Discussion of “Core cooling and thermal responses during whole-head, facial, and dorsal immersion in 17 °C water”

Abstract

1. The rate of oesophageal temperature reduction and the heat loss from the head were less in the second 30 min of cooling than in the first 30 min. This was despite no increase in metabolic rate and a lessening in the rate of vasoconstriction (going by the slope of fingertip blood flow and the change in fingertip temperature). Is the extent of vasoconstriction (even though the rate was lessening) sufficient to explain the reduced rate of oesophageal temperature reduction and heat loss in the second 30 min? Or is there something else going on which slowed up the heat loss? 2. With regard to the core cooling increase with facial compared to dorsal immersion, could some of the difference also be attributable to airway heat loss? With facial cooling, presumably part of the snorkel tubing passed through the water which may have meant that the inspired air was cooler than in the facial cooling condition where perhaps none of the snorkel tubing was in the water.