what makes the stationary pedaling so appealing is you can do it night or day, rain or shine, even if you have balance problems and i think it's low impact, even though i know pd'ers in great shape that get back, hand, elbow pain at times if they stand up while pedaling.
anecdotally, i was diagnosed at the end of 2001 and played on a men's soccer team until 2005 and after a soccer game i felt like i didn't have pd for maybe a day. now i can jog but have too much leg/foot rigidity to kick a soccer ball with much power so don't. after i stopped playing soccer stopped vigorous exercise but started up again in 2009(?) when jay alberts published his forced exercise study and got a recumbent bike. can't say i get the same benefit that nan little got/gets and i find it somewhat boring but i can get a workout on it even on a "bad" pd day. also use a portable stair stepper from XISER, pricey but 5-10minutes on it can be exhausting.