Oh gosh, ANY of them would work very well on a treadmill. Volume 8 is ALL hills and it's very hard, but the rest of the workouts incorporate a mix of sprints and hills and/or treks (a fast hill). Volume 2 is my favorite of the shorter workouts and I think you'll be very happy with that one. They're all good and you can't go wrong with any of themI am going to have to use my treadmill for another month or so. I just downloaded Vol 2. What others would be good for a treadmill?


