Applicability of heat stress index in the context of military work: Pilot study

Abstract

This study aimed to understand the thermal stress to which young soldiers of the Portuguese Army are exposed in real working contextas in training or activitiesin hot climates. The main objective is to verify the applicability of heat stress indexes in this work context. The data used was collected by an experimental method carried out in a partnership between the University of Porto and the Portuguese Army. Two stress protocols were performed in two different environmental conditions: thermoneutral (22 °C and 40 RH) and thermal stress (40 °C and 30% RH). In order to verify the influence of the environmental conditions on the body during military march, with (MWL) and without additional load (WNL), measurements of different physiological parameters were performed, which included monitoring of core temperature, heart rate, oxygen consumption, body mass loss and blood lactate concentration. The WBGT, PHS and UTCI indexes are highlighted in the literature, being for this reason selected for this study. As results, the WBGT underestimated the MWL protocols in thermoneutral environment; PHS has been shown to be limited to higher metabolic rates; and the UTCI proved useful for a first environmental assessment. This reflects in a greater emphasis on the indexes in the environment than in individuals. It was verified that the use of these indexes may not be adequate in the military work, performed in a very hot and dry environment, when it includes march with load and high metabolic rate. (c) Springer Nature Switzerland AG 2019.