As the mainstream "analysis" of the amazing Michael Phelps inevitably gets silly, the boys at Science of Sport offer perspective:
Beware the mythological physiology
One thing that we can be sure of though, is that as sports fans we must be careful not to portray Phelps as being a physiological superman. We saw this happen with Lance Armstrong where sports pundits and even Phil Ligget and Paul Sherwin kept the myth alive by gushing about Armstrong's larger than normal heart, bigger than normal lungs, lower than normal lacate concentrations, and his remarkable weight loss after cancer. None of these characteristics were ever measured or proven, and in fact his "remarkable weight loss" was disproven in a scientific paper in which his weight was measured yearly both pre- and post-cancer, revealing that actually he weighed slightly more post-cancer.
The reality is that the usual explanations are completely unable to explain why one athlete is dominant - when you put these athletes in a lab, there is NOTHING that can be measured that proves why one athlete is superior to another. In cycling studies, for example, a Pro-Team will be measured, and the best guy is often the one with the smallest heart and lowest VO2max!
So is Michael Phelps a great athlete? Indeed. Does he train hard? Most certainly. Harder than his competitors? Perhaps, yes. Is he motivated? Maybe more than anyone else in the pool. But this speculation about how his toes are so long that they wrap around the starting blocks and give him an advantage? Or that he is double-jointed in his knees and that gives him a better dolphin kick? Or that his heart is extra large to pump blood (so are the other 7 guys', incidentally)?
Come on, people, let's keep it real here. Until those things are measured and shown to be true, let's just say he is a great athete with a strong will to win who so far has done everything right, including wearing a Speedo LZR Racer (and he has even been a bit lucky, too).
