AUTHOR=Young Pascale , Russo Isabella , Gill Paul , Muir Jane , Henry Rebekah , Davidson Zoe , Costa Ricardo J. S. 

TITLE=Reliability of pathophysiological markers reflective of exercise-induced gastrointestinal syndrome (EIGS) in response to 2-h high-intensity interval exercise: A comprehensive methodological efficacy exploration

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1063335

DOI=10.3389/fphys.2023.1063335

ISSN=1664-042X

ABSTRACT=<p>The study aimed to determine the test-retest reliability of exercise-induced gastrointestinal syndrome (EIGS) biomarkers, and assess the association of pre-exercise short chain fatty acid (SCFA) concentration with these biomarkers in response to prolonged strenuous exercise. Thirty-four participants completed 2 h of high-intensity interval training (HIIT) on two separate occasions with at least 5-days washout. Blood samples were collected pre- and post-exercise, and analysed for biomarkers associated with EIGS [i.e., cortisol, intestinal fatty-acid binding protein (I-FABP), sCD14, lipopolysaccharide binding protein (LBP), leukocyte counts, <italic>in-vitro</italic> neutrophil function, and systemic inflammatory cytokine profile]. Fecal samples were collected pre-exercise on both occasions. In plasma and fecal samples, bacterial DNA concentration was determined by fluorometer quantification, microbial taxonomy by 16S rRNA amplicon sequencing, and SCFA concentration by gas-chromatography. In response to exercise, 2 h of HIIT modestly perturbed biomarkers indicative of EIGS, including inducing bacteremia (i.e., quantity and diversity). Reliability analysis using comparative tests, Cohen’s <italic>d</italic>, two-tailed correlation, and intraclass correlation coefficient (ICC) of resting biomarkers presented good-to-excellent for IL-1ra (<italic>r</italic> = 0.710, ICC = 0.92), IL-10 (<italic>r</italic> = 0.665, ICC = 0.73), cortisol (<italic>r</italic> = 0.870, ICC = 0.87), and LBP (<italic>r</italic> = 0.813, ICC = 0.76); moderate for total (<italic>r</italic> = 0.839, ICC = 0.44) and per cell (<italic>r</italic> = 0.749, ICC = 0.54) bacterially-stimulated elastase release, IL-1β (<italic>r</italic> = 0.625, ICC = 0.64), TNF-α (<italic>r</italic> = 0.523, ICC = 0.56), I-FABP (<italic>r</italic> = 0.411, ICC = 0.21), and sCD14 (<italic>r</italic> = 0.409, ICC = 0.38), plus fecal bacterial α-diversity; and poor for leukocyte (<italic>r</italic> = 0.327, ICC = 0.33) and neutrophil (<italic>r</italic> = 0.352, ICC = 0.32) counts. In addition, a medium negative correlation was observed between plasma butyrate and I-FABP (<italic>r</italic> = −0.390). The current data suggest a suite of biomarkers should be used to determine the incidence and severity of EIGS. Moreover, determination of plasma and/or fecal SCFA may provide some insight into the mechanistic aspects of EIGS instigation and magnitude in response to exercise.</p>