Man, my butt hurts!

Part of the marathon training schedule that I am using has a once-a-week cross-training day in it.  The idea is to do something that is cardio training but not as hard on the body as the contant pounding that running is.  I have chosen to ride a bike at a the local fitness center.  Today was an hour and I very aware of some muscles that I was not aware of when I got up this morning.  I rode for the hour, made it 15+ miles without actually moving, and burned 630+ of the calories that I consumed yesterday.  It was a long hour but at least they have televisions on the bike equipment so I was able to catch up on the latest news.