A practical cooling strategy for reducing the physiological strain associated with firefighting activity in the heat

Abstract

The aim of this study was to establish whether a practical cooling strategy reduces the physiological strain during simulated firefighting activity in the heat. On two separate occasions under high ambient temperatures (49.6 ± 1.8°C, relative humidity (RH) 13 ± 2%), nine male firefighters wearing protective clothing completed two 20-min bouts of treadmill walking (5 km/h, 7.5% gradient) separated by a 15-min recovery period, during which firefighters were either cooled (cool) via application of an ice vest and hand and forearm water immersion (∼19°C) or remained seated without cooling (control). There was no significant difference between trials in any of the dependent variables during the first bout of exercise. Core body temperature (37.72 ± 0.34 vs. 38.21 ± 0.17°C), heart rate (HR) (81 ± 9 vs. 96 ± 17 beats/min) and mean skin temperature (31.22 ± 1.04°C vs. 33.31 ± 1°C) were significantly lower following the recovery period in cool compared with control (p < 0.05). Core body temperature remained consistently lower (0.49 ± 0.02°C; p < 0.01) throughout the second bout of activity in cool compared to control. Mean skin temperature, HR and thermal sensation were significantly lower during bout 2 in cool compared with control (p < 0.05). It is concluded that this practical cooling strategy is effective at reducing the physiological strain associated with demanding firefighting activity under high ambient temperatures.

Keywords:

• firefighter
• heat stress
• recovery strategy
• core temperature

Acknowledgements

The authors are grateful to Merseyside Fire and Rescue Services for their financial support and to firefighting personnel who volunteered to participate in this study. We would also like to thank Station Manager, Paul Murphy for his valued assistance during this study.