The claim

“We aren’t racing a fair race.”
Oscar Pistorius, 2 September 2012

The background

Paralympic icon Oscar Pistorius’s defeat in the T44 200m final last night came as shock – not least to himself.

Brazil’s Alan Oliveira came from behind to surge past South Africa’s “Blade Runner” in the final straight, an achievement that provoked an angry outburst from Pistorius after the race.

He said: “The guys’ legs are unbelievably long. Not taking away from Alan’s performance, he’s a great athlete, but these guys are a lot taller and you can’t compete (with the) stride length.

“You saw how far he came back. We aren’t racing a fair race.”

It’s not just sour grapes. Pistorius had repeatedly questioned the length of some of his competitors’ J-shaped prosthetic legs before the final, blaming International Paralympic Committee (IPC) rules for allowing athletes to “make themselves unbelievably high”.

He has also singled out US sprinter Blake Leeper as having suspiciously long blades, saying: “It’s a problem because the rules allow the guys to make themselves a lot longer than what they would have been had they not been double amputees.”

So there are a number of accusations here: the athletes are using prosthetics to make themselves taller than they would be if they were not disabled; the IPC allows them to get away with it; the longer stride length gives them a significant advantage. Let’s take them one by one.

The analysis

Were Oliveira’s blades longer than Pistorius’s?

We don’t know, but there’s no reason why they shouldn’t be, since blade length varies according to how tall the athlete is estimated to be.

The International Paralympic Commitee measures every athlete and gives them a maximum blade length, but it’s different for every competitor to reflect how tall they would be if they had legs.

First the athlete’s forearm is measured. This is a classic, relatively accurate indicator of height. (Your foot’s about the same length as your forearm too. Try it – isn’t nature wonderful?)

The next measurement is from the middle of the chest to the tip of the middle finger. Different formulae are used to turn those numbers into estimates of height, then an average is taken, with an extra 2.5 per cent added, which would give a 6ft runner an extra 1.8 inches.

When the athlete puts on the prosthesis he must be no taller than that number. A permanent record is kept for each athlete.

As long as Oliveira’s blades are not so long that he exceeds the maximum height laid down by the IPC, he’s in the clear, and the body insists it checked his blades last night before the race and gave him the nod.

Pistorius has hinted that there may be something wrong with these checking procedures, the dark implication being that people could cheat by switching to an illegally long prosthetic at the last minute. But there is no evidence that anyone has done this.

Are longer blades better?

Yes and no, according to prosthetics expert Bryce Dyer from Bournemouth University. A sprinter with longer blades will tend to finish faster, as the blades store more elastic energy, enabling him to maintain speed while using less energy.

But longer blades usually mean a slower start, as the athlete has to expend more energy to get up to top speed.

Mr Bryce told us: “Oliveira had a terrible start. His legs are so springy that they compress when he comes off the block, whereas Oscar’s legs are much stiffer and stronger.

“But towards the end of the race having a softer springy step is better. Oliveira is basically banking on having a stronger finish, and that’s exactly what happened.

“Both of them will know this. You can’t have a strong start and finish. It’s one or the other, and it looks like Pistorius backed the wrong horse.”

This trade-off between a hard start and an easier finish with prosthetics is in fact exactly the point that Pistorius’s lawyers made when they challenged a 2007 ruling by the International Association of Athletics Associations (IAAF) that initially banned him from competing in the Beijing Olympics.

Sports scientists tested him on the running track and found that he could maintain the same speed as a non-disabled athlete while using 25 per cent less energy, which was regarded as a significant unfair advantage.

But Pistorius successfully challenged the ruling, saying the analysts had only measured his gait while running at full speed and had not taken into account the mechanical disadvantage he suffered at the start of the race and during the acceleration phase.

What about stride length?

Pistorius has suggested that this is the key issue, but running fast must be a lot more complicated than just taking long strides, otherwise every sprinter would be a lanky Usain Bolt rather than a stocky Yohan Blake.

In any event, we know that Oliveira’s stride was shorter than his rival’s last night because he took more steps – 98 strides to 92.

Oliveira took 52 steps in the first 100m then 46 steps down the home straight, according to Dr Ross Tucker from The Science of Sport. That’s more strides in both halves of the race than Pistorius (49 and 43), so the Brazilian’s stride length was shorter all the way through.

Mr Bryce said Oliveira’s victory was attributable to faster turnover rate – the speed at which he switched his legs – rather than length of pace.

This, according to some scientists, may be the key to how amputees are able to run so fast. The lighter weight of the prosthetic means the legs can be swung backwards and forwards more quickly than a non-disabled athlete can manage.

Oliveira appears to have done this better than Pistorius.

It has to be said that sports science is a relatively new discipline and even the world experts admit we still don’t fully understand the mechanics of how Olympic athletes run, let alone Paralympians.

Some analysts have suggested that the length of time the runner’s foot stays on the ground is key to generating speed, which might mean that longer blades give you an advantage even if they don’t lengthen your stride.

Why can’t Oscar change to a longer blade?

In theory, he can if he wants to, as long as the blade doesn’t make him exceed the maximum height stipulated by the IPC.

It has been suggested that Pistorius cannot legally change prosthetics because of the ruling finally made by the IAAF to let him complete in the Olympics.

But we’ve established that this is not the case. Pistorius has to use the same pair of Flex-Foot Cheetah blades approved by the IAAF in non-disabled competition, but that does not apply to the Paralympics.

It’s unlikely that Pistorius would want to start swapping his blades around because he’s publicly stated in the past that his achievements are about training not technological advancements. His website proudly states that his Cheetahs have “changed very little since 1997″.

The verdict

Whether Oscar Pistorius likes it or not, we may be seeing the beginnings of a kind of arms race in the sporting technology that makes the Paralympic Games possible, with athletes making small technical adjustments to give them the best possible advantage, as in other sports.

That may be unfortunate or inevitable, but there is no evidence that Oliveira has broken the current rules on blade length, or that the rule itself is unfair.

Our understanding of the mechanics of blade running is still in its infancy, and it’s likely that more studies will follow as athletes like Pistorius come to greater prominence.

We ought to remember that the decision to let Pistorius compete in the Olympics wasn’t the final word on the subject. The Council for Arbitration in Sport did not positively say that blades gave him no advantage over the non-disabled – merely that there was insufficient evidence.

Many experts predict that athletes with prosthetics will soon be breaking non-disabled records, which will no doubt reopen the whole debate about unfair advantage, but will also make for exciting television.

By Patrick Worrall