The Importance of Aerobic Fitness in Extending Thermotolerance in Extreme Environments – Connecting Molecular Biology to the Whole Body Response

L’importance de la capacité aérobique pour l’augmentation de la thermotolérance dans des conditions extrêmes – Corrélations entre la biologie moléculaire et la réponse de l’organisme entier

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Authors
  1. McLellan, T.M.
  2. Selkirk, G.A.
  3. Wright, H.L.
  4. Rhind, S.G.
Corporate Authors
Defence R&D Canada - Toronto, Toronto ONT (CAN);York Univ, Toronto ONT (CAN)
Abstract
Introduction/Relevance Current theatres of military operations involve exposure to high ambient temperatures while wearing protective clothing such as fragmentation vests and/or the use of biological and chemical ensembles. Under conditions of uncompensable heat stress, aerobic fitness is a critical factor in explaining the higher core temperature (Tc) that can be tolerated by endurance trained (TR) versus untrained (UT) individuals. Tolerating higher Tc not only extends exposure time but it ensures that individuals can safely continue to be mobile while carrying their own weight and additional loads. Rationale The purpose of the current research was to examine whether differences in the immuno-inflammatory activation existed between TR and UT that might help explain the different Tc tolerated at exhaustion (EXH). Methods Twelve TR (24 + or - 1 y, 73.3 + or - 2.2 kg, 9.6 + or - 1.0 %fat, 62 + or - 2 ml/kg/min VO2peak) and eleven UT (23 + or - 1 y, 78.7 + or - 2.7 kg, 15.8 + or - 1.7 %fat, 42 + or - 1 ml/kg/min) walked at 4.5 km/h and a 2% grade to EXH in 40°C and 30% RH while wearing a biological and chemical protective overgarment. Blood was sampled at 0.5°C increments until Tc reached 40.0°C or the trial was terminated due to high heart rates, nausea, dizziness or volition. Plasma endotoxin and serum lipopolysaccharide binding protein (LBP) were determined as were intracellular pro- and anti-inflammatory cytokines and heat stress protein (HSP) in circulating monocytes us

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Keywords
gut barrier integrity, endotoxin leakage, intracellular cytokines, HSP72, apopto
Report Number
DRDC-TORONTO-SL-2009-105 — Scientific Literature
Date of publication
30 Oct 2009
Number of Pages
12
DSTKIM No
CA033355
CANDIS No
532701
Format(s):
Electronic Document(PDF)

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