Abstract
Fire suppression and rescue is a physiologically demanding occupation due to extreme external heat as well as the physical and thermal burden of the protective garments. These conditions challenge body temperature homeostasis and results in heat stress. Accurate field assessment of core temperature is complex and unreliable. The present investigation developed a perceptually based hyperthermia metric to measure physiologic exertional heat strain during treadmill exercise. Sixty-five (28.9 ± 6.8 years) female (n = 11) and male (n = 54) firefighters and non-firefighting volunteers participated in four related exertional heat stress investigations performing treadmill exercise in a heated room while wearing thermal protective clothing. Body core temperature, perceived exertion, and thermal sensation were assessed at baseline, 20-mins exercise, and at termination. Perceived exertion increased from baseline (0.24 ± 0.42) to termination (7.43 ± 1.86). Thermal sensation increased from baseline (1.78 ± 0.77) to termination (4.50 ± 0.68). Perceived exertion and thermal sensation were measured concurrently with body core temperature to develop a two-dimensional graphical representation of three exertional heat strain zones representative of a range of mean body core temperature responses such that low risk (green) incorporated 36.0–37.4°C, moderate risk (yellow) incorporated 37.5–37.9°C, and high risk (red) incorporated 38.0 to greater than 40.5°C. The perceptual hyperthermia index (PHI) may provide a quick and easy momentary assessment of the level of risk for exertional heat stress for firefighters engaged in fire suppression that may be beneficial in high-risk environments that threaten the lives of firefighters.
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Acknowledgments
The authors would like to acknowledge the Federal Emergency Management Agency Assistance to Firefighters Grant Program (EMW-2006-FP-02245) for funding the FIRE I and FIRE II studies. This study was also supported in part by Grant Number UL1 RR024153 from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. The contents of this manuscript are solely the responsibility of the authors and do not necessarily represent the official view of FEMA, NCRR, or NIH. We would also like to thank our participants and the assistance of Jamey Bednez, Sarah Kerin, Julia Morley and Gillian Beauchamp in data collection.
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Communicated by Narihiko Kondo.
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Gallagher, M., Robertson, R.J., Goss, F.L. et al. Development of a perceptual hyperthermia index to evaluate heat strain during treadmill exercise. Eur J Appl Physiol 112, 2025–2034 (2012). https://doi.org/10.1007/s00421-011-2173-z
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DOI: https://doi.org/10.1007/s00421-011-2173-z