Dynamic thermal receptor response and comfort in cold and warm environments

Introduction Athletes are permanently exposed to or in the state of transient thermal conditions, because of their own varying metabolic output or environmental factors such as temperature, humidity, wind velocity and radiation. This causes thermal stress, discomfort and even inhibits performance. The human body constantly regulates its internal temperature receiving neuronal signals from thermal receptors in the skin. Both warm and cold receptors have static and dynamic responses to thermal transitions in the environment. The latter occurs at sudden thermal changes that lead to peak the receptors firing rate. It is well known how humans thermally perceive transient thermal conditions due to starting temperature, temperature gradient and the size of the skin surface area. Not known is their comfort response to quick environmental changes. Therefore this study investigates local comfort response of sudden thermal changes, whether they can improve thermal comfort and imply useful applications for hot or cold environments in sports. Methodology Eight healthy, male subjects were exposed to three warm and cold environments in standardized clothing. After 20 minutes of acclimatization nine body parts were locally treated with cool and warm convection to trigger peak receptor responses ("overshoot"). Local skin temperatures were measured and subjects were asked about their thermal comfort and perception. Results Results show highly significant global comfort improvement by local overshoot in both environments (p=.00, α= 01) at every body part. Furthermore results show tendencies for major impact on comfort of core body parts. Conclusion To sum up this research found the possibility for temporal local treatment as highly efficient for significant comfort improvement. For instance local heating via technical textiles can improve comfort in harsh skiing conditions or local cooling can do the same in extreme heat. Nonetheless further research is needed to quantify physiological impacts of temporal local treatments for further implications e.g. on sports performance as well as possibilities of technical realizations.