Hi. I hope I don't make this too complicated.

In MG, antibodies attack the neuromuscular junction, destroying muscle receptors. It's the place where the nerve meets the muscle. Acetylcholine, kind of like our bodies "muscle gas," then doesn't have as many muscle receptors to go into.

When acetylcholine is done "feeding" our muscles with energy, there is an enzyme called acetylcholinesterase that comes in and "mops up" the acetylcholine. Mestinon, one of the drugs used for MG, helps "fend off" the enzyme and keeps more acetylcholine in our neuromuscular junction longer, so we can use more of it.

When your body gets hot from a fever from an infection or hot weather or anything else that heats the body up, that little enzyme gets much greater in number. That also happens when we get too cold. The enzyme "eats up" even more acetylcholine. Then we have even less muscle gas and our muscles get weaker.

People without MG have this happen too but they don't notice it as much. They may get "tired" after being out in the heat for too long.

Just stay the heck out of the heat AND humidity! Oh, the humidity makes it worse because when it's humid, your body can't sweat. Sweating cools off the body. So if you can't cool down, you can get even worse.

Annie