Received June 29, 2006
Revised July 26, 2006
Accepted after revision September 12, 2006
Human, Environmental & Exercise [250]
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The Effects of Face-Cooling during Hyperthermic Exercise: Evidence for an Integrated Thermal, Neuroendocrine and Behavioural Response
Toby Mundel 1*,
Sabrina J Bunn 1,
Paula L Hooper 1,
David A Jones 2
1 The University of Birmingham
2 The University of Birmingham, Manchester Metropolitan University
* To whom correspondence should be addressed. E-mail: t.mundel{at}bham.ac.uk.
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Abstract |
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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; VO2max: 56 ± 7 ml kg-1 min-1 [mean ± SD]) exercised for 40 min on a cycle ergometer at 65% of their peak aerobic power, at an ambient temperature of 33°C (27% relative humidity) with (FC) and without face-cooling as a control (CON). With FC, forehead temperature was maintained ~6°C lower than CON while other skin sites were similar or slightly warmer in the FC condition. Rectal temperature increased by ~1.5°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, 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 thermo-neutral environment.
Key Words:
Exercise, Hyperthermia, Prolactin
