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That's an amusing conundrum, but it's hardly the main issue.

The real problem is that there is probably almost no way to level the playing field for prosthetic-using and non-prosthetic-using athletes at the professional or elite levels. The biomechanics of competition are intricate and very significant. Tiny differences in body morphology - aside from training or aptitude - can make significant differences in competitiveness. There is likely no way to design prosthetics that (a) accurately mimic the biophysical advantages and disadvantages experienced by non-prosthetic-using athletes, and (b) are not the decisive factor in competition between two such athletes.

The transfer and release of energy in muscles is complicated and of the highest significance: in running, the muscles are stretched and store gravitational potential energy during the weighted portion of the stride, then contract and recover some of that energy (in addition to the much larger active production of energy metabolically) during the propulsive part of the stride. The muscles literally act as springs to some degree; the greater degree to which a runner's personal physiology allows this, the further or faster they can run before depleting their biochemical energy store. Sprint competitions are timed to thousandths of a second; marathons are often decided by time differences amounting to a fraction of a percent of the total time expended. The most minor differences in energy-use efficiency can be crucial.

The springy-leg prosthetics used by runners, such as shown in the picture, store and release energy in a similar way, but not in anything like the same way, as do leg muscles. The mechanics of force against the runner's knee or thigh are different from those in a non-prosthetic leg, and the muscle strain exerted to run with a prosthetic leg is not identical to that involved in using a natural leg. The weight of the leg - and thus the force required to move it - is different, and that force is exerted entirely by the thigh, not the calf, thus tiring the thigh muscles at a different rate. The length of the legs can be arbitrarily set, but that has a huge effect on the leverage through the knee joint. Most important of all, the spring constant of the prosthetic leg is very different from (likely much greater than) that of the non-prosthetic leg muscles, meaning the prosthetic-using runner gets a much larger energy boost from that springiness.

In short, a runner using a prosthetic leg and a runner not using one are simply competing at two different skills. They are not radically different (to the naked eye they both just look like "running"), but I cannot believe that the total energy expended, the patterns of muscle usage and rates of tiring, and other relevant factors, do not differ considerably - and this in a competitive environment in which fractions of a percent can be decisive. Worse than that, there is no way to adjust those differences to make the competition equitable. Of course you can make the legs longer or shorter, lighter or heavier, springier or duller, but what setting of any relevant value is the correct one? Athletic competition at elite levels is in large part the display of minute inherent advantages - a slightly longer reach, slightly faster reflexes, etc. Successful athletes often have noticeably greater inherent abilities at some crucial skill; success is in part a reward for having been born with those inherent advantages (put to good use, of course, through hard work and training). But prosthetic users can buy their physical traits off the shelf. What level of ability should a prosthetic-using athlete be allowed to purchase? Legs exactly equally as springy as their natural ones had been? But what if the athlete hadn't been fully developed at that point? Can they get legs as good as the natural ones they would have developed? But what if they didn't really have the obsessive drive to reach their peak? And how is this competition, anyway, if non-prosthetic-using athletes are always free to use whatever body-building and training regimens they choose to increase their abilities but prosthetic limbs are held to some static definition that permanently fixes their potential maximum performance? From the opposite perspective, if prosthetic-using athletes are allowed to buy any technological advantages that are available (super-light limbs? powered limbs? computerized actively-compensating limbs such as Iraqi veterans are now using?), why should non-prosthetic users bother to compete against them?

Perhaps we could limit competition to matches among, not between, prosthetic-using and non-prosthetic-using athletes only - as with men's and women's tennis. But how would a competition between a below-knee amputee and an above-knee amputee be balanced, or that between a single amputee and a double amputee? Perhaps prosthetic-using athletes should compete only against those with identical injuries. But, not only would that severely limit the competitive pools, there would still be all the above questions about the identicality of advantages conveyed by the exact conditions under which each individual competes. In the end, there seems to be no way to establish competition on an equitable basis between prosthetic-using and non-prosthetic-using athletes, and whatever qualities we would build into the prostheses in an attempt to do so would be arbitrarily set, thus essentially pre-determining the maximum potential of the prosthesis user, which is not pre-determined (or at least not in the same way) for the non-prosthesis-user.

This is not to say that athletics for prosthetic users is out of the question. Obviously, the entire range of non-competitive or informal sports is open to whoever chooses to participate. And competition at non-elite levels would be feasible on reasonably fair terms (the crucial criterion is that differences in competitiveness imposed by the prosthetic technology should be significantly smaller in magnitude than those imposed by the natural variation in the athletes' inherent ability - which for most "weekend" leagues is not going to be much of a problem!). Successful mixed-abilities competition has been seen in team sports in the form of wheelchair rugby (aka "murderball"), in which wheelchair-using athletes are rated as to the degree of their movement impairment and the team as a whole has a total disability quotient it must meet, but no limits are placed at the individual level. Another possibility is that elite prosthetic-using athletes could compete in "open" divisions in which technological innovation is encouraged and there are no or only limited technological constraints - something like Formula 1 auto racing. So there is certainly much room for athletics, and even competitive athletics, on the part of prosthetics-using athletes, including against non-prosthetic-using ones. But the Olympics? I tend to doubt it.

I t is inherent in humans in evry walk of life in which they are in to go beyond their limits.
As it is present in the offical motto of the Olympics adopted by Coubertin "citius, altius, fortis" (latin for "faster, higher and stronger") whichever thing made human limits to be surpassed either by will, talent or technology in sports and games, it´s fair; according to the Olympic´s spirit.
My view is that the measure or standard of uniformity in contest for the partipants engage in the game is just that: "going beyond the limits".

The technology magazine IEEE Spectrum, for which I work, ran a long feature article 18 months ago asking the broad questions addressed here, but with more input from top biomechanical engineers. I asked our senior news editor Bill Sweet, who worked on the story, and here's what he has to say about the current controversy:

"Just from a technical point of view, could passive prostheses-which, by definition cannot generate energy but can only store and release it-give Oscar Pistorius an edge over able-bodied athletes? Experts were divided on the question, but our article still provides the most in-depth discussion of the purely technical dimensions of this extraordinarily complicated case (http://www.spectrum.ieee.org/print/2189). To be sure, if Pistorius does make the South African team, any decision as to whether he should be allowed to compete in the Beijing Olympics will not be taken purely on scientific grounds-and perhaps it shouldn't be. But this much is certain: International athletics officials are praying that Pistorius won't run fast enough to qualify, sparing them what must seem, to them, a no-win moral choice."

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