Tara's stride is too long to trot or run on the only human treadmill I have access to. I think it is an inexpensive one with ~4' belt. I can only walk her on it. She is 23.5" at the withers (yes, shoulders) and 64 lbs. She does not have a long reach at all, either.
Training him to walk on the treadmill can take a little time and can be a little extra mental stimulation in addition to the physical benefits. It wore Tara out pretty well till she got used to it even if we only worked on it for 5 minutes at a time.
Tara NW1 CGC - GSD 2008
Suli - DSH 2006