How High Should I Adjust My Treadmill Incline?
The assumption under this question arises from a study (Jones, Journal of Sports Science, August 1996) that showed that a 1% treadmill incline offsets the lack of “wind” effect that occurs when moving forward over ground, making running on the treadmill with its incline set at 1% roughly equivalent to running over ground.
However, the Jones study found this equivalent only when his subjects ran at speeds of a kilometer is less than five minutes. That makes sense that a fast pace would produce that sort of resistance, but that’s much faster than most people will run.
It turns out that the biomechanics of running on a treadmill are not significantly different than those of running over ground. According to published research, gaits, joint movements, and power trajectories were essentially the same in both forms of running. See the study here: http://www.ncbi.nlm.nih.gov/pubmed/18460996
It has often been said that treadmill running is easier because the treadmill is actually moving you forward, while in over ground running you need to do that yourself. However, this 2008 study places this in doubt. Of course, the “give” of the treadmill’s cushioning, as well as the length of the runner’s stride also affect the perceived and real difficulty of the running both on a treadmill and over ground.