Evaluation of physiological and psychophysical strain of security guards wearing stab-resistant body armor under a simulated patrol condition

This study aimed to determine the effects of stab-resistant body armor (SRBA) on the physiological and psychophysical strain of security guards. Ten volunteers performed a 50-min treadmill walk at 7.0 km/h in a climate chamber where the ambient temperature and relative humidity were controlled to 40 °C and 40%, respectively. All the participants performed the walk under two experimental conditions: wearing a uniform without (CON) and with armor (SRBA). Several physiological responses (core temperature, skin temperature, heart rate, and oxygen consumption) and psychophysical parameters (thermal sensation vote, thermal comfort vote, ratings of perceived exertion, and clothing and skin wetness) were recorded during the trials. Furthermore, the sweat loss, body heat storage, and physiological strain index (PSI) were calculated based on the measurements. The results indicated no significant difference between the SRBA and CON groups in terms of core temperature, mean skin temperature, heart rate, oxygen consumption, body heat storage, or PSI over time. However, a significant difference (p < 0.05) between the two trials was observed in terms of scapula skin temperature (40 and 45 min) and body temperature (0 and 45 min). Moreover, the SRBA (3.5 kg and 17% body area coverage) caused an 11% increase in sweat loss, but a 27% reduction in sweating efficiency. Although the armor caused slight discomfort, wetness, and exertion, no significant difference between the two trials was observed in terms of the psychophysical responses. Therefore, the SRBA imposed negligible physiological and psychophysical strain during the 50-min walk in this case.