The effects of increased endurance training load on biomarkers of heat intolerance during intense exercise in the heat

• Published in: Applied physiology, nutrition, and metabolism Vol. 34; no. 4; pp. 616 - 624
• Main Authors: Lim, Chin Leong, Pyne, David, Horn, Peggy, Kalz, Amelia, Saunders, Philo, Peake, Jonathan, Suzuki, Katsuhiko, Wilson, Gary, Mackinnon, Laurel T
• Format: Journal Article
• Language: English
• Published: Ottawa Presses scientifiques du CNRC 01.08.2009; NRC Research Press; Canadian Science Publishing NRC Research Press
• Subjects: anti-LPS antibodies; Antibodies, Bacterial - blood; anticorps anti-LPS; Athletes; Biological and medical sciences; Biological markers; Biomarkers; Biomarkers - blood; Body temperature; Causes of; Cytokines; Cytokines - blood; endotoxemia; Endotoxemia - blood; Endotoxemia - etiology; Endotoxemia - prevention & control; endotoxémie; Exercise; Fundamental and applied biological sciences. Psychology; Health aspects; Heart Rate; Heat; Heat stress disorders; Heat Stress Disorders - blood; Heat Stress Disorders - etiology; Heat Stress Disorders - prevention & control; heat tolerance; Hot Temperature - adverse effects; Humans; Humidity; Inflammation Mediators - blood; Interleukin-6 - blood; lipopolysaccharides; Lipopolysaccharides - blood; Lipopolysaccharides - immunology; Male; Oxygen Consumption; Physical Endurance; Physiological aspects; Prevention; Sweating; Time Factors; tolérance à la chaleur; Tumor Necrosis Factor-alpha - blood; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports; Australia; Canada; Physical exercise; Human; Temperature; Heat; Physical training; Cytokine; Biological marker; Tolerance; Environmental factor; Endurance; Endotoxemia
• ISSN: 1715-5312; 1715-5320
• DOI: 10.1139/H09-021

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 °C) and humid (∼40%) conditions, until core temperature reached 39.5 °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)- α concentrations after exercise (IL-6, 3−7 times, p < 0.01, and TNF- α, 33%, p < 0.01) and during recovery (IL-6, 2−4 times, p < 0.05, and TNF- α, 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.