Open AccessThe effects of head cooling on endurance and neuroendocrine responses to exercise in warm conditions
Author(s) -
Les Ansley,
Garry Marvin,
Ashwani Sharma,
M. J. Kendall,
David A. Jones,
Matthew Bridge
Publication year - 2008
Publication title -
physiological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.647
H-Index - 70
eISSN - 1802-9973
pISSN - 0862-8408
DOI - 10.33549/physiolres.931260
Subject(s) - thermoregulation , medicine , hyperthermia , endurance training , serotonergic , physical exercise , endocrinology , serotonin , receptor
The present study investigated the effects of head cooling duringendurance cycling on performance and the serotonergicneuroendocrine response to exercise in the heat. Subjectsexercised at 75 % VO2max to volitional fatigue on a cycleergometer at an ambient temperature of 29±1.0 °C, with arelative humidity of approximately 50 %. Head cooling resulted ina 51 % (p<0.01) improvement in exercise time to fatigue andBorg Scale ratings of perceived exertion were significantly lowerthroughout the exercise period with cooling (p<0.01). Therewere no indications of peripheral mechanisms of fatigue eitherwith, or without, head cooling, indicating the importance ofcentral mechanisms. Exercise in the heat caused the release ofprolactin in response to the rise in rectal temperature. Headcooling largely abolished the prolactin response while having noeffect on rectal temperature. Tympanic temperature and sinusskin temperature were reduced by head cooling and remainedlow throughout the exercise. It is suggested that there is a coordinated response to exercise involving thermoregulation,neuroendocrine secretion and behavioural adaptations that mayoriginate in the hypothalamus or associated areas of the brain.Our results are consistent with the effects of head cooling beingmediated by both direct cooling of the brain and modifiedcerebral artery blood flow, but an action of peripheralthermoreceptors cannot be excluded.