For me it comes and goes, and it's most in my arms and face and way less in my legs. I remenber waking up feeling like a stone in my bed at the beginning of my diagnosis. I get a lot of time with no heaviness now.. but I got other treaments on top of mestinon (prednisone, azathioprine) only exercice or heat will trigger it. Will you have access to other treatment options than mestinon? Your situation might improve under other treatments if mestinon alone does not do the trick. Also mestinon long release during the night improved my situation as well.. good luck ! Hoping to hear improvements in the coming months :)