Left to right: Britain's Jonnie Peacock (Image: Adrian Dennis/AFP/Getty); Alan Fonteles Cardoso Oliveira of Brazil (Image: Julian Finney/Getty); Oscar Pistorius of South Africa (Image: Eddie Mulholland/Rex Features)
Will tonight's Paralympic men's T44 100-metre final settle the score between Olympic hero Oscar Pistorius and Alan Oliveira, who beat Pistorius in the T44 200-metre race earlier this week? Pistorius has made it clear that he considers Oliveira's longer leg blades give him an unfair advantage by increasing his stride length.
But things aren't that simple, says Steve Haake, head of the Centre for Sports Engineering Research at Sheffield Hallam University in the UK: "It's very unclear what advantage or disadvantage different blades have." In particular, there's no evidence that longer blades are better, he says.
If blades are made longer by increasing their mass, then they will be heavier, making it harder to run. But if blades are made longer using the same mass, then they will be thinner, which will reduce their springiness - making them less efficient for sprinting. Longer blades also have an adverse effect on the angular momentum of a runner's stride, moving the mass further away from the rotational centre of the knee.
What about Team GB favourite, Jonnie Peacock? Peacock, also competing in tonight's final, uses a single blade, which means he has to compensate for an imbalance when he runs. While the blade on his right leg is highly efficient at returning energy each stride, his left foot will absorb energy. "Two blades are more efficient in terms of energy absorption," says Haake.
But we can expect Peacock to start more quickly, as twin blades are not optimised for slower initial speeds. Their physical advantages kick in around the 60-metre mark, says Haake, for the final sprint to the finish line.
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