"I didn't expect this to be so difficult; it is tough," the 38-year-old former world-record holder told idnes.cz, saying a heel injury that forced him to pull out of the London Olympics last year was the final straw.
"The heel is probably the biggest problem I have ever had," added Sebrle, who had intended to make the Moscow world championships in August his final event.
The Czech army officer won gold at the 2004 Olympics in Athens and held the world decathlon record for 11 years until Ashton Eaton of the United States beat it last year.
Sebrle also won the world championship title in Osaka in 2007 and has two European championship golds.
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