Muscle spasms are very common when swimming, for the following reasons: 1. When people are on the shore covered by clothing, the body surface temperature is relatively high, once in the water, regardless of the water temperature, may cause a rapid drop in human body temperature. The specific heat capacity of water is relatively large, even if the patient does more intense activities, the body surface and muscle level is often very cool, once cooled, easy to cause muscle spasms. In addition, if the patient is swimming in the wild, the temperature may vary in different waters and different water layers. This is a good way to get the most out of your life. 2. It may be caused by excessive tension. Some first-time swimmers, or patients swimming in unknown waters, high tension may also lead to muscle spasms. 3, may be caused by excessive intense activity. Some patients do not warm up well before entering the water, and after entering the water, they quickly do very intense activities due to cold and other stimuli, which may cause muscle spasms.