Four-year-old baby coughing on strenuous exercise, and viral colds, bronchitis, bronchial asthma and other factors. 1. viral cold: due to viral infection and cause runny nose, nasal congestion, pharyngeal swelling and pain in the symptoms, not timely treatment will lead to aggravation of the condition, which will affect the respiratory function, so that strenuous exercise to produce coughing. 2. Bronchitis: bronchial infection by bacteria, viruses and other pathogenic microorganisms, will occur after the bronchial mucosal congestion and edema and other inflammatory reactions, and strenuous exercise will enhance the inflammatory reaction of the bronchial tubes, so that cough symptoms. 3. bronchial asthma: strenuous exercise will lead to the body of the choline nerve secretion and cause excessive bronchial spasm, thus causing coughing performance. Four-year-old baby coughing on vigorous exercise, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.