Some people experience stomach cramps or intestinal pain after a vigorous workout. Athletes who run or compete in high-intensity competitions such as biathlons or Iron Man competitions also sometimes report abdominal pain after strenuous training or performances. Although the severity and duration of the discomfort vary with the individual, some common causes have been linked to stomach pain after strenuous exercise.
According to Mary A. Jenkins, M.D., and Caryn Honig, R.D., at Rice University, hydration depends on the rate at which fluids are emptied from the stomach. Stomach pain can occur after the activity if there is insufficient fluid in the body before and during exercise, or if the amount of fluid lost by sweating exceeds the intake. Cool liquids leave the stomach faster than body-temperature ones, and drinks with a high simple-sugar content, such as soft drinks, leave more slowly than water or sports drinks. Athletes are advised to over-hydrate with water or sports drinks before strenuous exercise, but not enough to feel too full. In addition, they should consume cool liquids every 10 to 15 minutes during exercise and avoid sugary drinks to keep up with fluid loss through sweating.
The Rice University personnel also contend that the type of food consumed prior to strenuous exercise can also cause stomach pain. Foods high in fibre, carbohydrates, fat, and protein can cause cramps and other gastrointestinal problems. Some runners avoid these effects by using a carbohydrate supplement instead of eating rice or pasta, to minimize material in the upper digestive tract during exercise.
Stomach Acid Increase
Dr. Zhou Xianbin, who leads the Department of Gastroenterology at China’s Taizhou Hospital, reports that heavy exercise causes the stomach to produce excess acid. He maintains that consuming spicy food just after a rigorous workout can irritate the stomach and cause pain.
Dr. Gabe Mirkin contends that, when the stomach is full, stomach muscles require a great deal of blood in order to promote the digestion process. If the heart is not strong enough to pump blood to the stomach muscles and also to other muscles during strenuous exercise, lactic acid builds up in the stomach muscles, causing pain. People can avoid these problems by not eating within 30 minutes prior to exercise. However, an athlete must be sure to consume a sufficient amount of calories for the body to be able to stand up to the rigors of the exercise.
Hypertonic sports drinks -- those with higher than 8 percent concentrations of minerals and carbohydrates -- may cause stomach pain after intense exercise. The principle is the same as overloading the stomach with food high in carbohydrates, notes the website Cycling Performance Tips.