Integration Between the Environmental Stress Index (ESI) and the Physiological Strain Index (PSI) as a Guideline for Training

Abstract : In this study, we integrate between two new indices for strain and stress assessment into an easy-to-use visualized table. The integration between these two indices can serve as a guideline that should be easy to interpret and to implement for soldiers during training in order to prevent heat casualties. The shortcoming of this work is the strain evaluation by PSI(sub HR). In our previous works, we emphasize the importance of strain evaluation by the cardiovascular and the thermoregulation systems presented by T(sub c) and HR, whereas in this study we only use PSI(sub HR) for strain assessment. We still believe that for more accurate strain assessment we should use PSI. However, under various circumstances and in some scenarios, T(sub c) measurement is not practical or convenient. Therefore, only HR measurement that immediately represents the metabolic rate and the strain reflected by the cardiovascular system can be used for strain assessment. In addition, HR is easier to measure, is easier to implement and it can be measured by the individual himself Since the purpose of this work is to develop guidelines for work-rest cycles in order to help in preventing heat casualties from excessive heat, we should expect a practical and easy-to-use guideline. We believe that the PSI(sub HR) component can serve as a suitable alternative for PSI in circumstances where T(sub c) measurement cannot be taken. The suggested matrix based on PSI(sub HR) and ESI is an attempt to give the decision maker an easy tool to use as a guideline. However, since this is the first study regarding the integration of PSI and ESI, further studies should be made which consider different levels of physical fitness, types of clothing, hydration status, and acclimatization. In addition, it is expected to implement the suggested matrix for fluid replacement quantities.