Usain Bolt unsure over London 2017 participation

Usain Bolt has revealed that he is unsure if he will compete at the World Athletics Championships in London 2017, admitting that his appetite is wavering.

The Jamaican sprinter picked up his 10th world title on Thursday by beating Justin Gatlin in the 200m, having also beaten the American in the 100m earlier this week.

Four-time Olympic champion Michael Johnson since claimed that Bolt no longer had any rivals in the sport, and the 29-year-old does not yet know if he will look to retain his crowns in London.

"I want to run but I think the sport is not as fun as it used to be - it's more taxing," he told BBC Sport. "I can't enjoy it as much as I want to because I have to sacrifice more. It is 50-50."

Bolt, who holds the world record over 100m and 200m, also has six Olympic gold medals under his belt, and later confirmed that he would compete in Rio next summer.