Jamaican sprint star Usain Bolt has expressed sadness that doping issues rather than track talk is dominating the build-up to the world championships.

Athletics’ world governing body IAAF has recently been mired with allegations over doping, while Bolt’s main sprint rival is Justin Gatlin, the controversial American who has served two doping bans, the latter for four years after testing positive for testosterone.

“It’s really taken centre stage,” Bolt said of the doping issue. “All I’ve been hearing over the past couple of weeks is doping, doping, doping.

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“The majority of questions are about doping, it’s definitely sad.”

But Bolt played down suggestions that he was the “saviour” of track and field, saying he alone was not capable to turning the tide.

“Initially I’m running for myself, that’s what I do,” he said. “People say I need to win for the sport, but there are a lot other athletes who are running clean.

“It’s not only on me because I can’t do it myself.

“I think it’s the responsibility of all the athletes to take it upon themselves to help save the sport and show the sport can go far, without drugs cheats or athletes who’ve taken drugs.

“I just try to do what’s right by the rules of the IAAF, WADA and everybody. We all know the rules and we just have to abide them.

“It’s not only up to me because I can’t do it by myself because I’m not the only one in the sport.

“It’s up to all the athletes to understand the rules and abide by them and just work hard to be the best: it will make sports a better place.”

Bolt might have endured a stop-start season debut, but he vowed he is ready to defend his double sprint titles at the world champs, which begin in Beijing on Saturday.

The towering Jamaican gets his campaign under way in heats for the 100m on the opening day of the competition that runs until August 30.

For Bolt, it will signify a return to Beijing’s iconic Bird’s Nest stadium, where he first made his name with a thrilling golden treble in the 2008 Beijing Games.

“I’ve been training hard these past few weeks to put myself in the best possible condition to run well and defend my titles over the next week,” Bolt insisted.

“Coach (Glen Mills) is happy and that’s always key because when he’s happy I know I’m in good nick.”

Bolt added that memories of seven years ago were not lost on him.

“Beijing was where it all started for me at the Olympic Games in 2008. I have great memories of this city and the stadium. It’s great to be back here, I’m looking forward to getting on the track on Saturday.”

-AAP