Thank you, NYTimes, for clarifying something I have always wondered about: how does running outside compare to running on a treadmill?
A number of studies have shown that in general, outdoor running burns about 5 percent more calories than treadmills do, in part because there is greater wind resistance and no assistance from the treadmill belt. Some studies show, for example, that when adults are allowed to set their own paces on treadmills and on tracks, they move more slowly and with shorter strides when they train on treadmills.
I will say that in my case outside running burns more calories because I go much farther. Running on a treadmill bores me to death, so I don’t do it.