TY  - JOUR
PY  - 2008//
TI  - Shivering heat production and core cooling during head-in and head-out immersion in 17 degrees C water
JO  - Aviation, space, and environmental medicine
A1  - Pretorius, Thea
A1  - Cahill, Farrell
A1  - Kocay, Sheila
A1  - Giesbrecht, Gordon G.
SP  - 495
EP  - 499
VL  - 79
IS  - 5
N2  - INTRODUCTION: Many cold-water scenarios cause the head to be partially or fully immersed (e.g., ship wreck survival, scuba diving, cold-water adventure swim racing, cold-water drowning, etc.). However, the specific effects of head cold exposure are minimally understood. This study isolated the effect of whole-head submersion in cold water on surface heat loss and body core cooling when the protective shivering mechanism was intact. METHODS: Eight healthy men were studied in 17 degrees C water under four conditions: the body was either insulated or exposed, with the head either out of the water or completely submersed under the water within each insulated/exposed subcondition. RESULTS: Submersion of the head (7% of the body surface area) in the body-exposed condition increased total heat loss by 11% (P < 0.05). After 45 min, head-submersion increased core cooling by 343% in the body-insulated subcondition (head-out: 0.13 +/- 0.2 degree C, head-in: 0.47 +/- 0.3 degree C; P < 0.05) and by 56% in the body-exposed subcondition (head-out: 0.40 +/- 0.3 degree C and head-in: 0.73 +/- 0.6 degree C; P < 0.05). DISCUSSION: In both body-exposed and body-insulated subconditions, head submersion increased the rate of core cooling disproportionally more than the relative increase in total heat loss. This exaggerated core-cooling effect is consistent with a head cooling induced reduction of the thermal core, which could be stimulated by cooling of thermosensitive and/or trigeminal receptors in the scalp, neck, and face. These cooling effects of head submersion are not prevented by shivering heat production.<p /> <p>Language: en</p>
LA  - en
SN  - 0095-6562
UR  - http://dx.doi.org/
ID  - ref1
ER  -