when skin temperature is about 89°F (31°C) or less (Veicsteinas et al., 1982). Thus, during cold exposure, central core temperature defense occurs at the expense of a decline in skin temperature.
The reduction in blood flow and consequent fall in skin temperature contribute to the etiology of cold injuries (Purdue and Hunt, 1986). The hands and fingers are particularly susceptible to cold injury (Boswick et al., 1979) and to a loss of manual dexterity due to cold-induced vasoconstriction (Gaydos, 1958). In these areas of the body, another vasomotor response to cold, cold-induced vasodilation, modulates the effects of vasoconstriction. Figure 7-3 illustrates this response, first described by Lewis (1930), who termed the response the hunting reaction. Periodic oscillations (rise and fall) of skin temperature follow the initial decline in skin temperature during prolonged cold exposure. These skin temperature oscillations are the result of transient increases in blood flow to the cooled finger. Originally thought to be a local effect of cooling (Burton and Edholm, 1955), recent evidence suggests the hunting reaction may involve a centrally-mediated mechanism (Lindblad