title: Blood-brain barrier integrity may be threatened by exercise in a warm environment.
abstract: Seven active men were recruited to examine changes in the serum concentration of S100beta, a proposed peripheral marker of blood-brain barrier permeability, following prolonged exercise in temperate (T) and warm (W) conditions. Subjects were seated immersed to the neck in water at 35.0 (0.1) degrees C (T) or 39.0 (0.1) degrees C (W) for 30 min. Subjects then entered a room maintained at either 18.3 (1.8) degrees C (T) or 35.0 (0.3) degrees C (W) and completed 60 min of cycle exercise at 60% peak oxygen uptake. Serum S100beta concentration was elevated after exercise in the W trial (+0.12 (0.10) microg/l; P = 0.02) but not after the T trial (P = 0.238). Water immersion and exercise elevated core temperature by 2.1 (0.5) degrees C to 39.5 (0.3) degrees C at the end of exercise in the W trial compared with a 0.9 (0.2) degrees C increase during the T trial (P < 0.001). Weighted mean skin temperature was higher throughout the W trial compared with the T trial (P < 0.001). Heart rate (P < 0.001) and blood glucose (P < 0.001) and lactate (P < 0.001) concentrations were elevated to a greater extent during exercise in the W trial than in the T trial. Ratings of perceived exertion (P < 0.001) and thermal comfort (P < 0.001) were markedly higher throughout the W trial than in the T trial. The results of this study demonstrate that serum S100beta was elevated after water immersion and prolonged exercise in a warm environment, suggesting that blood-brain barrier permeability may be altered.
authors.affiliation: School of Sport and Exercise Sciences, Loughborough University, Leicestershire LE11 3TU, UK.
authors.forename: Phillip
authors.initials: P
authors.lastname: Watson
authors.forename: Susan M
authors.initials: SM
authors.lastname: Shirreffs
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Maughan
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001642:Bicycling; D015415:Biomarkers; D001786:Blood Glucose / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000502:physiology*; D001831:Body Temperature; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000503:physiopathology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D007101:Immersion; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009414:Nerve Growth Factors; D010101:Oxygen Consumption / Q000187:drug effects; D010953:Plasma Volume / Q000502:physiology; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000378:metabolism; D013696:Temperature
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D019344:Lactic Acid