Determining Optimal Clothing Ensembles for Military Personnel Conducting Outdoor Activities in Cold Environments

Military and civil defence personnel are often involved in complex and strategic activities in a variety of outdoor environments. Selection of an optimal clothing ensemble for any given environmental condition is therefore essential for unhindered performance. The aim of the present study was to test the suitability of micrometeorological monitoring in relation to eventual local biometeorological forecasting, and their agreement with measured thermophysiological data obtained using predefined clothing ensembles. The overall aim of the research programme is the development of general guidelines for identifying optimal outdoor clothing ensembles for a variety of activities in cold environments. We compared the clothing thermal insulation and observed thermal balance of subjects performing guard duty and a 12 km hike in the winter months of 2006, with the clothing thermal insulation required to maintain thermoneutrality as predicted by biometeorological forecast. The field tests were conducted in Pokljuka (Slovenia), located in the eastern part of the Julian Alps, characterized by temperate alpine climate. These forecasts account for the specific characteristics of the geographical site and of the subjects. The garment ensembles used in the field trials were standard issue for such environmental conditions in the Slovene Armed Forces. During the trials, we monitored skin and core temperature, heart rate, ventilation and metabolic rate. At regular intervals, subjects provided ratings of thermal comfort. The main biometeorological forecast result is represented by an hourly assessment of the clothing insulation range (minimum and maximum values) and was correlated with respective ones obtained from the field trials. The thermal characteristic of the clothing ensembles, namely thermal resistance was determined with a sweating thermal manikin. Preliminary results demonstrate an agreement between the clothing thermal insulation predicted by the biometeorological forecast, and the insulation of the clothing worn during the field trials when thermoneutrality was achieved. This study represents the first step in the development of a comprehensive personalized forecast system, able to manage information provided by physiological models, to improve the level of recommendations regarding the optimal thermal characteristics of clothing ensembles for specific activities. It is envisaged that such forecasting capability incorporating physiological responses will assist in the planning of winter military activities, providing support for decisions regarding logistics and health risk management of individuals involved. This study was supported, in part, by Knowledge for Security and Peace grant administered by the Ministries of Defence, and of Science of the Republic of Slovenia.