Wednesday, July 22, 2009

How Fast can Usain Bolt Run?

The IAAF World Championships begins in less than a month and all eyes will be on the 100m and 200m world record holder, Usain Bolt from Jamaica. We all remember the Beijing Olympics in 2008, when Bolt ran the 100m in 9.69 seconds, throwing out his arms and pumping his chest before crossing the line. There has been a lot of speculation about how fast he could have run with some suggesting a time of 9.55 seconds .

The publishers of the study above, made use of video analysis to estimate this potential world record time. In fact they used video from Beijing Olympics broadcast productions from NBC, BBC and NRK (a Norwegian Channel). If you are a regular reader of our posts you will already know about many of the techniques they used to analyze the video. Lets look at how they did it.

When you or I setup to capture video of a sporting performance, we know how important the position of the camera is. In this case however the researchers did not have access to the stadium and athletes in Beijing and therefore had to make use of broadcast footage. In most cases this footage includes moving cameras and camera angles that are not always conducive to accurate measurement.

The publishers of the article used basic physics to estimate the possible finish time for Usain Bolt had he not celebrated 20 meters before crossing the line. The basic equations are well known:
Velocity (speed) = Distance/Time
Acceleration = Velocity/Time

So if we can find the distance Bolt covered and the time he took to cover that distance we would have his velocity or speed. We could measure that speed, from the video footage, over numerous intervals to determine how it is changing. Likewise, if we know his velocity (speed) we can measure his acceleration and how it changes over the same intervals.
The publishers of the study estimated Bolts speed and acceleration at the interval before he started to celebrate. At this point his speed and acceleration slow. To determine the predicted finishing time, the researchers assumed that Bolts acceleration could be maintained over the last 20 meters of the race, had he not celebrated. In this way they were able to predict a finishing time of 9.55 seconds.

You probably want to know how they were able to determine distance covered and the time it took. This information was all obtained from the broadcast video. The video used was from NBC and can be found at . Below is similar video of the race :

In the video you will see the camera rail running from the left to the right at the bottom of the image. This camera rail has bolts spaced evenly along it. By knowing the distance between the bolts on the track and that the start line is at 0 meters and the finish line at 100 meters, we can determine Usain Bolts position relative to the rail bolts at numerous intervals.

You will also see the stadium time clock and the broadcast time clock in the video. These clocks can be used to determine the time at which Bolt reached each interval.
We now have all the information we need. Distance covered and the time it took. From this we can determine his speed and acceleration at all intervals and predict his finishing time had he not begun his celebrations early.

We would like to thank the study authors H. K. Eriksen, J. R. Kristiansen, Ø. Langangen and I. K. Wehus for doing this fun study and we look forward to seeing whether Usain Bolt can get anywhere close to this predicted World record at the IAAF World Championships in Berlin in August.

Please let us know if you want more details on this study or just want to leave a comment. We love to hear from you.


Sean Weatherby said...

there's little doubt now (as if there was any before) that Usain Bolt is the fastest man in the world

Dudley Tabakin said...

No doubt at all. Now the question is how much faster can he go?

Anonymous said...

Usain is one of the few unbeatable athletes that i would hate to see lose a race. i just hope the pressure doesn't get to him.

Anonymous said...

so how fast can he run?

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