Usain Bolt is taking the remainder of this year off to rest because of tightness in his lower back.
Ricky Simms, the Olympic champion's manager, said the world-record holder in the 100m and 200m has been examined by Dr Hans Muller-Wohlfahrt in Germany and the back problem "restricts his ability to generate power in his stride".
Simms said racing "in this condition could risk injury" to the legs and added that an MRI scan showed that Bolt's achilles tendon injury has healed.
Bolt will have treatment to loosen his back and then rest, meaning he will miss the IAAF Diamond League track meets in Zurich and Brussels.
The announcement comes less than a week after Bolt lost to Tyson Gay in the 100m in Stockholm.
The 23-year-old regrets having to end his season early – but he has to prioritise the 2011 World Championships and the 2012 Olympics. "I am very disappointed to miss two of the top meetings on the circuit - Zurich and Brussels – but trust that it is better for me not to take any risks this year," he said.
"2011 and 2012 are very important championship years and I hope to be back fully fit and healthy. I would like to thank everyone for their support and look forward to coming back stronger next year."