Physiological work demands of Spanish wildland firefighters during wildfire suppression
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The aim of this study was to analyze the physiological demands and thermal strain of wildland firefighters during real wildfire suppression.
The response of core temperature and heart rate (HR) were analyzed in 200 wildland firefighters during wildfire suppression activities of different duration: <1 h (n = 52), 1–3 h (n = 70), 3–5 h (n = 44), and >5 h (n = 34). The exercise workload (TRIMP), the physiological strain index (PSI), and cumulative heat strain index (CHSI) were calculated using the time spent in different intensity zones, the HR, and core temperature.
Mean HR was significantly higher (P < 0.05) in wildfires <1 h (133 ± 2 bpm) and 1–3 h (128 ± 1 bpm) versus 3–5 h (120 ± 3 bpm) and >5 h (116 ± 32 bpm). The time spent in higher intensity zones increased (P < 0.05) when wildfire duration increased. TRIMP accumulation increased with wildfire duration (54.9 ± 3.2, 167.4 ± 5.9, 296.0 ± 8.3, 511.7 ± 12.8 in <1, 1–3, 3–5, and >5 h, respectively). Neither core temperature (37.4 ± 0.1°C) nor PSI (4.5 ± 0.2) were influenced by wildfire duration. The CHSI increased (p < 0.05) in the following order: <1 h (104 ± 23), 1–3 h (1,396 ± 275), 3–5 h (4,586 ± 387), and >5 h (10,703 ± 710).
The results demonstrate the high work strain sustained by Spanish wildland firefighters during wildfire suppression. Both workload and CHSI increased with the wildfires duration although the pace of work was faster in wildfires of a shorter duration.
KeywordsHeart rate Core temperature Exercise intensity Workload Thermal strain
This work has been funded by Empresa de Transformación Agraria, SA. (TRAGSA), Mutua Fraternidad–Muprespa and Empresa de Gestión Medioambiental, SA. (EGMASA). This study was conducted with the collaboration of the Área de Defensa contra Incendios Forestales, Dirección General de Medio Natural y Política Forestal, Ministerio de Medio Ambiente y Medio Rural y Marino, Spain.
Conflict of interest
The authors declare that they have no conflict of interest.
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