Acute high-intensity interval running increases markers of gastrointestinal damage and permeability but not gastrointestinal symptoms

Purpose To investigate the effects of high-intensity interval (HIIT) running on markers of gastrointestinal (GI) damage and permeability alongside subjective symptoms of GI discomfort. Methods Eleven male runners completed an acute bout of HIIT (eighteen 400 m runs at 120% VO2max ) where markers of GI permeability, intestinal damage and GI discomfort symptoms were assessed and compared with resting conditions. Results Compared to rest, HIIT significantly increased serum lactulose:rhamnose ratio (0.051 ± 0.016 vs. 0.031 ± 0.021, p = 0.0047; 95% CI = 0.006 - 0.036) and sucrose concentrations (0.388 ± 0.217 vs 0.137 ± 0.148 mg.l-1; pThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author