Read this: http://www.rivbike.com/article/clothing/the_shoes_ruse

EXCERPT: "When elite pedalers and lousy rookie pedalers have been hooked up to machines that measure muscle activity during pedaling, the machines tell us this: during normal pedaling at normal cadences, nobody pulls UP on the backstroke the elite/efficient pedalers push down less on the upward moving pedal than the rookies do."

So . . . we don't really pedal in circles after all?

(Yes, I realize who I'm quoting on this, so please take it with a teaspoon of salt since no particular study is cited.)