Physiological Responses During Graded Treadmill Exercise in Chemical-Resistant Personal Protective Equipment

Abstract

Background. As the likelihood of terrorist acts increases, prehospital personnel have been forced to train in the proper use of chemical-resistant personal protective equipment (PPE). This protective ensemble has been reported to be physiologically taxing for the wearer, imposing an additional thermal load resulting in hypohydration, hyperthermia, andreduced work time. Victim extrication, the rescue-the-rescuer role of the rapid intervention team andrapid self-extrication, typically requires high-intensity work that can be maintained only for short time intervals. The additional physiological burden imparted by the level C PPE during high-intensity work is unknown. Objective. We hypothesized that the added thermal burden resulting from work in PPE would shorten work time andresult in a higher core temperature during incremental treadmill exercise. Method. In this prospective, crossover, laboratory study, EMS providers (n = 8, 5 male) completed a Bruce treadmill test on two occasions: once in a chemical-resistant coverall andair-purifying respirator (PPE) andonce in shorts andt-shirt (CON). Oxygen consumption, vital signs, core andskin temperature, andperceptual measures of exertion, thermal sensation, andcomfort were monitored throughout the test. Results. Subjects achieved maximal oxygen consumption andmore than 90% of age-predicted maximum heart rate in both conditions. Heart rate, skin temperature, andmeasures of perceived exertion, comfort, andthermal sensation increased during the treadmill exercise but did not differ between the PPE andCON conditions. Core temperature increased in both the CON andPPE conditions (0.8 ± 0.5 vs. 0.7 ± 0.3, p = 0.40). Conclusion. High-intensity work in level C PPE is primarily limited by cardiovascular capacity. The thermal burden associated with this short bout of work in PPE (approximately 10 minutes) is not different than high-intensity work in short pants andcotton t-shirt. Consideration should be given to cardiorespiratory fitness when assigning providers to work in chemical-resistant PPE, especially on tasks that require high-intensity work.