Parkinson's Disease Support Group
Parkinson's disease is a movement disorder often characterized by muscle rigidity, tremor, a slowing of physical movement, and in extreme cases, a loss of physical movement. The primary symptoms of Parkinsons are due to excessive muscle contraction, normally caused by the insufficient formation and action of dopamine, which is produced in the dopaminergic neurons of the...
Actually, this is not the first time I've heard about this. Last year a friend who's dad has PD forwarded me a link with a video on a medical study on pedalling and PD symptoms.
l also can run easily but not walk so well, so my assumption is that little parts of the brain that control movement are affected differently.
Therefore you might be able to do some movement things easier than others