Application of the Physiological Strain Index (PSI) for Evaluation of Simulated Military Activities
Abstract
The Physiological Strain Index (PSI) (24) is a scale for measuring physiological strain in spontaneous response to work and heat stress using heart rate and core temperature. Previous PSI studies were conducted in controlled laboratory conditions. The purpose of this study was to examine if PSI patterns were different during field activities. In addition, whether intensities of activities, times of activities, types of movements in same activities, and environmental stress affect PSI levels were investigated. Twelve male volunteers (age: 26 +/- 4.0 SD yr; ht: 181 +/- 4 cm; and wt: 80.4 +/- 10.5 kg) participating in U.S. Marine Corps (USMC) infantry training at Quantico, VA, were studied. The PSI was calculated from measured heart rates and core temperatures during field activities. Five activities: firing, attack, preparation, meeting, moving--with at least four participants per activity were used in this study. These activities were further classified as "day" or "night" according to the times the activities occurred. Types of movement in attacks and moving activities were categorized as either "mechanized" or "non-mechanized," depending on whether vehicles were used. The Environmental Stress Index (ESI) (22), which summarizes the influence of air temperature, solar radiation, and relative humidity, was also calculated for the field conditions. Fisher's exact tests were conducted to examine if the PSI levels varied for activities, times of activities, types of movements, and ESI. The PSI levels were different for various activities. Fighting activities (firing and attack), in particular, attained high PSI levels with greater variability than non-fighting activities (p<0.05). PSI levels were high during nighttime as compared to daytime fighting activities (p<0.05). PSI levels in mechanized activities were not statistically different from those in non-mechanized activities (p>0.05). High ESI levels were associated with low PSI levels, and vice versa (p<0.05). 7
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2002
- Accession Number
- ADA408496
Entities
People
- M. Yokota
- Mark J. Buller
- R. W. Hoyt
- William J. Tharion
Organizations
- United States Army Research Institute of Environmental Medicine