Hello and Welcome to Ask A Doctor service. I have reviewed your query and here is my advice. One of the most frequent reasons that children and adolescents have to stop exerting themselves is because of asthma. Their bronchial tubes start to twitch and narrow when they exercise. There is frequently associated cough. Children and adolescents with asthma can cough at night, cough with emotion(laugh or cry), or when drinking or eating cold liquids or foods. Usually a child or adolescent who has asthma has had eczema as a young child and there is a strong family history of allergy(eczema, hay fever, asthma, hives). If your son is found to have asthma, with proper treatment which include metered dose inhalers(MDIs), he should be able to continue his healthy program of physical activity. Hope I have answered your query. Let me know if I can assist you further.