No sweat for Bolt to break record, says mathematician

Without any extra effort or fitness, Usain Bolt could slice a relatively massive 0.13 seconds from his historic 9.58 second 100-metre world record sprint at the 2009 World Championships in Berlin.

The reduction is 0.03 seconds faster than a previous estimate of Bolt's minimum possible time, pegged at 9.48 seconds by Mark Denny of Stanford University in California.

The factors that would effortlessly lower his time to 9.45 seconds are proposed by mathematician John Barrow at the University of Cambridge.

Firstly, Barrow notes that Bolt is notoriously slow off the blocks. In Berlin, he was second slowest to react to the starting gun, taking 0.146 seconds to get going compared with 0.119 seconds for the speediest starter. This means that it actually took Bolt just 9.434 seconds to run the 100 metres.

Under international athletics rules, sprinters are judged to have made a false start if they leave the blocks within 0.1 seconds of the starting gun. But even with this limitation, Bolt could safely cut his reaction time from 0.146 to 0.13 seconds. This would lower the final time for the sprint from 9.58 to 9.56 seconds.

Secondly, when Bolt ran his epic race, he had a tailwind of just 0.9 metres per second. Barrow calculates that if he had the maximum allowable tailwind of 2 metres per second, he would waste less effort battling wind drag. And if under those conditions he managed to achieve a perfect reaction time of 0.1 seconds, he would reduce his record to 9.48 seconds.

Already a full tenth of a second faster than his Berlin record, Bolt could finally shave a further 0.03 seconds off his time if he ran the race at an altitude up to, but not exceeding, 1000 metres, where the air is thinner and offers less resistance. Records don't stand unless they're at altitudes below 1000 metres.

"These are amazing improvements but they can all happen without Bolt becoming a better sprinter," Barrow writes. "They serve to illustrate how far we are from any type of 'ultimate' sprinting speed in the men's 100 metres, and the scale of the improvements possible."

Denny agrees that there are many reasons why it should be possible for Bolt to run faster, but that these seldom materialise in reality. "It's easy to say Bolt could gain 0.05 seconds with a perfect start, but trying to achieve that sort of quick getaway got him disqualified in the finals of last year's world championships," he says.

Also, if the tailwind is slightly more than 2 metres per second, the record wouldn't count, and with London at sea level, there will be no extra altitude to aid him during this summer's Olympics, says Denny, who worked out his "theoretical maximum" on the basis of historical sprint times.

Controversially, Barrow also argues that Bolt is no longer the fastest man on earth. At the end of last season, Bolt's training partner, Yohan Blake, ran the second-fastest 200 metres ever in Daegu, South Korea, at 19.26 seconds, a shade short of Bolt's world record breaking 19.19 second sprint in Berlin in 2009.

But Blake took an eternity to get going ? no less than 0.27 seconds. This meant that it took Blake just 18.99 seconds to run the 200 metres itself, compared with 19.06 seconds for Bolt in Berlin after factoring in his starting time. Halving these times to get a theoretical 100-metre score means that Blake covered the distance in 9.495 seconds compared to Bolt's 9.53 seconds, making Blake faster than Bolt ? in theory at least.

Journal reference: Significance, DOI: 10.1111/j.1740-9713.2012.00552.x

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