NAIROBI, Aug. 23 -- Olympic 800m champion David Rudisha has ruled himself out of the World Championships, which will be held in Doha, Qatar from September 28 to October 6.

The 30-year-old has not taken part in any competitive race since July 2017 because of a nagging injury, a quad muscle strain and back problems.

Manager Michel Boeting confirmed that the world record holder will miss the Kenyan trials on September 13, which rules him out of making the national team and a chance to reclaim his world title in Doha.

"He won't be ready for the trials," Rudisha's manager said. "Therefore he wouldn't be at the World championships."

Back in 2013, Rudisha sat out more than one year of competition due to a right knee injury after running in New York.

However, he overcame the injury and went on to win the 2017 world and 2016 Olympic titles, becoming the first repeat Olympic men's 800m champion since New Zealand's Peter Snell in 1964.

Rudisha owns the three fastest times in history, including the world record 1:40.91 set in an epic 2017 Olympic final.

Last year, manager Boeting said he does not expect Rudisha to compete until August 2018.

It is a year now and Rudisha has shown little signs of returning to action. Instead, he has been enduring several visits to the doctors in Kenya and the Netherlands, which are yet to yield any success.

Rudisha has also endured an injury to his upper hamstring muscle, a similar problem that saw him miss out to defend his crown at the 2013 World Championships in Moscow, Russia.

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