Two posts today:
- The IAAF report on Oscar Pistorius is released, with the finding that Pistorius has a “clear mechanical advantage” over able-bodied athletes.
- Discussion, insight and review into the history of this debate, as well consideration of Pistorius’ intention of challenging the IAAF ruling.
Oscar Pistorius banned by IAAF – carbon fibre blades offer “Clear mechanical advantages”
After two postponements, the IAAF have today released the report based on their testing of Paralympic athlete Oscar Pistorius. The details of the report, which we’ll do our best to get hold of, are enough for the IAAF to prohibit Pistorius from competing in the able-bodied Olympic Games later this year.
You can find a copy of the IAAF press release here. If any more information or data emerges, we’ll do our best to make it available. But briefly, our analysis of the IAAF results is found below. There is obviously a lot more to the theory behind these results and the discussion, but honestly, it’s all been said before – about 6 months ago. So the results of this testing merely confirm what was being said back in June 2006. Therefore, we won’t go into massive detail in this post, but rather redirect you to this post, where the scientific theories were evaluated.
1. Energy consumption: 25% lower with Cheetahs
The first important finding of the IAAF study is that during running at a given speed, Pistorius uses 25% less energy than the runners he was compared to.
Why is this significant?
It suggests that the Cheetahs are far more efficient than the human limb. In fact, that point was argued extensively last year, and the theory is that running on the Cheetahs will save energy investment. They reduce the demand for muscular work, and this in turn, enables Pistorius to run faster before potentially detrimental physiological changes occur and force him to slow down. In fact, this was EXACTLY what would be predicted.
Having said that, the magnitude of the difference is enormous. I had thought perhaps a 5 to 10% difference (which is still massive), but to have a 25% reduction is quite astonishing in terms of the advantage it would confer.
2. Energy return: Never seen before levels of energy return
Secondly, the research found that the carbon-fibre Cheetahs returned energy during running at levels never seen before in the human ankle. That is, the Cheetahs were able to store and release far more energy than a human leg ever has been measured to do. In fact, in a related finding, it is reported that the returned energy from the prosthetic blade is close to three times higher than with the human ankle joint in maximum sprinting.
Why is this significant?
This is part of the mechanism for the first finding of lower energy use in Pistorius. In other words, Pistorius is investing less energy, and having to work less hard than able-bodied runners to sprint, because his legs are providing greater returns. So not only is he investing less energy, he is getting more out. Once again, the consequence of this is that he can run at the same speed with less energy, and hence is able to run faster than his physiology would allow him to.
3. Less vertical motion during running
The third key finding is that Pistorius, running with the Cheetahs, displayed a much lower vertical oscillation than the able-bodied runners during sprinting. Also, the vertical impact forces were lower in Pistorius compared to able-bodied runners.
Why is this important?
As with the first finding, the lower vertical movements means less energy is lost during landing and less used during the push-off phase of running. It has long been believed in the scientific literature that when you are running, a more economical runner will have a reduced vertical oscillation compared to an uneconomical runner. The Cheetahs provide this economy, and this contributes to improved performances.
4. Energy loss is much lower in the Cheetahs than the human leg
The fourth key finding is that the amount of energy lost during the stance phase of running was only 9.3% with the Cheetahs, but was 41.4% in the human ankle/leg. This difference, greater than 30%, is responsible for a large mechanical advantage compared to the human leg.
Why is this important?
Once again, it means that the physiological and metabolic work that is required of Pistorius is much lower than that of able-bodied runners, because he’s losing far less energy. In order to run at the 400m speed, kinetic energy must be “created” through muscle contraction in all runners – the burden on the able-bodied runners is far higher, since they lose more energy. And, as seen in Finding Number 2, they also recover far less energy (three fold difference), adding up to a massive advantage for Pistorius – this is again part of the mechanism for the lower energy cost of running.
The sum of the findings
The sum of all these findings is that the Cheetahs contravene IAAF rule 144.2, which is that a technical device may not be used if it aids performance. As a result, Pistorius has been prohibited from using them, which ends (for now) his chances of competing in the able-bodied Olympics.
Pistorius has however already said he’ll challenge the ruling and has come out in a hostile attack on the IAAF and researchers for leaked comments. In addition, he has suggested that they have not assessed enough variables to make their decision.
The problem with this is that even if they do test another variable or two where he does not have an advantage, he now has to overcome a 30% advantage regarding energy storage, and 25% advantage regarding energy use during sprinting.
The sheer size of these PHYSIOLOGICAL differences is staggering and one can only speculate as to what sort of performance advantage that gives him in a 400m race. 5 seconds? 10 seconds? It’s very difficult to relate performance to physiology, because so many factors are integrated to produce a 45 second 400m race. But one thing that is for sure – we’re not talking milliseconds here, it’s a “considerable” advantage, to quote Prof Brueggemann.
But Pistorius has promised to challenge, and we discuss the history of the debate and Pistorius’ possible challenge in a separate post, which you can read here.
We’ll get more insight on these results as soon as we can!