dave6768 wrote:
There is no doubt that raising the incline to 10% will give a tougher workout. It's tougher only because you have to lift your legs higher, not because your are moving your entire mass up an actual 10% incline. Go run an actual 10% incline on a road and see which workout is way tougher. Don't get me wrong, a workout on the treadmill is better than nothing, but it's not 100% the same.
Edit: ** For a treadmill that maintains a constant speed while in use.