Gastrointestinal bleeding during an ultramarathon.

A prospective study was undertaken to determine the frequency of detectable gastrointestinal bleeding in participants of a 100-mile running race. Pre- and postrace questionnaires were utilized to determine training data, gastrointestinal symptoms, diet, and the use of medications during training and during the race, prior known gastrointestinal disease, and 100-mile race experience. Three prerace and the first three postrace stools were sampled for blood using the standard Hemoccult method in 35 runners: 85% of the participants who were Hemoccult negative before the race converted to positive in their postrace samples. Runners with the postrace Hemoccult-positive stools had more frequent and intense nausea, diarrhea, abdominal cramping, and bloating (P less than 0.05) during the race. Lower gastrointestinal symptoms correlated with Hemoccult positivity (P less than 0.05), whereas upper gastrointestinal symptoms did not. The majority of participants showed evidence of gastrointestinal bleeding after the race. Digestive symptoms are common and lower gastrointestinal symptoms correlate with gastrointestinal bleeding.