title: Firefighter feedback during active cooling: a useful tool for heat stress management?
abstract: Monitoring an individual's thermic state in the workplace requires reliable feedback of their core temperature. However, core temperature measurement technology is expensive, invasive and often impractical in operational environments, warranting investigation of surrogate measures which could be used to predict core temperature. This study examines an alternative measure of an individual's thermic state, thermal sensation, which presents a more manageable and practical solution for Australian firefighters operating on the fireground. Across three environmental conditions (cold, warm, hot & humid), 49 Australian volunteer firefighters performed a 20-min fire suppression activity, immediately followed by 20 min of active cooling using hand and forearm immersion techniques. Core temperature (Tc) and thermal sensation (TS) were measured across the rehabilitation period at five minute intervals. Despite the decline in Tc and TS throughout the rehabilitation period, there was little similarity in the magnitude or rate of decline between each measure in any of the ambient conditions. Moderate to strong correlations existed between Tc and TS in the cool (0.41, p<0.05) and hot & humid (0.57, p<0.05) conditions, however this was resultant in strong correlation during the earlier stages of rehabilitation (first five minutes), which were not evident in the latter stages. Linear regression revealed TS to be a poor predictor of Tc in all conditions (SEE=0.45-0.54°C) with a strong trend for TS to over-predict Tc (77-80% of the time). There is minimal evidence to suggest that ratings of thermal sensation, which represent a psychophysical assessment of an individual's thermal comfort, are an accurate reflection of the response of an individual's core temperature. Ratings of thermal sensation can be highly variable amongst individuals, likely moderated by local skin temperature. In account of these findings, fire managers require a more reliable source of information to guide decisions of heat stress management.
authors.affiliation: Human Performance Science, 1/109 Park St, South Yarra, 3141 Victoria, Australia. Electronic address: robbie@hpscience.com.au.
authors.forename: Robbie J
authors.initials: RJ
authors.lastname: Savage
authors.affiliation: Centre for Physical Activity & Nutrition Research, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia. Electronic address: clor@deakin.edu.au.
authors.forename: Cara
authors.initials: C
authors.lastname: Lord
authors.affiliation: Centre for Physical Activity & Nutrition Research, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia. Electronic address: bllars@deakin.edu.au.
authors.forename: Brianna L
authors.initials: BL
authors.lastname: Larsen
authors.affiliation: Country Fire Authority, 8 Lakeside Dr, Burwood East, 3151 Victoria, Australia. Electronic address: t.knight@cfa.vic.gov.au.
authors.forename: Teagan L
authors.initials: TL
authors.lastname: Knight
authors.affiliation: Country Fire Authority, 8 Lakeside Dr, Burwood East, 3151 Victoria, Australia. Electronic address: p.langridge@cfa.vic.gov.au.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Langridge
authors.affiliation: Centre for Physical Activity & Nutrition Research, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia. Electronic address: brad.aisbett@deakin.edu.au.
authors.forename: Brad
authors.initials: B
authors.lastname: Aisbett
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D005246:Feedback; D061388:Firefighters; D018882:Heat Stress Disorders / Q000517:prevention & control*; D006358:Hot Temperature; D006801:Humans; D008875:Middle Aged; D012044:Regression Analysis; D012881:Skin Temperature / Q000502:physiology; D013312:Stress, Physiological / Q000502:physiology*; D013696:Temperature; D055815:Young Adult
keywords: Core temperature; Firefighting; Heat stress management; Thermal sensation