The fatigue after running may be caused by fatigue, myasthenia gravis, low blood sodium, low blood potassium, hypoglycemia and so on, which need to be analyzed specifically. 1. Exhaustion: If the patient has not run for a long time and suddenly performs strenuous exercise, a feeling of fatigue will arise. When the amount of exercise is large, the body is in a state of exertion, so the symptoms of weakness can appear, and can be relieved after rest. 2. Myasthenia gravis: the clinical manifestation is that the affected skeletal muscle is very easy to fatigue, after short-term contraction, the muscle strength decreases obviously, and fatigue occurs after exercise, which is related to the autoimmune reaction in neurotransmitters. 3. Low blood sodium, low blood potassium, hypoglycemia: when running, there is a relatively large amount of sweating, resulting in excessive loss of potassium and sodium, which leads to symptoms of fatigue; or when the amount of exercise is relatively large, due to the increase in energy consumption, which can easily lead to hypoglycemia of the body to appear in the case of this symptom. If you are not relieved after running, you should go to the hospital in time to have a checkup and get a clear reason for the treatment.