title: The effects of increased endurance training load on biomarkers of heat intolerance during intense exercise in the heat.
abstract: The effects of increased training (IT) load on plasma concentrations of lipopolysaccharides (LPS), proinflammatory cytokines, and anti-LPS antibodies during exercise in the heat were investigated in 18 male runners, who performed 14 days of normal training (NT) or 14 days of 20% IT load in 2 equal groups. Before (trial 1) and after (trial 2) the training intervention, all subjects ran at 70% maximum oxygen uptake on a treadmill under hot (35 degrees C) and humid (~40%) conditions, until core temperature reached 39.5 degrees C or volitional exhaustion. Venous blood samples were drawn before, after, and 1.5 h after exercise. Plasma LPS concentration after exercise increased by 71% (trial 1, p < 0.05) and 21% (trial 2) in the NT group and by 92% (trial 1, p < 0.01) and 199% (trial 2, p < 0.01) in the IT group. Postintervention plasma LPS concentration was 35% lower before exercise (p < 0.05) and 47% lower during recovery (p < 0.01) in the IT than in the NT group. Anti-LPS IgM concentration during recovery was 35% lower in the IT than in the NT group (p < 0.05). Plasma interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha concentration after exercise (IL-6, 3-7 times, p < 0.01, and TNF-alpha, 33%, p < 0.01) and during recovery (IL-6, 2-4 times, p < 0.05, and TNF-alpha, 30%, p < 0.01) were higher than at rest within each group. These data suggest that a short-term tolerable increase in training load may protect against developing endotoxemia during exercise in the heat.
authors.affiliation: School of Human Movement Studies, University of Queensland, St Lucia, 4072, Brisbane, Australia. limcl@dso.org.sg
authors.forename: Chin Leong
authors.initials: CL
authors.lastname: Lim
authors.forename: David
authors.initials: D
authors.lastname: Pyne
authors.forename: Peggy
authors.initials: P
authors.lastname: Horn
authors.forename: Amelia
authors.initials: A
authors.lastname: Kalz
authors.forename: Philo
authors.initials: P
authors.lastname: Saunders
authors.forename: Jonathan
authors.initials: J
authors.lastname: Peake
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Suzuki
authors.forename: Gary
authors.initials: G
authors.lastname: Wilson
authors.forename: Laurel T
authors.initials: LT
authors.lastname: Mackinnon
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016207:Cytokines / Q000097:blood*; D019446:Endotoxemia / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D006339:Heart Rate; D018882:Heat Stress Disorders / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D006813:Humidity; D018836:Inflammation Mediators / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood; D008070:Lipopolysaccharides / Q000097:blood* / Q000276:immunology; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance; D013546:Sweating; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D000907:Antibodies, Bacterial; D015415:Biomarkers; D016207:Cytokines; C508600:IL6 protein, human; D018836:Inflammation Mediators; D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha