Shortly after diagnoses I chose high-cadence cycling as my main form of exercise to combat progression of the disease. I bought a stationary exercise bicycle and exercised for about one hour per session (including warm-up and cool-down).
After a few months I found that, soon after starting a session, my right foot would cramp up and turn inwards, in a claw-like fashion. Once this occurred, I would stop cycling and rotate the foot in the air for a minute or two until the cramping disappeared. I could then resume cycling for a few minutes until the cramping returned. It would usually be about fifteen to twenty minutes into the session before the cramping stopped happening.
A couple of years ago I decided to add arm-cycling to my exercise session, and bought a small stationary exercise bike for this purpose. This bike has no seat, its pedals are suited to hand use, and I have it sitting on a small desk. The plan was to keep the exercise session at one-hour duration (30 minutes arm-cycling followed by 30 minutes leg-cycling).
Now for the punch line!
As soon as I changed over to the new session format, the cramping in my right foot stopped happening. I've also tried shorter arm-cycling sessions and seen that even an arm-cycling session of 10 minutes duration is sufficient to prevent cramping during the leg-cycling session. I do my exercise session first thing in the morning, straight after my medication.
Dr. Greger's view on NAD supplementation
Vitamin B2 Deficiency Can Cause B6 Toxicity! PWP Are Commonly Deficient In B2. 
Rethinking Parkinson’s Disease: could dopamine reduction therapy have clinical utility. (The article)
sudden horrible off periods
