New Belt
The belt I have is new and clean, and the static shocks are quite shocking! I even tried to ground myself, with a wire from the treadmill to me-and shocks came every 4 seconds. Needless to say, I threw away the wire. Would a single surge protector help? I'm curious , and will purchase...
Static electricity
Alot of what your saying is probably correct, plus friction caused by the running shoes will create the shocks. However, I am sure that the material of the sneakers, such as the nylon used, increase the presence of static shock.