[shnikes18]

I don't know an official answer, but when I was in college living in the dorms, I lived in an eight story building, and I would run those stairs (all the way up, down, back up), etc, for 30-45 minutes at a time. That was about the toughest thing I've done - lots tougher than stepping on a bench or on a stairmaster or on that gauntlet. I was in the best shape ever! I wish I still had access to those stairs.

Emily