12 September 2008

Could Bolt have run 9.55s?

Swedish scientists claim Usain Bolt could have run 9.55s if he hadn't started celebrating before the end of the race. Is this possible? Not a chance, says Health24's FitnessDoc.

Yesterday, the news wires were buzzing with the news that scientists in Oslo predicted that Usain Bolt, Jamaica's triple Olympic champion, would have run 9.55 seconds had he not celebrated prematurely in his 100m final in Beijing. However, Health24's FitnessDoc doesn't agree. Here's his take on the study:

It was on the radios, internet, TV news, all over. A while back, just after that race, we speculated that a 9.61s time was about the limit, given the split times that were available.

So this 9.55s is quite different from that. And far be it from me to criticise the physicist's assumptions, and calculations, but what we have here is a classic case of losing sight of the wood for the trees. Their method involved looking at the final two seconds of the race, where Bolt began his celebrations, and compared his acceleration to that of Richard Thompson, who finished second.

They looked at two possible outcomes: one is that he maintained the same acceleration as Thompson (that is, slowed down, because all athletes slow down at the end of a 100m race); and the second is if he maintained an acceleration 0.5m/s2 greater than Thompson.

It was in the second of these scenarios that they worked out that he'd run 9.55s. But the problem with this emerges when you consider the official 10m splits from the race, courtesy the IAAF analysis and a website in which they discuss the race.

So let's look at the analysis, and let me start by asking a simple question: Where in this race are you going to find 0.14 seconds to help Bolt run 9.55 seconds? The answer, as you'll see, is that you won't find it at the end of the race, in the celebrations. It's just not physiologically possible...

The splits
These are the split times from Bolt's race, according to the IAAF analysis. The second illustration shows the times making some basic assumptions (apologies for the lack of integration and physics equations, but I wish to make a point using simplicity as the vehicle).

Again, ask the question: Where are you going to help Bolt knock 0.14 seconds off his time?

The red line represents the actual performance. It adds up to a time of 9.685 seconds, considering also that Bolt's reaction time was 0.165 seconds.

You'll note that Bolt's fastest 10m interval was from 60 to 70m, taking 0.82 seconds. I must point out that no one has ever measured a human being running a 10m interval faster than this.

In our analysis of the race, we got a lot of interesting discussion and data from people, and of all the recorded 10m split times, this is the fastest ever measured. To speed up for the remaining 30m would represent not only the fastest splits ever run, but also the longest period for which they are ever run. That is unlikely.

The blue line, to simplify, represents Bolt's projected splits if he continues to accelerate. This is effectively the assumption made by the physicists when they calculate his 9.55 second time. If you want to find 0.14 seconds at the end of the race (and answer my simple question), then you have to project that Bolt continues to speed up.

According to this assumption, Bolt would run faster and faster - he has to, in order to do what was projected by the analysis. Therefore, he'd break 0.8s for the 10m intervals.

Again though, I must stress that this has never been done - I believe it to be impossible, and the whole basis for the argument by the physicists is flawed because there is no reason to believe that Bolt would continue to run faster than Thompson, or accelerate.

The green line represents what I would in fact consider a more likely scenario. In this case, Bolt maintains that top speed that he hits between 60 and 70m. He thus runs the final 30m at 0.82 seconds/10m speed. If he does this, then he runs 9.605 seconds.

In reality, I suspect that Bolt would slow down at the end anyway, even without his celebrations. His most likely performance is thus somewhere between 9.61 seconds and 9.69 seconds.

Now, I know there's no fancy physics here, no integration. Just split times, and a very simple question: Where in this race are you going to find 0.14 seconds to help Bolt run 9.55 seconds?

Answer, you can't find that time at the end of the race. Unless you assume that Bolt is going to run a 0.79 second 10m interval somewhere in the race. But that, I'm afraid, is not possible, and therefore, you cannot conclude that he would have run 9.55 seconds.

What is possible?
Having said this, I make the suggestion that Bolt's celebrations cost him only about 0.05 seconds. However, that's not to say he cannot still run under 9.60 seconds.

One area for improvement is the start - a reaction time of 0.165 seconds can easily be cut down. Asafa Powell, for example, had a reaction time of 0.134 seconds in Beijing. Therefore, we can estimate that Bolt might get a 0.140 second reaction time.

If that happens, then suddenly he's down to 9.66 seconds. Add to this the fact that there was no tail-wind in Beijing, and it has been estimated that a tailwind of 1m/s improves 100m times by 0.05 seconds.

Therefore, on an ideal day, with a tailwind of 1m/s (it could be as much as 2m/s, recall), a super fast reaction time, Bolt could run 9.61 seconds, and still celebrate. Take away those celebrations (another 0.05 seconds, in my estimation), and we have a 9.56 seconds.

But there is no way the 9.55 second time would have come without those celebrations - the trees just got in the way.

(Health24's FitnessDoc, Dr Ross Tucker, August 2008. Dr Tucker also blogs on

Read more:
The most devastating 9.69 seconds in sporting history
Bolt: the world's fastest man


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