Originally Posted By: bws48
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I have spent a lot of time on treadmills, and noticed something about them---it seems that you go faster on a treadmill than you can actually do on even flat streets. I noticed that in the gym, I could do 4 MPH for at least a half hour, according to the machine speed setting, but in fact on flat terrain outside, the best I could sustain for the same length of time was about 3.7 MPH. The cardio effort seemed roughly equal to me.



I set the treadmill for about 3.5% grade to account for the difference between the treadmill and "outside." The motor running the belt underfoot is equivalent to getting a downhill assist.