, then resume training."

Gay is the defending world champion in the 200 metres, but would have had to finish in the top three at the U.S. trials to gain a berth in Beijing.

Gay had already qualified for the U.S. Olympic team when he won the men's 100 metres on Sunday in a wind-assisted 9.68 seconds. He has been considered a favourite to win Olympic gold in the 100 metres along with Asafa Powell and Usain Bolt, both of Jamaica.

The 100 is scheduled for August 15. If Gay is healthy, he was also expected to be named a member of the men's 4x100 relay team. He is scheduled to run the 100 at the London Grand Prix on July 24-25.

With files from the Associated Press

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