Peripheral Thermal Thresholds and Thermoeffectors Threshold Zone in Malaysian and Japanese Males

Heat acclimatization is triggered as a response to a complex of environmental factors in hot climate. A number of studies on heat acclimatization have been reported in terms of physiological adaptation (such as body temperature and sweating responses) (Saat et al., 2005; Saat & Tochihara, 2008), while studies on heat acclimatization in cutaneous thermal sensitivity are relatively rare. It is known that long term changes in a thermal environment can reach the central nervous system either directly, by deviation of core temperature, or indirectly, via thermoreceptors (Hensel, 1982). Cutaneous thermal receptors transmit information about the temperature of the external surface of the body (Iggo, 1970), and mediate the autonomic temperature regulation, and the experiences of thermal comfort and discomfort (Hammel,1968; Hardy, 1961; Hensel, 1982; Nadel et al., 1973). These experiences motivate our thermoregulatory behaviour. The purpose of this study was to investigate: 1) differences in cutaneous warm and cool sensations between Malaysian and Japanese males; 2) peripheral thermoeffector zone estimated from an inter-threshold zone between cool and warm sensations in two ethnic groups.