Thermal comfort of soft-shell back protectors for alpine skiing

Introduction In the last few years the soft-shell back protectors have widely replaced the previously used hard-shell protectors. The soft foamed materials used for soft-shell back protectors provide great impact absorption capability due to their pseudo-dilatant behaviour that permits to the protector to be soft under low speed impacts and to become hard for high speed impacts. Moreover, the soft foams provide a better fit over the body and allow manufactures to create perforated structures of the foam pad that can improve the temperature control and moisture management. The aim of this work has been to measure how back-protectors perform, in terms of heating, cooling, moisture management and therefore overall thermal comfort, under controlled environmental conditions. Three different commercial back protectors have been used in order to compare how materials and design can influence the above mentioned thermal properties. Materials/Methods Five testers have tested three types of soft shell back protectors in a climatic chamber in order to evaluate the thermal performances of each back protector. Temperature and humidity sensors, distributed in 11 different body positions, have allowed the measure of the skin mean and torso temperatures and the microclimate humidity and temperature in the zone between the skin and the back-protector. Moreover, the mechanism of heat dissipation has bee studied usingthermo-graphic imaging. The tests have been performed running on a treadmill under controlled physical activity. Both objective and subjective parameters have been analysed, in order to define an appropriate method for the comparison of back protectors with different materials and designs. The physical activity level has been evaluated using an heart rate monitor, while the sweat rate has been used as indication of the thermal stress of the tester. Results and Conclusions. The method developed in this work has allowed a detailed evaluation on how the different types of back protectors influence the thermo-physiological comfort of the final user. The results obtained show minor differences from a global point of view (Average Skin Temperature). However, looking more in detail into the thermal micro-climate locally in the torso area (Average Torso Temperature), the differences are larger still maintaining the same thermal performance hierarchy of the average skin temperature.