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The Impact of Mild Heat Stress during Prolonged Running on Gastrointestinal Integrity, Gastrointestinal Symptoms, Systemic Endotoxin and Cytokine Profiles

Version 2 2024-06-04, 14:30
Version 1 2018-06-18, 12:28
journal contribution
posted on 2024-06-04, 14:30 authored by Rhiannon SnipeRhiannon Snipe, A Khoo, CM Kitic, PR Gibson, RJS Costa
AbstractThe study aimed to determine the effects of mild exertional heat stress on intestinal injury, permeability, gastrointestinal symptoms, and systemic endotoxin and cytokine responses. Ten endurance runners completed 2 h of running at 60% V̇O2max in warm (WARM: 30°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) and cortisol concentrations, and systemic endotoxin and inflammatory cytokine profiles. Urinary lactulose:L-rhamnose ratio (L/R) was used to measure small intestine permeability. Compared with TEMP, WARM significantly increased Tre from 50 min onwards (38.1±0.3°C vs. 38.4±0.5°C, respectively; p<0.01), gastrointestinal symptoms (p=0.017), post-exercise plasma cortisol (26% vs. 59%, respectively; p<0.001) and I-FABP (127% vs. 184%, respectively; p<0.001) concentrations. Circulatory anti-endotoxin antibodies increased post-exercise (p<0.001) on WARM (20%) and TEMP (28%). No differences were observed for plasma endotoxin concentration (6% vs. 5% increase, respectively) or small intestine permeability (L/R 0.026±0.010 and 0.025±0.015, respectively). Both pro- and anti-inflammatory cytokines increased post-exercise, with inflammatory response cytokines TNF-α (p=0.015) and IL-8 (p=0.044), and compensatory anti-inflammatory cytokines IL-10 (p=0.065), and IL-1ra higher on WARM than TEMP. Findings suggest that exposure to warm ambient conditions during prolonged submaximal running induces transient intestinal epithelial injury, increases gastrointestinal symptoms, and promotes greater perturbations to the systemic cytokine profile compared to running in temperate conditions.

History

Journal

International Journal of Sports Medicine

Volume

39

Pagination

255-263

Location

Germany

ISSN

0172-4622

eISSN

1439-3964

Language

English

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2018, Georg Thieme Verlag KG Stuttgart

Issue

4

Publisher

GEORG THIEME VERLAG KG