i agree, it is perplexing. maybe jay robert's current clinical trial will shed more light on the matter.
i'm making the assumption that he is doing a 2nd trial based on stuff i read months ago, not sure of current status.

if exercise makes you "normal", why do we ever get pd is the obvious question and i'm sure not going to dive into that.

i'd guess i'd like to know how long lasting the affect is in these studies, weeks, months? are some brain cells temporarily stimulated? does some metabolite from muscle cells get into the brain and stimulate neurons?

regardless, i'm still pumping away on my recumbent bike, no permanent affect but i do feel better for at least an hour afterwards.