The reason for the pain at the root of the thigh after swimming, there are two main aspects: First, before swimming did not adequately do preparatory activities, coupled with the water temperature is cooler, there may be a thigh muscle strain. If the pain is not severe, just need to rest fully, the first two days of cold compresses after hot compresses can improve the symptoms. If the pain is severe, you can use topical Yunnan Baiyao spray, oral non-steroidal anti-inflammatory drugs. Second, because of swimming thighs for a long time, high-intensity exercise, resulting in muscle strain. Soft tissues produce sterile inflammation if it is not too serious, it can be improved by just taking sufficient rest. If the pain is severe, you can take non-steroidal anti-inflammatory drugs, or go to a regular hospital to perform physical therapy treatment.