Hot on the heels of a 20.66s World Record for double-amputees in Lyon a week ago, Alan Oliveira of Brazil, the fastest double amputee in the world, today destroyed his own 100m World Record with a performance of 10.57s in the London Olympic stadium.
I wrote about his emergence as the heir to Oscar Pistorius last week, describing the implications of his incredible improvements in 2013. He last week won the 100m, 200m and 400m titles in the IPC World Championships, and is now a staggering 0.44s faster than the next fastest in history at 100m (Pistorius). The improvement has come within the last two months, because prior to that, Oliveira's best 100m time was 11.33s.
The leg length - in play, but a red herring
Of course, the current debate is all about his legs, and more specifically, their length. That is a red herring. While partly true, there are many reasons to suggest that what Oliveira has achieved in 2013 is not the result of excessively long legs, but some other factor, which has already been proven to exist by scientific research. Unfortunately, the IPC seem intent on pursuing length as the critical one, with new rules controlling length to be announced soon.
It's unclear what this will mean for Oliveira in the short term, but the problem is that they won't solve the larger problem, and the next athlete to come along with once again push the sport into the same dilemma.
Let's look at the leg length issue in a bit more detail.
London 2012 flashback
When he defeated Pistorius in the London 2012 200m final last year, the accusation made by Pistorius was that he "couldn't compete with Alan's (long) stride length". An easy explanation to test, because all it took was counting the strides, and it turned out that Oliveira's stride was not all that long. In fact, Pistorius took fewer strides than Oliveira, and thus had the longer stride - 92 steps vs 98 steps, for a step length of 2.2 m vs 2.0 m for Pistorius and Oliveira, respectively (remember that a stride is two steps - I counted steps, but report strides later in the discussion). And the final 100m showed the same pattern - Pistorius' average step length was 2.3 m, compared to 2.2 m for Oliveira.
So, stride length, at least at a superficial level, is not where the advantage came from back then, and it's not the sole explanation now either.
That said, it would be incomplete and false to suggest that Oliveira's leg length should not be the subject of some scrutiny. In the week leading up to that 200m final, Oliveira revealed in an interview that he had recently increased his blade length by 4cm, taking him from a racing height of 1.77m to 1.81m, and he was clearly relatively taller than his rivals.
To understand what all that means, let's consider how the IPC set the maximum allowable leg length for double amputees. First of all, it's not an easy task to do - there is no such thing as a "normal height", and when someone does not have legs, then trying to be specific about how tall they would have been is a complex exercise in dealing with ranges. That's because we don't all share the same limb proportions.
There is an average ratio of say, arms to height, and a similarly average ratio of femur length to total leg length, but these averages don't often apply to elite athletes. One example is Michael Phelps, the world's greatest swimmer, who stands 1.93m tall and remarkably, wears the same length pants as Hicham el Guerrouj, the world record holder in the mile, who stands only 1.75m tall!
That is, a difference of 18cm in height, with the same leg length. Such are the variations between people. One is a swimmer, one is a runner, and they are arguably born to excel in their specific events by virtue of completely different leg to total height ratios. For pages and pages of similarly mind-blowing stats, I would highly recommended David Epstein's book, "The Sports Gene", which is due out this week.
But for now, let's leave it at the fact that the IPC cannot simply say "You should be X cm tall based on your arm length".
Instead, what they have done is establish a maximum allowable height for each double amputee. The image below, which was released in the aftermath of the London 2012 controversy, shows the height limits for the key players in this debate. It invites four thoughts:
Part of the process is discovering how far below the limit the athlete should stop. So for instance, we should be asking how Oliveira knew to stop at 181 cm prior to London, and why Pistorius was at 186 cm in the first place when he could have gone to 193 cm? Why not 189 cm? They had room to play with, but decided not to use it. The answer is that they're optimized at those 'sub-max' heights.
- He is still racing on the same length blades as London (height 181cm). In this case, his improvement is solely due to training, co-ordination and normal development. One can still say he has an advantage, but his improvement is distinct from it.
- He has changed up, and gone to longer legs, then I find it hard to believe that 3 to 4cm (he only has this to play with, it's not as though he can race at 195cm - see table above) can contribute to that kind of performance. This is particularly true given that any increased length must surely compromise the start and bend, and so the effect is even larger. Simply put, it cannot be solely due to running "taller" in 2013
- He has changed down, and found a better "sweetspot" that gives him a better start and bend performance, faster overall, with some accepted reduction in top speed. If this is the case, and he's running at say 179cm, then it's even more of a problem for the IPC and IAAF because whatever they plan to change in their guidelines would need to be even more drastic.
Remember, that night, Pistorius took 49 steps on the bend and 43 steps in the home straight. That is a step length of 2.0 and 2.3 m respectively. Oliveira, on the other hand, had average step lengths of 1.92 m on the bend and 2.2 m on the straight. In a race of absolute stride lengths, Oliveira is second-best.
The key, however, is the stride length relative to body height - someone who has excessively and disproportionately long legs will have a longer stride relative to their height, so you can partially test this 'accusation' by comparing stride length to total length.