Usain Bolt, whose 9.58 seconds world record for the 100 metres is now 16 years old, says he could have run 9.42 in the carbon-plated "super-spikes" that today's sprinters are racing in.

The Jamaican set his mark at the 2009 world championships in Berlin, breaking his own 9.69 record from the previous year's Beijing Olympics, and it has now stood for longer than the 14 years of Jim Hines's 9.95 set at the 1968 Mexico City Olympics.

Research by Puma, the company that sponsored him through his glorious era of dominance, predicted that Bolt would run 9.42 in today's shoes and, speaking at an event ahead of the world championships in Tokyo, he said: "I fully agree.

"Someone who continued after I retired was Shelly-Anne Fraser-Pryce and I saw what she did - she got faster with the spikes.

"I

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