Friday, August 8, 2008

Cheetah Feet

Cheetah feet replacement for runners without lower limbs seem like they might give a runner an advantage over one with natural limbs. The carbon fibre limbs are passive springs with a greater return than human soft tissue. The study detailed on the ABC's Catalyst (Why don't we have more good science shows in Australia?) indicates however that since they lack calf muscles, the artificial limbs cannot generate the same propulsive force as a biological limb. Runners wearing them are therefore not at an advantage when compared to fully bio-limbed competitors.

I've raced against a cyclist with an artificial limb clipped to his pedal at what would have been the heel (i.e. the limb had no foot). I guess this allows him to press and raise the pedal with his thigh, gluteus and back which do the work even in bio-limbed riders. The calves of cyclists may look impressive but apparently they do not apply much driving force, they just stabilise the foot. Steve Hogg has gone so far as to slide the cleat on bio-limbed riders back towards the arch of the foot instead of under the ball. He claims it gives an increase in power whilst in the saddle, even if you lose agility out of the saddle. I.e. this position is for flat TTs rather than sprinting or climbing out of the saddle.

So, if an athlete with a prosthetic limb turned up to compete on a mechanically-actuated limb, could it be tuned to mimic biology and provide an equal playing field? How would this be determined? I suppose it is strange how men and women compete separately but short high jumpers are not given a special category in which to avoid needing to compete against taller athletes. Heavy-weight boxers do not compete against fly-weights. Weird! Who decided in some sports to have categories but not in others? What basis did they use for their decisions?

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