A 2003 study published in the American Medical Athletic Association evaluated stool from athletes after an intense workout or marathon and found fecal bleeding in 7 percent to 30 percent of samples. Study author Stephanie Horn explains that athletes who participate in intense physical activity, such as long-distance running, typically experience a condition known as "sports anemia." This is caused by diluted red blood cells. Other causes of rectal bleeding associated with exercise include hemorrhoids and anal fissures aggravated by running.
Digestive Disorders
Many marathoners, or those who rack up a lot of miles on the treadmill, have experienced rectal bleeding. Digestive disorders among athletes -- specifically runners -- are common, according to a 1990 report in the New Zealand journal Sports Medicine. Symptoms include rectal bleeding, diarrhea, loose stools, involuntary urination, nausea and vomiting. Symptoms tend to take place after hard workouts and can occur more frequently after athletic events with multiple components, such as triathlons. Some symptoms, such as diarrhea and stomach pain, have been linked to changes in the intestines. It's believed that cramps in the lower abdomen are caused directly by the impact exercise has on the colon.
Ischemic Colitis
Ischemic colitis, when the large intestine lacks oxygen rich blood cells, is a rare disorder associated with long-distance running. A 1997 study in the American Journal of Gastroenterology found that blood flow in the intestines, chronic dehydration and the propensity to develop blood clots linked to an abnormal number of red blood cells might be to blame. Common symptoms include bloody diarrhea and the urgent need to move your bowels. Most cases resolve on their own, but the condition can escalate and become severe. Your doctor may prescribe medication to regulate your blood pressure and antibiotics to prevent an infection. Some steps to take to prevent the disorder include controlling any chronic disease, such as diabetes, quitting smoking and taking medication to lower your cholesterol.
Hemorrhoids
Hemorrhoids result when blood vessels or veins around the anal area are dilated. Hemorrhoids can occur internally and externally. Those within the anus often don't cause pain but could protrude, bleed or discharge mucus. Athletes such as weightlifters are susceptible to hemorrhoids due to straining to lift heavy weights. They're also caused by straining from constipation. If you're constipated, try eating a diet high in fiber or taking a bulk-fiber laxative to soften your stool.
Prevention
Your doctor can perform a visual examination of your colon to rule out a lesion or inflammatory bowel disease, according to Dr. Cathy Fieseler, a Texas-based sports medicine practitioner. If your tests are negative, keep well-hydrated during workouts. Avoid using over-the-counter, anti-inflammatory medications such as aspirin and ibuprofen, which can cause gastrointestinal problems. MedlinePlus reports that ibuprofen, aspirin and other OTC drugs commonly cause bleeding in the upper gastrointestinal tract from stomach ulcers and inflammation.
References
- Highbeam Business: Gastrointestinal Bleeding in Endurance Runners
- PubMed.gov: The Effect of Exercise on the Gastrointestinal Tract
- MedlinePlus: Bloody or Tarry Stools
- MayoClinic.com: Ischemic Colitis
- American Journal of Gastroenterology: Wayne Lucas, MD; 1998
- Jackson Siegelbaum Gastroenterology: Rectal Bleeding
