title: The effects of face cooling during hyperthermic exercise in man: evidence for an integrated thermal, neuroendocrine and behavioural response.
abstract: The present study investigated whether face cooling reduced both the perceived exertion (RPE) and prolactin (PRL) release during hyperthermic exercise. Ten, non-heat-acclimated males (23 +/- 2 years; maximal oxygen consumption, 56 +/- 7 ml kg(-1) min(-1) [mean +/- s.d.]) exercised for 40 min on a cycle ergometer at 65% of their peak aerobic power, at an ambient temperature of 33 degrees C (27% relative humidity) with (FC) and without face cooling as a control (CON). With FC, forehead temperature was maintained approximately 6 degrees C lower than CON, while other skin sites were similar or slightly warmer in the FC condition. Rectal temperature increased by approximately 1.5 degrees C with the same time course in both conditions. A relative bradycardia was observed during FC, with heart rate approximately 5 beats min(-1) lower than CON (P < 0.05). Mean plasma lactate was lower during FC (FC, 5.0 +/- 0.3 mmol l(-1); CON, 5.9 +/- 0.3 mmol l(-1); P < 0.05) but no differences were observed for plasma glucose, which remained constant during exercise. Levels of PRL were maintained at 175 +/- 17 mIU l(-1) during exercise for FC, while values for CON increased to a peak of 373 +/- 22 mIU l(-1) so that towards the end of the exercise, for the same rectal temperature, PRL was significantly lower in the FC condition (P < 0.05). Global and breathing RPE were reduced but only towards the end of the 40 min of exercise during FC, whilst subjective thermal comfort was significantly lower during FC (P < 0.05). We confirm the substantial effect that FC has on the secretion of PRL during hyperthermic exercise but show that it makes a relatively small contribution to the perception of effort when compared to the effect of a cool total skin area as occurs with exercise in a thermoneutral environment.
authors.affiliation: School of Sport and Exercise Sciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. t.mundel@bham.ac.uk
authors.forename: Toby
authors.initials: T
authors.lastname: Mündel
authors.forename: Sabrina J
authors.initials: SJ
authors.lastname: Bunn
authors.forename: Paula L
authors.initials: PL
authors.lastname: Hooper
authors.forename: David A
authors.initials: DA
authors.lastname: Jones
mesh_terms: D000328:Adult; D001519:Behavior; D001786:Blood Glucose; D001831:Body Temperature; D001833:Body Temperature Regulation; D003080:Cold Temperature; D018592:Cross-Over Studies; D015444:Exercise; D005145:Face; D006339:Heart Rate; D018882:Heat Stress Disorders / Q000097:blood / Q000503:physiopathology* / Q000517:prevention & control; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009490:Neurosecretory Systems / Q000503:physiopathology*; D010465:Perception; D011388:Prolactin / Q000097:blood; D012119:Respiration; D016037:Single-Blind Method; D013697:Thermosensing; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid; D011388:Prolactin