Science: What Treadmill Gradient Simulates Outdoor Running?

Dick Moss, Editor

You have students who run on the treadmill at a local fitness center and ask you what gradient they should use when training (elevation of the treadmill platform to simulate uphill running). Good question.

Fortunately you now have the answer, thanks to a recent study. Tell them to use a 1% gradient if they want to simulate outdoor running.

The Study
The experiment, conducted at the University of Brighton in the UK, acknowledged that treadmill running is easier than outdoor running because it involves minimal air resistance. Outdoors, the body must displace air as it moves. Indoors, the body remains in place while the “ground” moves, so no air is displaced and air resistance is minimal.

The study set out to determine what the difference in energy cost actually was, and how much to adjust the treadmill gradient to equalize the difference. The researchers measured V02 max at a number of different running speeds (from about 5:20 to 9:10 minutes per mile) and gradients (from 0 to 3%) for six minute time periods, compared to similar efforts outside on flat ground.

Results
It was found that at running speeds from 5:20 to 9:10 minutes per mile, the effort used when treadmill running is the same as running outdoors if they use a 1% gradient.

References
1. Trevor Clinger, The Top 4 Treadmill Workouts (Kindle Edition),
Amazon Digital Services, 2014.
2. Andrew M. Jones, Jonathan H. Doust (U. of Brighton, UK), Journal of Sports Sciences, Volume 14, Issue 4, 1997.

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