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

Abstract

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, in-vitro 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 d, two-tailed correlation, and intraclass correlation coefficient (ICC) of resting biomarkers presented good-to-excellent for IL-1ra (r = 0.710, ICC = 0.92), IL-10 (r = 0.665, ICC = 0.73), cortisol (r = 0.870, ICC = 0.87), and LBP (r = 0.813, ICC = 0.76); moderate for total (r = 0.839, ICC = 0.44) and per cell (r = 0.749, ICC = 0.54) bacterially-stimulated elastase release, IL-1β (r = 0.625, ICC = 0.64), TNF-α (r = 0.523, ICC = 0.56), I-FABP (r = 0.411, ICC = 0.21), and sCD14 (r = 0.409, ICC = 0.38), plus fecal bacterial α-diversity; and poor for leukocyte (r = 0.327, ICC = 0.33) and neutrophil (r = 0.352, ICC = 0.32) counts. In addition, a medium negative correlation was observed between plasma butyrate and I-FABP (r = −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.

Exertional Stress-induced Pathogenic Luminal Content Translocation – Friend or Foe?

“…This is supported by recent findings in exercise gastroenterology research that demonstrates that the most prominent bacterial phyla present pre-to post-exercise are Proteobacteria, Firmicutes, Actinobacteroita, then and Bacteroidota [20][21][22]. These findings were established by using standard methodologies of bacterial analysis, which involves quantification of microbial DNA concentration via PCR amplification and Qubit Fluorometry, followed by full plasma bacterial profiling via 16 S Gene Sequencing [20][21][22]. By utilizing this method, the utmost accuracy and depth of exploration of the translocation of all bacterial species from the gastrointestinal lumen into systemic circulation can be achieved.…”

“…By limiting microbial DNA investigations to Bacteroidota alone, there is no true assessment of microbial DNA concentration and/or no full bacterial profile determined. This is supported by recent findings in exercise gastroenterology research that demonstrates that the most prominent bacterial phyla present pre- to post-exercise are Proteobacteria, Firmicutes, Actinobacteroita, then and Bacteroidota 20 21 22 . These findings were established by using standard methodologies of bacterial analysis, which involves quantification of microbial DNA concentration via PCR amplification and Qubit Fluorometry, followed by full plasma bacterial profiling via 16 S Gene Sequencing 20 21 22 .…”

“…Eleven studies investigated bacterial endotoxin infiltration change (Δ) pre-to post-exercise specifically via LPS [54][55][56][57][58][59][60][61][62][63][64]. While eight studies analyzed translocation via non-descript bacterial endotoxin, and five studies analyzed LBP translocation [4,20,[65][66][67][68][69][70][71][72][73][74][75]. It must be recognized that assessing endotoxemia via LBP translocation may result in misleading and/or misinterpreted outcomes, as exercise stress magnitude can influence LBP utilization and direction of concentration change pre-to post-exercise [10].…”

Does Age Influence Gastrointestinal Status Responses to Exertional-heat Stress?

“…Participants were provided with an individualized diet low in fermentable oligo-, di-, mono-saccharide and polyols (FODMAP) for the 24-h period before each experimental trial [mean(SD): 11.0 (2.7) MJ/day, 416 (118) g/day carbohydrate (64 %), 101 (22) g/day protein (15 %), 60 (16) g/day fat (21 %), 46 (16) g/day fiber, and < 5 g/day FODMAP] to limit any confounding factors associated with the lead in diet [14]. Participants were asked to refrain from consuming additional high FODMAP foods, alcohol, and caffeinated beverages during the diet-controlled period, and avoid strenuous exercise during the 48-h period before each experimental trial.…”

“…Within the EIGS pathogenic model, both extrinsic and intrinsic exacerbation factors have been described to influence the incidence and severity of EIGS and associated Ex-GIS in response to exercise [1,2,14]. Notably, it has consistently been reported that substantial rises in core body temperature in response to EHS profoundly exacerbates intestinal epithelial disturbances to levels of clinical significance, in comparison to exertional stress or EHS models with more modest rises in core body temperature [5,6,[15][16][17]. This provides support for heat exposure during exercise as a primary and potent extrinsic factor in the exacerbation of EIGS and Ex-GIS over other documented extrinsic exacerbation factors (e. g. exercise duration, intensity, modality) [1,2,14].…”