[hlnx1]

A common recommendation is to set the treadmill to 1% incline to mimic outdoor running. The idea comes from research showing that the absence of air resistance makes treadmill running slightly easier, mainly at faster speeds.

• At easy speeds, the difference between treadmill and outdoor running is small for most people
• At faster speeds, air resistance outdoors becomes more significant, so a small incline compensates
• Treadmill calibration varies; the displayed speed is not always exact
• Heat builds quickly indoors; a fan helps keep heart rate and effort realistic

Related: running economy.

Do you use incline on the treadmill, and how do you compare treadmill and road paces?

[hlnx1]

For easy runs, 0-1% incline is fine and comfort is what matters. For threshold or interval sessions where you want effort to match road paces, 1% is a reasonable default. Use heart rate and perceived effort to check that the sessions feel similar.

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