This dialog reminded me of a rumor I heard awhile ago about trying to measuring efficiency of Lance Armstrong (competitive cyclist). A brief search gave me [1], but I'm sure there are better articles out there. My big take away is that even with modern technology and understanding there is just so much we still don't fully understand - especially about the human body and processes.

[1] http://www.sportsscientists.com/2008/09/coyle-and-armstrong-...