I found this thread in the archives by searching on the word "lymph". I was hoping to learn why exercise, particularly high-cadence cycling, can sometimes help the symptoms of PD so dramatically.

I subscribe to the theory that PD most commonly has microbial etiology. The brain in PD may be less able to cleanse itself of infection and inflammation -- and if the glymphatic system is the means by which that cleansing takes place, then it seems to make sense to increase the flow of lymph through that hydraulic system, which is pumped by body movement. A PD patient who doesn't move much, probably has slow glymphatic flow. High-cadence cycling should increase the flow of lymph through the glymphatic system. This sounds like the perfect recipe for cleaning the brain; a clean brain may be better able to heal itself.

Equipment like the Theracycle can provide either resistance or assistance for pedaling. Hypothetically, "if" high-cadence cycling improves brain cleansing solely by the speed of its pumping action -- meaning that speed rather than effort may be the important factor -- then it may not matter whether we use assistance to achieve that speed. Hypothetically, even a paraplegic PWP could achieve the necessary speed, by using equipment that assists. What do others think about this? Many thanks!