You would know if you had a SFEMG. During an EMG, they don't need your help. They do in the SFEMG. You have to, for example, lift up the fingers in your hand while they do the EDC muscle in the hand/forearm. A similar flexing of muscles is done in any area tested.
I was being
really sarcastic about the exercising of swallowing muscles!

Only those with neuromuscular issues would need to do that. And if someone has MG, exercising will only minimally help. Only more acetylcholine (or other treatments affecting the underlying autoimmune process) will help!
In medicine, usually the simplest answer is the right one.
Go ahead and let them repeat the blood tests. Antibodies fluctuate over time.
They need as much evidence as they can get. So do you!
Annie