Abstract:
The multilayered firefighter turn-out gear is not only restrictive to movement but also contributes to increased body rectal temperature, heart rate, and skin temperature by trapping moisture and heat between the layers of the clothing. Firefighter gear fitting more loosely than needed may result in more clothing "pumping," which might result in a more favorable micro-environment during some phases of firefighting. Because of the potential for impaired cognition of the firefighters under stressful conditions, heat stress, and limited time to save victims, it is imperative to understand when cognition is compromised. Recent menthol studies have found a reduced sweat rate when menthol was applied. Firefighters could benefit from a delay in sweat rate because sweating in the high humidity of the micro-environment may lead to hypohydration without the benefit of cooling. The present study had three purposes: 1) to evaluate firefighter gear fit (loose and regular); 2) to assess cognitive responses to 30-minute exposures in 21 °C and 33 °C and 60% RH; and 3) to assess the effects of menthol skin application on local sweat rate in 33 °C. Ten healthy volunteers participated in three trials of 30 minutes each at 21 °C (control, regular fit, loose fit) and three trials at 33 °C (control, regular fit, loose fit). At the beginning and the end of each trial, participants were tested with three cognitive tests: Reaction Time (RT), MATH (MATH), and Memory (MEM). During the menthol study, ten participants exercised twice (menthol and no-menthol treatments, counterbalanced) for 30 minutes followed by 20 minutes passive recovery and then 30 minutes of exercise in 33 °C while wearing firefighter gear. Loose and regular fit had no significant effect (p > 0.05) on firefighters. Individual positive and negative responders were found for cognitive scores based on LSD. Menthol treatment had no effect (p > 0.05) on thermoregulation or sweat production rate. Additional studies are needed to assess the effects of firefighter gear fit and cognition after multiple exposures to heat. In addition, further investigation is needed to assess the effects of a higher menthol concentration on the skin.
