I only hold the handles when my incline is on 10+ and my speed is a fast walk, I don't want to hurt myself falling!  My favorite is high incline walk for about ten minutes, then a good 2-3 mile run, back up to the high incline walk for another ten.  This is usually after my push/pull routine in the weight room.    Of course, it just has to be this way because running in 100 degree weather for an extended period is a bad idea.  I hate treadmills, but you do what you have to so you can stay non-Ham.