Fire Service instructors undergarment choice to reduce interleukin-6 and minimise physiological and perceptual strain

Fire Service Instructors frequently experience high levels of physiological and perceptual strain during live fire exposures. Instructors are also at risk of cardiovascular illnesses, with cardiac death being the greatest cause of fire fighter death. Current practice for UK instructors is to select undergarment type based on personal preference, between a boiler suit (BOILER) and a wicking base layer (WBL). Research suggests that shorts and t-shirt (SHORTS) may also be a beneficial alternative undergarment choice. The UK South East Fire Service requested an investigation to identify if undergarment selection can lessen the strain experienced by instructors, and reduce the acute inflammatory response to fire exposures. Eight males completed three 45min sessions in a heat chamber (49.5 ± 1.4°C and 16.9 ± 4.3% RH) whilst performing intermittent walking. At the end of heat exposure change in heart rate was not effected by garment type ( p=0.061,ηp2=0.373). Change in rectal temperature was different between garments (p=0.009,ηp2= 0.271), with trends suggesting that BOILER resulted in a greater change (1.03 ± 0.60°C) than SHORTS (0.76 ± 0.37°C,p=0.589,d=0.21) and WBL (0.72 ± 0.33°C,p=0.545,d=0.25). Interleukin-6 post exposure was greater for BOILER (6.96 ± 0.28pg.mL-1) than both SHORTS (6.59 ± 0.30pg.mL-1,p=0.043,d=0.42) and WBL (6.45 ± 0.43pg.mL-1,p=0.031,d=0.51). Overall, undergarment type had little impact on physiological or perceptual strain. However, wearing WBL or SHORTS may reduce the inflammatory response, and consequently decrease the risk of cardiovascular events.