I am a 46-year-old male who's been running for 15 years. Recently, while in training for a marathon, I awoke with severe lower abdominal cramps and bloody stool. A colonoscopy revealed bleeding and heavy liquid stool in the transverse and ascending colon. No diverticula were seen, and tests were negative for bacterial or parasitic infection. My GI doctor suspects the problem may be ischemic colitis related to my running routine, and he wants me to stop running for a month. He says that during running, blood flow to the GI tract can be reduced by 60-70 percent. Have you ever heard of running causing ischemic colitis? If so, what precautions can I take -- short of stopping running -- to avoid another attack?

Robert

Ischemic colitis is a condition in which a reduced blood flow to the colon results in inflammation with ulcerations and bleeding. Viewed directly through an endoscope (a medical device inserted through the throat and into the digestive tract) it may appear similar to other types of colitis (such as ulcerative colitis), Crohn's disease, or a bacterial or parasitic infection.

Several factors can reduce blood flow to the colon, resulting in ischemic colitis. These include blood clots, atherosclerosis in the abdominal blood vessels (similar to blockages found in the heart), poor blood flow to the colon (as seen in patients with heart failure or low blood pressure) and even certain medications (digoxin, for example).

Long-distance running has been implicated as a cause of ischemic colitis in several reports in the medical literature. As your doctor mentioned, the mechanism involved apparently relates to reduced blood flow to the colon during running. It also probably involves dehydration (as a result of running), which makes the blood thicker and more likely to clot in small vessels.

I agree with your doctor that you should stop running for some time. However, although ischemic colitis can occur as a result of running, it is not common. So, it is very important for you to be evaluated to rule out other blood-vessel problems that may have contributed to the colitis. A referral to a cardiologist may help in this case.