>"In the range that I was going (5-14%) the angle and the % grade would be almost identical. I also spent most of the three hours while on the machine trying to determine if the motion of the treadmill was the same as walking up a perfectly smooth hill. Initially, I thought as you, the body isn't moving therefore the treadmill was easier. But then I took the example to the extreme, a perfectly 90 degree incline. It then becomes obvious that the mechanics are the same. But I do know that treadmills are easier in two respects; smoother surface and altitude. Can’t do anything about the surface which is why I asked about altitude adjustment."
Greg, I agree slope and angle are essentially the same at low angles.
And that the range of motion your legs go through is the same.
But I can walk 4.25 mph up a "14%" slope on a treadmill all day long and it does not feel like 4.25 mph up 740 vertical feet per mile on good trail.
Being on the treadmill is absolutley better than not being on the treadmill. I don't think it's as good or as much of a workout as being on an actual hilly trail, but we all work with what we have. I'm quite limited, at sea level, on the flats, in a small town, at -18F this morning, simulating a R2R2R hike, and actual stairs are part of what I can do to get in shape.
But my biggest message to newbies is: get some downhill work in. It's the lack of downhill conditioning that has left me hurting in the distant past. Then I turned 45 and got smart.