Study: Biking Restores Brain Connectivity in Parkinson's
Joyce Park stashed this in Science
It's not just biking, it's specifically being forced to bike much faster than the patient wants to. The way this was discovered is one of those great stories about serendipity in science: a doctor and a Parkinson's patient rode a tandem bike across Iowa, and she showed strong improvement afterwards.
Biking much faster than we want to can be dangerous.
I'm guessing a stationary bike is good for achieving this effect?
I'm not sure, I don't use the stationary bike very much but I don't think normal ones can force you to go faster. They increase effort by going HARDER, but that just makes it more likely you'll come to a complete stop because it's gotten too hard.