It's pretty clear that "forced" in the context of the experiment is being physically forced to do more work, not being "forced" like being forced to eat your vegetables.
I think it has something to do with external energy being added, and the subject not having control over the speed.. I don't know if a treadmill really meets this criteria. I think you would have to be physically strapped into the treadmill :P
I think it has something to do with external energy being added, and the subject not having control over the speed.. I don't know if a treadmill really meets this criteria. I think you would have to be physically strapped into the treadmill :P