Tissue heat transfer in water: lessons from the Korean divers

The factors which influence tissue heat transfer and temperature gradients from body core to skin surface are reviewed in the context of studies on Korean diving women. The resistance to heat transfer imposed by resting muscle is shown to be 2-3 times as great as that imposed by overlying fat and skin. However, exercising muscle imposes very little resistance to heat flux because of the increase in convective heat transfer. Accordingly, the limiting resistance to heat flow is shifted to subcutaneous fat and skin during exercise in cold water. Hypothetical examples are given of how important the subcutaneous fat can be in maintaining a high core-to-water temperature gradient in cold water and the same validated by examples from the literature. Last, hypothetical examples are given of the role cutaneous blood flow must play in controlling heat flux and temperature gradients across the subcutaneous fat layer.