Association between physiological and perceptual heat strain while wearing stab-resistant body armor.

In this study, we explored the association between physiological and perceptual heat strain while wearing stab-resistant body armor (SRBA). Human trials were performed on ten participants in warm and hot environments. Physiological responses (core temperature, skin temperature, and heart rate), and perceptual responses (thermal sensation vote, thermal comfort vote, restriction of perceived exertion (RPE), wetness of skin, and wetness of clothing) were recorded throughout the trials, and subsequently, the physiological strain index (PSI), and perceptual strain index (PeSI) were calculated. The results indicated that the PeSI showed a significant moderate association with the PSI, and was capable of predicting PSI for low (PSI = 3) and high (PSI = 7) levels of physiological strain with the areas under the curves of 0.80 and 0.64, respectively. Moreover, Bland-Altman analysis indicated that the majority of the PSI ranged within the 95% confidence interval, and the mean difference between PSI and PeSI was 0.14 ± 2.02 with the lower 95% limit and upper 95% limit being -3.82 to 4.10, respectively. Therefore, the subjective responses could be used as an indicator for predicting physiological strain while wearing SRBA. This study could provide fundamental knowledge for the usage of SRBA, and the development of physiological heat strain assessment.

Physiological and perceptual responses while wearing stab-resistant body armor in hot and humid environment.

The aim of this study was to investigate the physiological and perceptual responses of the human body wearing stab-resistant body armor (SRBA) in a hot and humid environment. The responses of five healthy male volunteers wearing SRBA were compared with those under a Control condition (wearing T-shirt) in a hot and humid environment (38 °C and relative humidity of 60%). The participants walked on a treadmill at a speed of 6 km/h for 60 min and this was followed by 60 min of recovery. The physiological responses (core temperature, skin temperature, heart rate, oxygen consumption) and perceptual parameters (thermal sensation, thermal comfort, rate of perceived exertion (RPE), and restriction to movement) were recorded throughout the tests. The results showed that the use of SRBA resulted in higher values of core temperature, mean skin temperature, heart rate, and oxygen consumption during exercise, and a significant difference (p < 0.05) between the SRBA and Control trials in terms of oxygen consumption was observed. The subjects wearing SRBA exhibited higher RPE and restriction to movement during exercise when compared with those in the Control condition, and a significant difference (p < 0.05) between the two trials in terms of restriction to movement was observed. Moreover, no significant differences (p > 0.05) in terms of thermal sensation and thermal comfort were observed between the SRBA and Control trials. It was concluded that the use of SRBA imposed high thermoregulatory and cardiovascular strain, reduced perceived exertion, and restricted movement during exercise in the hot and humid environment, whereas its effect on thermal sensation and thermal comfort was negligible when compared with those in the Control condition.

Effects of a liquid cooling vest on physiological and perceptual responses while wearing stab-resistant body armor in a hot environment.

This study determines the effects of a liquid cooling vest (LCV) on physiological and perceptual responses while wearing stab-resistant body armor (SRBA). Ten healthy male volunteers wearing SRBA performed human trials with the LCV and without (control) in a hot environment (30 °C and 40% relative humidity). Physiological parameters and perceptual responses were recorded during the tests. The results indicated that the difference in the mean skin temperature and scapula skin temperature between the two conditions was up to 1.2 and 2.5 °C, respectively. The LCV did not significantly decrease the core temperature, heart rate, sweat loss, oxygen consumption, rating of perceived exertion and restriction of movement. However, a significant difference was observed between conditions in terms of evaporation efficiency and thermal sensation. Therefore, the LCV attenuated an increase in thermal sensation but did not mitigate physiological strain. This work can provide fundamental knowledge for high-performance personal cooling system development.