European Journal of Applied Physiology

, Volume 118, Issue 2, pp 389–400 | Cite as

The impact of exertional-heat stress on gastrointestinal integrity, gastrointestinal symptoms, systemic endotoxin and cytokine profile

  • Rhiannon M. J. Snipe
  • Anthony Khoo
  • Cecilia M. Kitic
  • Peter R. Gibson
  • Ricardo J. S. CostaEmail author
Original Article



The study aimed to determine the effects of exertional-heat stress on gastrointestinal integrity, symptoms, systemic endotoxin and inflammatory responses; and assess the relationship between changes in body temperature and gastrointestinal perturbations.


Ten endurance runners completed 2 h running at 60% \(\dot {V}\)O2max in hot (HOT: 35 °C) and temperate (TEMP: 22 °C)-ambient conditions. Rectal temperature (T re) and gastrointestinal symptoms were recorded every 10 min during exercise. Blood samples were collected pre- and post-exercise, and during recovery to determine plasma intestinal fatty acid binding protein (I-FABP), cortisol, bacterial endotoxin and cytokine profile. Calprotectin was determined from pre- and post-exercise faecal samples. Urinary lactulose:l-rhamnose ratio was used to measure intestinal permeability.


Compared with TEMP, HOT significantly increased T re (1.4 ± 0.5 vs 2.4 ± 0.8 °C, p < 0.001), cortisol (26 vs 82%, p < 0.001), I-FABP (127 vs 432%, p < 0.001), incidence (70 vs 90%) and severity (58 counts vs 720 counts, p = 0.008) of total gastrointestinal symptoms. Faecal calprotectin and circulating endotoxin increased post-exercise in both trials (mean increase 1.5 ± 2.5 µg/g, p = 0.032, and 6.9 ± 10.3 pg/ml, p = 0.047, respectively), while anti-endotoxin antibodies increased 28% post-exercise in TEMP and decreased 21% in HOT (p = 0.027). However, intestinal permeability did not differ between trials (p = 0.185). Inflammatory cytokines were greater on HOT compared to TEMP (p < 0.05). Increases in T re were positively associated with I-FABP, IL-10, cortisol, nausea and urge to regurgitate (p < 0.05).


Exertional-heat stress induces a thermoregulatory strain that subsequently injures the intestinal epithelium, reduces endotoxin clearance capacity, promotes greater cytokinaemia, and development of gastrointestinal symptoms.


Euhydration Running Permeability I-FABP Calprotectin Inflammation 



Analysis of variance


Confidence interval


Coefficient of variation


Enzyme-linked immunosorbent assay


Fermentable oligosaccharides, disaccharides, monosaccharides and polyols


Hot conditions (35 °C ambient temperature).


Interleukin 1 beta


Interleukin 1 receptor antagonist


Interleukin 6


Interleukin 8


Interleukin 10


Intestinal fatty acid binding protein


Rating of perceived exertion


Standard deviation


Standard error of the mean


Temperate conditions (22 °C ambient temperature).


Tumor necrosis factor alpha


Rectal temperature

\(\dot {V}\)O2max

Maximal oxygen uptake


Maximum workload



First, the authors would like to thank all the participants that volunteered to take part in this study. The authors’ contributions are as follows: Ricardo Costa (RC) was the chief investigator of this research. RC, Rhiannon Snipe (RS), and Peter Gibson (PG) contributed towards the original research idea and development of the experimental design. RC, RS, Anthony Khoo (AK), and Cecilia Kitic (CK) contributed to the various aspects of data collection, and sample collection and analysis. RC and RS contributed to the analysis of the raw data. All authors contributed to the preparation and review of the manuscript. All authors read and approved the final manuscript. The study was supported by the ‘Monash University, Faculty of Medicine Nursing and Health Sciences Strategic Grant Scheme’.

Compliance with ethical standards

Conflict of interest

PG has served as consultant or advisory board member for AbbVie, Ferring, Janssen, Merck, Nestle Health Science, Danone, Allergan, Pfizer, Celtrion and Takeda. His institution has received speaking honoraria from AbbVie, Janssen, Ferring, Takeda, Fresenius Kabi, Mylan and Pfizer. He has received research Grants for investigator-driven studies from AbbVie, Janssen, Falk Pharma, Danone and A2 Milk Company. His Department financially benefits from the sales of a digital application and booklets on the low FODMAP diet. Other authors have nothing to declare.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  1. 1.Department of Nutrition Dietetics and FoodMonash UniversityNotting HillAustralia
  2. 2.Sport Performance Optimisation Research Team, School of Health SciencesUniversity of TasmaniaLauncestonAustralia
  3. 3.Department of Gastroenterology, The Alfred HospitalMonash UniversityMelbourneAustralia

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