**LRC Brain Teaser asks: How is Bolt’s 200m WR almost exactly twice his 100m WR?**

Wejo and Rojo, you might think just doubling your 100m PB is the quick answer, but there’s more behind the story.

Usain Bolt’s PB for the 100 and 200 meters is 9.58 and 19.19 respectively.

In the 200 meters, you will never run the first 100m all out hence the importance of speed reserve.

Plus, there is always a slowdown over the final 100m straightaway, hence the importance of the speed endurance training component.

My** theoretical calculations** for 100m and 200m is doubled your best 100m time +/- 0.2 seconds. This is a good indicator on what you need to improve on the respective events, or to determine which is your “better” event.

9.58 x 2 = 19.16

19.16+/-0.2 =18.96 to 19.36range.

So there is potential improvement on the current WR considering his 19.19 was not under ideal wind conditions. Plus, it was after 4 rounds of the 100m and 3 rounds of the 200m.

18.99 is just an insane WR for 200 meters.

Usain Bolt’s WR splits were 5.60, 9.92, 14.44 and 19.19. That’s 9.92 and 9.27 100m splits (compared to Beijing’s 9.98 and 9.32)

From his 100m WR, his “speed reserve” is 9.58 – 9.92 = 0.34 seconds, with the curve in consideration.

If you take away 1 full second for acceleration out of the blocks, as referenced in the Valeri Borzov – Training Procedures in Sprinting article, that gives his 200m breakdown:

(1.0 + 8.92) + 9.27 = 19.19

Therefore his “speed endurance” slowdown is 9.27 – 8.92 = 0.35 seconds.

**So doubling your best 100m time may look all neat and precise, but it’s really twice your speed reserve (0.34 for each 100m segment) plus your second half slowdown (0.35) that determines your 200m time.**

Compared to Michael Johnson’s 19.32 from the 1996 Atlanta Olympics, his splits were **10.12 + 9.20 = 19.32**, therefore Johnson still has the fastest second half ever recorded.

There are a lot of implicit assumptions that I’m not comfortable with. Let me start off by saying I agree that Bolt can run faster considering all rounds he had to run, that he had absolutely no competition during the race and that he had unfavorable wind.

The first assumption is that all of the acceleration is due from the first 30 meters. I think this is clearly false. If you look at the biomechanics project from the 100 meter final male or female you can see people continue to accelerate up to about 50-60 meters. So the 1 sec adjustment due to accleration is a gross underestimation. Additionally, when you calculated the 1 second difference that is incorrect in itself because the crouching start was not fully automatic. You cant compare a crouching 30 and a 100 meter split if they arent timed the same. Because the 100 meter split had an FAT start you should add the reaction time to the crouching start. I am assuming that the crouching times on the website you referenced were handtimed when the runner starts because not even usain bolt has run a 3.5 crouching 30 (even considering his reaction time) and his max speed is around 12.3 m/s and not 12 m/s (not to mention a 6.4 60m is ridiculously fast, where only a handful of people have ever run that fast).

Looking at the berlin data on bolt, his crouching 30 minus his reaction time was 3.63. His best flying 30 occured from 50-80 meters and was 2.45 seconds. As we can see here that his adjustment according to your assumptions should be 1.18 seconds.

This leads me to your second assumption, which is, that people can run their top speed for 100 meters. I think you are assuming this because you use 8.92 as pure sprinting time and the other second was removed because of a comparison with a fly 30 which displays top speed. Usain bolt was able to say within 97% of his top speed for 50 meters. Who knows how long he could have stayed running his top speed. But we know from the 200 meter data that his middle and fastest 100 (50-150) he averaged 11.3 m/s which is only 92% of his max speed. It really depends how you define top speed. Is it within 90% of his max? 95%? I would define it as about 97%-98% because, from the berlin data, usain and powell ran above that percent the whole time of their fastest 30. So if we assume that one can run his max speed as defined as 97%-98% of his top speed for 100 meters then bolts 8.92 should be 8.20. Thus his acceleration adjustment should be 1.72 instead of 1.

It just doesn’t seem like the calculation for speed of endurance slowdown is fair. I dont think the answer to letruns question is as simple as you make it out to be. My thoughts were always that world class sprinters should run less than twice their 100 PR based off the fact that acceleration is a large part of the first 100 and the second 100 was flying (and that they have great “speed endurance”). Maybe if you give more details of your calculations it will make more sense.