## 07 March, 2016

A few days ago I run across an article with title "Justin Gatlin breaks Usain Bolt's 100 m record with 9.45 second dash on Japanese television show". In fact the internet was brimming with articles on the same subject. All written more or less in the same ludicrous admiring tone talking about Gatlin's feat. And of course, downplaying the fact that Gatlin was propelled along the track by fans creating a favourable wind of 20 m/s (incorrectly reported in most publications as 20 miles per hour i.e. roughly 9 m/s).

If this is where Athletics are heading I will stop interesting myself in this sport and close this blog. (Perhaps I could take up something else, writing a blog on pinballs for instance. Now, that sounds like a good idea).

This farcical performance was staged for the japanese television show Kasupei. The expression of the japanese journalists is priceless.

But what is the real value of Gatlin's performance? First let us analyse the wind assistance. Looking at the fan set-up it is highly improbable that a 20 m/s wind could be indeed blowing  all along the track. I am ready to settle for a more conservative 10 m/s. In a paper published 15 years ago, Mureika estimates the time gain due to an assisting wind. The formula he proposes breaks down when the speed of the wind is higher than that of the athlete but if one limits oneself to the case where the two speeds are equal one finds that the time gain for a 10 s 100 m race is of the order of 0.3-0.6 seconds. Jean-Pierre Vazel has published a most interesting article on the effects of wind and has proposed an empirical table relating wind speed to performance gain over 100 m. Vazel's analysis covers only the range of "realistic" speeds 0-5 m/s but one can attempt an (admittedly hazardous) extrapolation to wind speeds of 10 to 20 m/s obtaining a time gain of 0.25-0.35 s. So let us take the most conservative estimate and decide that Gatlin's performance must be corrected by 0.25 s, which results to a mere 9.70 s. We are far from Bolt's world record of 9.58 s even if we correct it to 9.63 s due to wind assistance (+0.9 m/s).

But, wait, things are getting worse. Vazel has analysed the video of Gatlin's attempt and points out that a) Gatlin has anticipated the start and b) the timing was not triggered by the starter's gun but most probably started at the athlete's first move. He estimates the gain due to these irregularities to roughly 0.10-0.15 s. (The analysis of J.-P. Vazel is much more detailed than this and, if you can understand french, I urge to read his post). Putting the two corrections together we arrive at a correction between 0.35-0.50 s. So, at the very best Gatlin has run a 9.80 s 100 m but most probably closer to 9.95 s.  In fact Vazel reports that in Japan, during the same show, Gatlin has run a 9.64 s 100 m with rolling start and has estimated his corrected time to 9.95 s compatible with the wind-assisted performance. On the other hand Gatlin's best time of 2015, 9.74 s, was registered in May, his World Championships performance being 9.80 s. So a 9.95 s in November is quite a respectable performance but nothing to write home about.

So, No! Gatlin did not break  Bolt's 100 m record. He did not even come close. Despite this Gatlin keeps boasting that he will finally beat Bolt at the 2016, Rio, Olympics. "I'm going to win. We are bringing  the gold medal back to the USA. We are going on a tour around the country with it around my neck like a gold chain", Gatlin said recently at an interview. Bolt's riposte was a stinging one: "Keep talking and I will keep working hard". Well, Rio is only a few months away.

This wind-assisted attempt made me go back to the archives and look-up the fastest times registered under excessive wind speeds. I was aware of W. Snoddy's, 1978, 9.87 s performance obtained with a 11.2 m/s wind. A correction for the wind transforms it into a quite respectable 10.15 s, not in disagreement with Snoddy's best performance over 200 m  of 20.27 s (he was a 200 m rather than 100 m specialist). Other people estimate his corrected time to something at least 0.10 s higher. Anyhow, the wind reading was a rough estimate: it was most probably announced at 25 miles per hour which is equal to 11.2 m/s. Wind gauges, in particular at that time, were not calibrated for such squall-like winds. (Just as an anecdotal information, W. Snoddy ran a 19.6 s 200 m in 1983 but this performance is listed as a "doubtful distance" one. He ran a legal 20.64 s that same year).

The absolute record in wind-assisted races, as far as wind speed is concerned, is held by C. Garpenborg from Sweden. He ran a manual 9.9 s in 1976, in Las Vegas, assisted by a 16.6 m/s wind (this speed is tantalisingly close to 60 km/h, so one could again surmise that the wind speed is just an estimate). Wikipedia reports his time as 9.84 s but I have trouble believing that his electronic time could have been better than the manual one.

Garpenborg, whose legal record over 100 m is a respectable 10.25 m, occupies a unique position in the Athletics elite. He is the only european to win the US championships over 100 m. His time of 10.39 s was sufficient for the victory, most probably because the best american sprinters were concentrating on the qualification for the Olympics Games, the famous "Olympic Trials". On European ground his best performance is a second place in the 1977 Indoor Championships where he was beaten by Borzov by a mere 0.01 s over 60 m. (Many spectators saw Garpenborg beating Borzov. Unfortunately no video of the event is available).