Swimming hiccups may be caused by abdominal pressure, abdominal cold, breathing rate change and other factors. 1. Abdominal pressure: when swimming, the human body in the water abdomen will be subjected to water pressure, so that the organs are squeezed, the gas in the stomach in the role of external pressure, may be squeezed out, resulting in hiccups. 2. Abdominal cold: If the water temperature is low when swimming, resulting in abdominal cold, it will stimulate the diaphragm, making the diaphragm spasmodic contraction, resulting in hiccups. 3. Breathing frequency change: Swimming breathing needs to be at the surface of the water when the mouth is open to breathe, will make the gastrointestinal tract into the gas increase, but also will produce stimulation of the diaphragm, so that hiccups when swimming performance. You should prepare yourself well before swimming by not eating too much, especially gas-producing foods such as beans and sweet potatoes. If hiccups occur while swimming, you should adjust your breathing in time to avoid choking in the water.