Runner's diarrhea

Runner's diarrhea causes frequent, loose bowel movements during or immediately after a run. This usually is a problem in long-distance or marathon runners. The cause of runner's diarrhea isn't clear. One theory is that the up and down movement of the body during running may stimulate bowel activity. Another theory is that running increases the speed at which food passes through your digestive tract.

Dietary changes that may reduce or prevent runner's diarrhea include:

• Avoid eating for at least two hours before running.
• Drink plenty of fluids before and after exercise. Dehydration can lead to diarrhea. However, avoid warm liquids, which can speed food through the digestive tract.
• Avoid high-fat foods before running, which can contribute to diarrhea.
• Reduce fiber and gas-producing foods for at least one day before running. These include beans, bran, fruits and salad. If you run every day, you'll have to find a level of fiber that you can tolerate. Otherwise, you can eat high-fiber and gas-producing foods after you run.
• Limit or avoid caffeine, which stimulates the bowel, for three to six hours before running.
• Limit or avoid sweeteners called sugar alcohols, which stimulate the bowel, for at least one day before running. Sugar alcohols are most often found in sugar-free candies, gum and ice cream.
• If you're lactose intolerant, switch to lactose-reduced or lactose-free milk and milk products.

When you run, be sure to wear comfortable, loose-fitting clothing. Clothing that is too tight around the waist may increase diarrhea.

In addition, if you have runner's diarrhea, you may consider reducing the intensity or distance of your runs until the diarrhea improves. Then gradually increase your activity as signs and symptoms allow. If these suggestions don't help, consult your doctor.