Gastrointestinal bleeding following a 161-km cycling race in the heat: A pilot study

J. D. Adams, Stavros A. Kavouras, Evan C. Johnson, Matthew S. Ganio, Michelle Gray, Brendon P. McDermott, Amy L. McKenzie, Elaine C. Lee, Lawrence E. Armstrong

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Background: Occult (i.e., non-visible) gastrointestinal (GI) bleeding is a well-recognized complication that can occur during vigorous endurance physical exertion, especially in the heat. Objectives: The purpose of this study was to investigate the incidence of GI bleeding during a non-impact (cycling) prolonged race (161-km) in the heat. Methods: Twenty-five experienced cyclists (21 males and 4 females, 49 ± 9 y, 83.7 ± 14.8 kg) were completed a summer 161-km cycling event. Following the race, participants were given a fecal occult blood test and were instructed to retrieve their first bowel movement. Results: Mean race dry air and wet bulb globe temperature (WBGT) were 36.0 ± 5.2°C, and 31.8 ± 3.6°C, respectively. Of the 25 subjects, two (8%) produced positive results for fecal occult blood while an additional two (16%) experienced constipation, hard stools, diarrhea or vomiting. Conclusions: These data showed a low incidence of GI complaints and occult bleeding during a prolonged cycling event in the heat, indicating the low-impact exercise such as cycling may lessen some of the occult GI bleeding previously reported in distance running in the heat.

Original languageEnglish (US)
Article numbere60900
JournalAsian Journal of Sports Medicine
Issue number1
StatePublished - Mar 2018
Externally publishedYes


  • Anemia
  • Body temperature regulation
  • Endurance exercise
  • Occult blood
  • Thermoregulation

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine


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