Sorry if this has been covered before.

People always say a 60 min trainer ride is almost the same as a 90 min outdoors ride, or 2 hours of Spinervals indoors is equal to 3 hours outdoors. (Something like that)

Does this theory apply to the treadmill too? If I run 1 hour on a treadmill, what will that equate to outdoors?

Any ideas? Thanks!