I found this little gem inside a mid-nineties issue of Bicycle Guide magazine. This was back when cycling publications had useful articles that weren't about Lance Armstrong's Le' Tour preparations and Jan Ulrich's weight problems.
Ever wonder which muscles fire when - during your pedal stroke? Here's a chart of the clinical analysis.
Click the image for a printable/readable size.
Article was last edited on Wednesday, August 6th, 2008 @ 4:31 PM
This is also good.
http://cozybeehive.blogspot.com/2006/10/what-muscles-are-you-using-to-pedal.html