I do not use the word disabled lightly. It is a word that shows there is a very real difference between some and the rest. I am also for anything that diminishes discrimination, including against those who classified as disabled. However, I cannot find myself in support of the idea that people who require assistance from a mechanism should be able compete on equal footing as those that do so with their natural bodies. The story of Oscar Pistorius is a prime example of someone trying to compete unfairly. He is a double-amputee with mechanical legs. It is ludicrous to allow him to compete in a race with people using their natural legs.
The problem is that mechanisms can be modified by simply changing out materials and improving design. They are no representative equal with that of the human body which is allowed. In fact, efforts to unnaturally improve human body performance is specifically against the rules in most sports. Yet, here is someone trying to replace entire body parts with machines! Where is the equal footing here? There is none. If this is allowed and accepted, what is to prevent someone from volunteering to amputate body parts to replace them with machines that might perform better than their nature body? This is less ridiculous than it soudns. One only has to look at some of the unnatural lengths people go through to try to improve their bodies right now with steroids, blood replacement therapy, etc. There's no difference beteen that behavior and that of using mechanisms in place of human limbs in sports.