cold feet thows off EMG test?

Yes. When I was tested (EMG) at University of Chicago they used a hair dryer to warm my skin in the entire area they were testing. They constantly kept checking my skin temp and would get the hair dryer out and warm me up.
They said some of the really nice facilities have special rooms that keep your skin temp regulated.

🙂 Yeah, they want you warm for good signal.. I think this is where a lot of variability with the testing of conduction velocities… Getting tested in the winter coming in from sub zero temps and going into a cold room makes for tricky responses….