## 3 Results
### Myasthenia Gravis  
Myasthenia gravis (MG) is an autoimmune disease in which antibodies bind to ACh receptors in the postsynaptic membrane at the neuromuscular junction [19]. Given its pathophysiological characteristics, MG is characterized exclusively by motor symptoms that tend to be exacerbated by physical exercise. Thus, fatigue appears as a consequence to repetitive muscle contraction. In view of these particular characteristics of the disease, the question of the benefits of engaging in physical exercise has been the subject of considerable controversy. However, reviews of the relevant literature indicate that, as in the case of other neuromuscular disorders, physical exercise can be beneficial, as it improves muscle strength and volume and is also safe [20; 21]; however, it has little impact on fatigue. This finding might imply that the fatigue experienced by MG patients is not exclusively due to muscle factors but also encompasses other factors, most likely psychological. In light of the above-mentioned considerations, it is imperative to approach patients with MG with extreme caution regarding their involvement in sports activities. Only four cases of patients with MG involved in competitive sports activity were identified during the review of the relevant literature. The first one was published in 2000 and reported the case of a 17-year-old college football player [10]. A diagnosis of seronegative generalized mild MG was made, and the patient was started on a course of prednisolone, with satisfactory results, although there was some inconsistency in his compliance with the treatment plan. He continued to engage in training sessions with the team, yet was prevented from participating in competitive matches. He experienced eyelid ptosis after vigorous exercise (weight lifting) that was easily relieved after a few minutes of rest. In his senior year, he participated fully in football practices, but finally decided to quit, due to back pain unrelated to MG. The authors highlighted two points: the lack of guidelines regarding the safety of sport activity in MG and the Walker phenomenon [22], which is the delayed appearance of weakness in a muscle distant from those being exercised (eyelid ptosis after weight lifting). The other two cases describe patients that completed long runs, a marathon and an ultramarathon, even though they were diagnosed with MG and were under treatment. The first case [11] describes a 36-year-old woman who experienced fatigue while running prior to receiving an MG diagnosis. However, despite receiving a confirmed diagnosis, the patient continued to engage in running activities and even improved her personal marathon time, although she experienced slight difficulty at the beginning of a run and towards the end of the pyridostigmine dose. Her disease remained stable through the years under cholinesterase inhibitor treatment, encountering only brief and mild deteriorations. Quality of life was overall improved. The second one [12] reports a case of a 52-year-old man who had also initiated a running routine prior to being diagnosed with MG. Following MG diagnosis, he similarly continued to engage in physical activity. He participated in five ultramarathons. His symptoms were recorded during the fifth one of a 220 km distance. He complained of fatigue after running 30 km during the first stage, facial grimacing and difficulty with speaking at the end (37 km). Other runners observed he had difficulties in breathing and swallowing and he reported generalized muscle weakness on uphill sections. All symptoms subsided easily and quickly with rest and increased pyridostigmine dosing. He successfully completed the race finishing in 35 th place among 65 athletes. Finally, a last report [13] described a professional cyclist with generalized myasthenia gravis who successfully returned to competitive cycling after thymectomy and aggressive medical and rehabilitation treatment.