Burn Injury Does Not Exacerbate Heat Strain during Exercise while Wearing Body Armor

Abstract

Introduction Although evaporative heat loss capacity is reduced in burn-injured individuals with extensive skin grafts, the thermoregulatory strain due to a prior burn injury during exercise-heat stress may be negligible if the burn is located underneath protective clothing with low vapor permeability. Purpose This study aimed to test the hypothesis that heat strain during exercise in a hot–dry environment while wearing protective clothing would be similar with and without a simulated torso burn injury. Methods Ten healthy individuals (8 men/2 women) underwent three trials wearing: uniform (combat uniform, tactical vest, and replica torso armor plates), uniform with a 20% total body surface area simulated torso burn (uniform + burn), or shorts (and sports bra) only (control). Exercise consisted of treadmill walking (5.3 km·h−1; 3.7% ± 0.9% grade) for 60 min at a target heat production of 6.0 W·kg−1 in 40.0°C ± 0.1°C and 20.0% ± 0.6% relative humidity conditions. Measurements included rectal temperature, heart rate, ratings of perceived exertion (RPE), and thermal sensation. Results No differences in rectal temperature (P ≥ 0.85), heart rate (P ≥ 0.99), thermal sensation (P ≥ 0.73), or RPE (P ≥ 0.13) occurred between uniform + burn and uniform trials. In the control trial, however, core temperature, heart rate, thermal sensation, and RPE were lower compared with the uniform and uniform + burn trials (P ≤ 0.04 for all). Conclusions A 20% total body surface area simulated torso burn injury does not further exacerbate heat strain when wearing a combat uniform. These findings suggest that the physiological strain associated with torso burn injuries is not different from noninjured individuals when wearing protective clothing during an acute exercise-heat stress.

Thermoregulatory Responses with Size-matched Simulated Torso or Limb Skin Grafts

“…Body armor, which is worn on the torso to protect against ballistic and fragmentation injury to vital organs, impedes evaporative heat loss from covered areas of the torso surface (39). For this reason, the presence of a torso burn injury does not further reduce whole-body heat loss compared with noninjured individuals when body armor is worn (40). In other words, both torso-burned and nonburned individuals rely heavily on nontorso skin (i.e., limbs and head) for heat loss when body armor is worn.…”

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

“…The effects of body armor on thermal responses and physiological strain (e.g., body temperature, heart rate, metabolic rate, respiratory exchange ratio, and sweat loss) have been reported in several studies. [10][11][12][13][14][15][16][17] The core temperature and maximum working time while wearing body armor were predicted by means of a mathematical model using biophysical characteristics measured by a thermal manikin. 11 Body armor significantly increased oxygen uptake, blood lactate, heart rate, and ratings of perceived physical exertion.…”