title: Circulatory endotoxin concentration and cytokine profile in response to exertional-heat stress during a multi-stage ultra-marathon competition.
abstract: Exertional-heat stress has the potential to disturb intestinal integrity, leading to enhanced permeability of enteric pathogenic micro-organisms and associated clinical manifestations. The study aimed to determine the circulatory endotoxin concentration and cytokine profile of ultra-endurance runners (UER, n=19) and a control group (CON, n=12) during a five stage 230km ultra-marathon (mean ± SD: 27h38min ± 3h55min) conducted in hot and dry environmental conditions (30ºC to 40ºC and 31% to 40% relative humidity). Body mass and tympanic temperature were measured, and venous blood samples were taken before (pre-stage) and immediately after (post-stage) each stage of the ultra-marathon for the analysis of gram-negative bacterial endotoxin, C-reactive protein, cytokine profile (IL-6, IL-1β, TNF-α, IFN-γ, IL-10, and IL- 1ra), and plasma osmolality. Gastrointestinal symptoms and perceptive thermal tolerance rating were also monitored throughout competition. Mean exercise-induced body mass loss over the five stages ranged 1.0% to 2.5%. Pre- and poststage plasma osmolality in UER ranged277 to 282mOsmol/kg and 286 to 297 mOsmol/kg, respectively. Pre-stage concentrations of endotoxin (peak: 21% at Stage 5), C-reactive protein (889% at Stage 3), IL-6 (152% at Stage 2), IL-1β (95% at Stage 5), TNF-α (168% at Stage 5), IFN-γ (102% at Stage 5),IL-10 (1271% at Stage 3), and IL-1ra (106% at Stage 5) increased as the ultra-marathon progressed in UER; while no changes in CON were observed (except for IL-1β, 71% at Stage 5). Pre- to post-stage increases were observed for endotoxin (peak: 22% at Stage 3), C-reactive protein (25% at Stage 1), IL-6 (238% at Stage 1), IL-1β (64% at Stage 1), TNF-α (101% at Stage 1), IFN-γ (39% at Stage 1), IL-10 (1100% at Stage 1), and IL-1ra(207% at Stage 1) concentrations in UER. Multi-stage ultra-marathon competition in the heat resulted in a modest circulatory endotoxaemia accompanied by a pronounced pro-inflammatory cytokinaemia by post-Stage 1, both of which were sustained throughout competition at rest (pre-stage) and after stage completion. Compensatory anti-inflammatory responses and other external factors (i.e., training status, cooling strategies, heat acclimatization, nutrition and hydration) may have contributed towards limiting the extent of pro-inflammatory responses in the current scenario.
authors.affiliation: Sport & Exercise Science Applied Research Group, Coventry University, Priory Street, Coventry, CV1 5FB, United Kingdom.
authors.forename: Samantha K
authors.initials: SK
authors.lastname: Gill
authors.affiliation: Faculty of Sport Science & Physical Education, Pavilion 3, Santa Clara, 3040-156, Coimbra University, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Teixeira
authors.affiliation: Faculty of Sport Science & Physical Education, Pavilion 3, Santa Clara, 3040-156, Coimbra University, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Rama
authors.affiliation: Programa de Pós-Graduação em Educação Física, Universidade Católica de Brasília, DF, Brasil.
authors.forename: Jonato
authors.initials: J
authors.lastname: Prestes
authors.affiliation: Programa de Pós-Graduação em Educação Física, Universidade Católica de Brasília, DF, Brasil.
authors.forename: Fatima
authors.initials: F
authors.lastname: Rosado
authors.affiliation: Sport & Exercise Science Applied Research Group, Coventry University, Priory Street, Coventry, CV1 5FB, United Kingdom.
authors.forename: Joanne
authors.initials: J
authors.lastname: Hankey
authors.affiliation: British Forces Germany Health Services, Paderborn, BFPO 16, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Scheer
authors.affiliation: Sport & Exercise Science Applied Research Group, Coventry University, Priory Street, Coventry, CV1 5FB, United Kingdom.
authors.forename: Krystal
authors.initials: K
authors.lastname: Hemmings
authors.affiliation: Faculty of Health & Life Sciences, Northumberland University, Ellison Place, Newcastle upon Tyne, NE1 8ST, United Kingdom.|Department of Physiological Sciences, Stellenbosch University, Matieland, 7602, South Africa.
authors.forename: Paula
authors.initials: P
authors.lastname: Ansley-Robson
authors.affiliation: Sport & Exercise Science Applied Research Group, Coventry University, Priory Street, Coventry, CV1 5FB, United Kingdom.|Department of Nutrition and Dietetics, Monash University, Level 1, 264 Ferntree Gully Road, Notting Hill, Victoria 3168, Australia.
authors.forename: Ricardo J S
authors.initials: RJ
authors.lastname: Costa
mesh_terms: D000328:Adult; D056352:Athletes; D018988:Bacterial Translocation; D002097:C-Reactive Protein / Q000032:analysis; D016207:Cytokines / Q000097:blood*; D004326:Drinking; D004573:Electrolytes / Q000008:administration & dosage; D019446:Endotoxemia / Q000097:blood / Q000209:etiology*; D002149:Energy Intake; D005260:Female; D006090:Gram-Negative Bacteria / Q000737:chemistry; D006359:Heat Exhaustion / Q000097:blood / Q000209:etiology; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000209:etiology* / Q000517:prevention & control; D008070:Lipopolysaccharides / Q000097:blood*; D008297:Male; D009994:Osmolar Concentration; D005082:Physical Exertion / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013312:Stress, Physiological / Q000276:immunology / Q000502:physiology*; D015431:Weight Loss
chemical_list: D016207:Cytokines; D004573:Electrolytes; D008070:Lipopolysaccharides; D002097:C-Reactive Protein
keywords: endurance; gastrointestinal.; heat; inflammation; running