The benefits and tolerance of exercise in myasthenia gravis (MGEX): study protocol for a randomised controlled trial oleh Simone Birnbaum, Jean-Yves Hogrel, Raphael Porcher, Pierre Portero, Bernard Clair, Bruno Eymard, Sophie Demeret, Guillaume Bassez, Marcela Gargiulo, Estelle Louët, Sonia Berrih-Aknin, Asmaa Jobic, Philippe Aegerter, Philippe Thoumie, Tarek Sharshar, the MGEX Study Group