The increase in core body temperature in response to exertional-heat stress can predict exercise-induced gastrointestinal syndrome

ABSTRACT

Utilizing metadata from existing exertional and exertional-heat stress studies, the study aimed to determine if the exercise-associated increase in core body temperature can predict the change in exercise-induced gastrointestinal syndrome (EIGS) biomarkers and exercise-associated gastrointestinal symptoms (Ex-GIS). Endurance-trained individuals completed 2 h of running exercise in temperate (21.2-30.0°C) to hot (35.0-37.2°C) ambient conditions (n = 132 trials). Blood samples were collected pre- and post-exercise to determine the change in gastrointestinal integrity biomarkers and systemic inflammatory cytokines. Physiological and thermoregulatory strain variables were assessed every 10–15 min during exercise. The strength of the linear relationship between maximal (M-Tre) and change (Δ Tre) in rectal temperature and EIGS variables was determined via Spearman’s rank correlation coefficients. While the strength of prediction was determined via simple and multiple linear regression analyses dependent on screened EIGS and Ex-GIS confounding factors. Significant positive correlations between Tre maximum (M-Tre) and change (Δ Tre) with I-FABP (rs = 0.434, p < 0.001; and rs = 0.305, p < 0.001; respectively), sCD14 (rs = 0.358, p < 0.001; and rs = 0.362, p < 0.001), systemic inflammatory response profile (SIR-Profile) (p < 0.001), and total Ex-GIS (p < 0.05) were observed. M-Tre and Δ Tre significantly predicted (adjusted R2) magnitude of change in I-FABP (R2(2,123)=0.164, p < 0.001; and R2(2,119)=0.058, p = 0.011; respectively), sCD14 (R2(2,81)=0.249, p < 0.001; and R2(2,77)=0.214, p < 0.001), SIR-Profile (p < 0.001), and total Ex-GIS (p < 0.05). Strong to weak correlations were observed between M-Tre and Δ Tre with plasma concentrations of I-FABP, sCD14, SIR-Profile, and Ex-GIS in response to exercise. M-Tre and Δ Tre can predict the magnitude of these EIGS variables and Ex-GIS in response to exercise.

KEYWORDS:

• Exertional
• heat
• I-FABP
• endotoxin
• inflammatory cytokines
• gastrointestinal symptoms
• thermoregulation
• endurance

Acknowledgments

The authors would like to show our appreciation to all participants that volunteered within the study and would also like to thank the Monash University Sports Dietetics & Extremes Physiology Group and collaborators for their data/sample collection and/or analysis contributions. The research study procedures were performed at the BASE Facility, Department of Nutrition, Dietetics & Food, Faculty of Medicine, Nursing & Health Sciences, Monash University, Melbourne, Australia. The author’s contributions are as follows: RC was the Chief Investigator of the included research studies. All authors continued in some form to the collection and analysis of samples of the included studies. KH and RC contributed to the data analysis and prepared the initial draft manuscript. All authors contributed to the review, adjustment and final draft of the manuscript. All authors approved the final manuscript prior to submission.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/23328940.2023.2213625.

Additional information

Funding

The work was supported by the Faculty of Medicine, Nursing and Health Sciences, Monash University [Strategic Grant Scheme]; Entrinsic Biosciences [Research Service Agreement]; Lion Drinks and Dairy [GRIP Food and Dairy]; Sports Medicine Australia Research Foundation [Postgraduate research fund]