Physiological and perceptual responses of firefighters wearing protective clothing under various training environment and activity conditions

To enhance operational capabilities of firefighters in live-fire scenarios, daily training is absolutely important which involves various types of training tasks in diverse thermal environments. Fire training in heat may impose severe heat stress on firefighters. Yet, the thermal burden associating with different training has rarely been studied. In this study, twelve healthy male firefighters performed 50 min of treadmill exercise while wearing firefighting protective clothing (FPC) in two environmental conditions (34 °C and 37 °C) with three training intensities (3 km/h, 4.5 km/h and 6 km/h). Results showed that in hot environments, training intensity exhibited a more pronounced effect on physiological responses than ambient temperature. Exposure to 37 °C with heavy activity produced high level of core temperature (38.8 ± 0.2 °C), near maximal heart rate (164±18 bpm), increased energy expenditure (27.10±1.42 ml/min/kg) coupled with mild dehydration (2.08%±0.35%). The forehead, back and chest which showed the highest level of thermal sensation vote, wetness sensation vote and thermal comfort vote are suggested to be primarily considered when designing cooling strategies. Moreover, when providing recovery and cooling for firefighters working in extreme heat while wearing fully encapsulated FPC, the priority should be given to work intensity and duration, followed by environmental conditions.