just a small study but food for thought, aerobic/weight training exercise has other non-pd benefits.

https://nwpf.org/stay-informed/news/...0%99s-disease/

this was a retrospective study, patients described their activities. after re-reading this study, i wouldn't have posted it except to say that it confirms exercise doesn't have to be strenuous to help.

one can speculate that those that are busy all day long are also better medicated and take their drugs when they're supposed to so they "work at" being active. lots of variables here.

This was an interesting study, but, as you said, leaves a lot to speculation. There are some serious design flaws. One of the problems I had was using the CHAMPS questionnaire to distinguish between the amount of time for strenuous vs. everyday activity. It's not that difficult to estimate the amount of time one spends playing golf, tennis, running, etc. ( all questions on the CHAMPS). However, it is much more difficult to give accurate weekly hours for everyday activities, like reading, working at a computer, leisure walking, visiting friends, doing basic housework, etc. Still, it would be nice to see a controlled study test the hypothesis.