Abstract For over 2,000 years, local tissue heating has been used to treat rheumatism, arthritis, muscle strains and sprains, and a variety of other pathologies. Heat can be applied with hot packs, Jacuzzi, ultrasound, diathermy, or lasers. The overall effect is the same. Heat is applied to the surface of the skin in an effort to transfer the heat deep into the tissue. However, there is always a possibility of harmful effects as well as beneficial effects from heating of the skin. Numerous models have been developed including the Pennes Equation to understand how blood flow and skin conductivity are related. However, this model does not take into consideration the effect of central sympathetic outflow on skin thermal conductivity. Therefore, in the present investigation, we examined heat dissipation in the skin on 4 areas on the body in 10 young subjects in a thermally neutral environmental and a warm environment to alter skin sympathetic activity. The results of the experiments showed that if skin thermal conductivity is measured with subjects exposed to a warm environment, heat loss is more pronounced in the skin. Thus in a cold room, hot packs cause a greater change in skin temperature and provide a greater stress on the skin.