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

journal contribution
posted on 2023-05-19, 14:09 authored by Snipe, RMJ, Khoo, A, Kitic, CM, Gibson, PR, Costa, RJS

Purpose: 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.

Methods: Ten endurance runners completed 2 h running at 60% V02max in hot (HOT: 35 °C) and temperate (TEMP: 22 °C)­ambient conditions. Rectal temperature (Tre) 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.

Results: Compared with TEMP, HOT significantly increased Tre (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 = 0.04 7, 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 Tre were posi­tively associated with I-FABP, IL-10, cortisol, nausea and urge to regurgitate (p < 0.05).

Conclusions: 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.

History

Publication title

European Journal of Applied Physiology

Volume

118

Pagination

389-400

ISSN

1439-6319

Department/School

School of Health Sciences

Publisher

Springer-Verlag

Place of publication

United States

Rights statement

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

Repository Status

  • Restricted

Socio-economic Objectives

Specific population health (excl. Indigenous health) not elsewhere classified

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