My guess is that the forced part of this has little to do with the effects. It's the increased intensity that is providing benefits.
"voluntary wheel running is characterized by rapid pace and short duration, whereas forced exercise involves a slower, more consistent pace for longer periods of time. This basic difference between the two forms of exercise is likely responsible for their differential effects on brain and behavior."
It also did say that both groups ran the same distance, but the non-forced rats did it in more sessions and a faster pace.
a most unpleasant way to die!
> In one study from 2008, rats forced to run wound up with significantly more new brain cells after eight weeks than those who ran when they chose, even though the latter animals ran faster.