Does anyone else do an interval training program? I started one on my treadmill several months ago and when I started, I could barely run at 7.5 miles per hour (my top speed). The program is set up so that you run at level 9 out of 10 (with 10 being nearly impossible) as the highest level. So 7.5 mph was my 9/10. Now 9.0 mph is my 9/10. I've been increasing my speeds to keep challenged. If you do any type of intervals, is that what you do?By the way, I was feeling pretty good being at 9.0 until I realized that good marathon runners run 26.1 miles at speeds of about 10 mph. I can barely run for a minute at that speed.