Children’s arm soreness may be related to lactic acid buildup, muscle strains, common cold, and so on. 1. Lactic acid buildup: Children’s recent over-exercise, such as playing table tennis or badminton, leads to a large production of lactic acid in the muscles, which stimulates the muscles to produce soreness. 2. Muscle strain: It may be when the child is doing push-ups or other sports. Overstretching or strenuous activities cause muscle strain and arm pain. 3. Common cold: As inflammatory factors invade the bloodstream during a cold, they release inflammatory mediators, prostaglandins, etc. causing muscle soreness. Some of them may only have the symptom of arm pain. Children’s arm pain can also be seen in other causes, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions to carry out relevant examinations, with the help of the doctor to clarify the cause, and targeted treatment or treatment.