GASTROINTESTINAL PERMEABILITY OF RUNNERS FOLLOWING THE 1996 CHICAGO MARATHON756:

Running at 80% VO2 max for 60 min was recently shown to significantly increase small intestinal permeability. The purpose of this study was to determine the effects of more prolonged exercise on gastroduodenal and intestinal permeability by measuring the urinary excretion of select carbohydrates during the first 5 h following the 1996 Chicago Marathon. Thirty-four healthy volunteers (20 male, 14 female; age = 40±2 yrs; weight = 67.7±1.8 kg) completed the race and ingested the test solution (5 g sucrose, 5 g lactulose, 2 g rhamnose, in 40 ml water) within 10-15 min. The ratio of lactulose/rhamnose (L/R) was used to assess small intestinal permeability whereas sucrose excretion was used to evaluate gastroduodenal permeability. Mean (±SE) training mileage(39.7±1.5 miles) postrace rectal temperature (38±0.2°C), and percent dehydration (-1.8±0.2) were unremarkable. The mean L/R for the group was 0.06±0.01; however, a subgroup of 6 subjects (18%) reporting aspirin or ibuprofen use before, during, or after the race had a mean L/R ratio of 0.12±0.02. This ratio equated with a value of 0.11±0.02 which represented a significant increase in small intestinal permeability following 60 min of treadmill exercise at 80% VO2 max. Five of the 6 subjects who ingested aspirin or ibuprofen reported GI symptoms. Sucrose secretion averaged 367±630 μmoles/5 h for the latter subjects compared with 169±57 μmoles/5 h for the entire group. Interestingly, 85% of all runners ingested alcohol and/or caffeine during or after the race, but this did not correlate with increased permeability. We conclude that ingestion of aspirin or ibuprofen during prolonged exercise can increase gastrointestinal permeability and lead to GI symptoms.