Stavros A. Kavouras1, FACSM, J.D. Adams1, Matthew S. Ganio1, Michelle Gray1, Brendon P. McDermott1, Nicole Moyen1, Ashley Binns1, Evan C. Johnson2, Amy L. McKenzie2, Lawrence E. Armstrong2 FACSM. 1Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, AR.; 2Human Performance Laboratory, Department of Kinesiology, University of Connecticut, Storrs, CT.

Previous studies have suggested that both long-distance running and heat exposure are associated with high incidence of occult gastrointestinal (GI) bleeding. However, it is not clear wether prolonged non-impact exercise in the heat is associated with GI problems, which has been proposed as a predisposing factor for heat stroke. PURPOSE: The purpose of this research was to determine if competing in a 160-km cycling event in the heat has any effect on gastrointestinal bleeding. METHODS: Twenty-five experienced cyclists (21 men and 4 women; 49±9 y; 1.77±0.07 m; 83.7±14.8 kg) were recruited during a summer160-km cycling event (Hotter ‘n Hell Hundred). Immediately following the race, participants were given a fecal occult blood test and were instructed to retrieve their first bowel movement. One week following the race, participants were asked a series of questions regarding their GI discomforts. RESULTS: Environmental conditions for race day were 35.3±5.0 °C and 47.2±14.5% RH. Average finishing time for the participants was 6.58±1.22 h. Of the 25 cyclists participating in the study, two of them had positive results for fecal occult blood and GI distress, while two more experienced either constipation, hard stools, diarrhea or vomiting. CONCLUSION: These data showed a low incidence of gastrointestinal complaints and occult bleeding during a prolonged cycling event in the heat, indicating the low-impact exercise like cycling may attenuate some of the occult gastrointestinal bleeding previously reported in distance running in the heat.

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