Originally Posted by cbaronzzi
I have heard this topic discussed before. One argument that stuck in my mind was some suggestion that the strain/pain of hard cycling and accompanying release of hormones, adrenaline, etc. might put your body into the "fight or flight" mode so that any little stimulus could evoke an uncharacteristicly aggressive reaction.
I think that's absolutly the key. How many times have you seen good friends on the brink of throwing punches during a basketball game? One of the reason people enjoy sports is that the emulate thrill of the the hunt and the kill that humans have evolved to crave.