One thing commuting does for you is that you have rock-hard abs. I swear you could take a 2x4 across my stomach and I wouldn't notice. Forget your fancy machines - ride up and down hills on marbles. The only way to survive is off the seat and control.
I was just reading a bike on MTB and the author was saying that what I ride on is the worst kind of stuff. I think mud is worth - but it is pretty bad. My shoulders and arms are bulking up too by the way.
Yes, there is something very, very wrong with us. Oh, and don't forget bunnyhopping chickens.