Changes in circulating immuno-inflammatory mediators following repeated exertional heat stress exposures in untrained males

Par Conseil national de recherches du Canada

DOI	Trouver le DOI : https://doi.org/10.1249/01.MSS.0000384644.52609.af
Auteur	Rechercher : Selkirk, Glen A.; Rechercher : Wright, Heather E.; Rechercher : Rhind, Shawn G.; Rechercher : McLellan, Tom. M.
Format	Texte, Allocution
Conférence	American College of Sports Medicine (ACSM) 57th Annual Meeting, June 2-5, 2010, Baltimore, MD
Résumé	Repeated exposure to hot environments is accompanied by a number of physiological adaptations, including improved thermoregulatory mechanisms which reduce physiological strain within the body and improve heat tolerance during subsequent exertional heat stress (EHS) exposures. To our knowledge, minimal data exists examining the relationship between circulating immuno-inflammatory mediators and the improvements in physiological heat tolerance accompanying repeated EHS exposures. PURPOSE: To examine the immune-inflammatory responses in untrained males following repeated EHS exposures and their relationship to classical physiological adaptations. METHODS: Nine sedentary males (Age = 27 ± 2 years, = 52 ± 2 mL·kgLBM-1·min-1, 17 ± 2% body fat) walked to exhaustion (Exh) at 4.5 km·h-1 with 2% elevation in a climatic chamber (40°C; 30% R.H.) while wearing encapsulating protective clothing for 9-days. Whole blood venous samples were collected at baseline (B) and Exh on Days 1 and 9 and analyzed by ELISA for circulating concentrations of IL-6, IL-1ra, nitric oxide (NO), soluble (s)CD14 and c-reactive protein (CRP). RESULTS: Repeated exertional heat stress exposure produced significant reductions in HR (142 ± 4 vs. 154 ± 4 b·min-1) and an increased time to Exh (145 ± 13 vs. 95± 8 min) on Day 9 compared to Day 1, respectively. No changes were observed in core temperature at B (36.7 ± 0.1 vs 36.6 ± 0.1 °C, p = 0.63), while a tendency for an increased core temperature tolerated at Exh (38.8 ± 0.1 vs 39.1 ± 0.1°C, p = 0.06) was observed between Days 1 and 9. Significantly elevated basal levels of sCD14, as well as tendencies for increased CRP (p = 0.06) and IL-1ra (p = 0.17), were observed on Day 9 compared to Day 1. During EHS, a significant increase in IL-6 (p = 0.01) and a tendency for enhanced NO production (p = 0.10) accompanied improved thermoregulation on Day 9. CONCLUSIONS: These findings suggest that classical thermoregulatory adaptations may be linked to immuno-inflammatory modulation following repeated EHS exposures, contributing to thermoregulatory adaptations and conferring enhanced cytoprotection for a given level of thermal strain.
Date de publication	2010-06-02
Maison d’édition	American College of Sports Medicine / Wolters Kluwer
Dans	Medicine and Science in Sports and Exercise 42, nº 5 Suppl. : 364–365.
Langue	anglais
Publications évaluées par des pairs	Oui
Publication du CNRC	Cette publication n’est pas du CNRC Ce sont des publications qui ont été rédigées par un auteur du CNRC, mais avant que celui-ci soit employé du CNRC.
Numéro NPARC	23001404
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Identificateur de l’enregistrement	2adecbb6-677e-4011-9f25-1febe43325f0
Enregistrement créé	2017-02-02
Enregistrement modifié	2020-03-03

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Date de modification :: 2023-06-02