THE EFFECT OF VENTED HELMETS ON HEAT STRESS DURING WILDLAND FIREFIGHTER SIMULATION
J. Knight, S. Gurney, K. Christison, T. Burden, J. Long, M. Martin, S. Hilden, C. Dumke FACSM.
University of Montana, Missoula, MT
Uncompensable heat strain from Wildland firefighter (WLFF) personal protective equipment (PPE) decreases the physiological tolerance one can endure while exercising in the heat. PURPOSE: This study compares heat accumulation at simulated working conditions while wearing standard non-vented WLFF helmets (H) versus a vented helmet (VH). METHODS: Ten male subjects with a VO2maxof 59.8 ± 3.6 ml/kg/min completed two trials. Following a 10 minute acclimation period, subjects walked for 180 minute (at 3.5 mph, 5% grade) in a heat chamber (35℃and 30% relative humidity) with three intervals of 50 minutes of exercise and 10 minutes of rest. Separated by two weeks, subjects randomly performed the opposing helmet trial. Each trial measured physiological strain index (PSI), visual analog scale (VAS), helmet temperature and relative humidity (Th, Rh), rating of perceived exertion (RPE) and heart rate (HR). Data was analyzed using a 2X6 repeated measures ANOVA. RESULTS: All subjects finished all trials. At the end of the 3 hour trial HR (146.8±17.2 bpm H, 144.3±17.9 bpm VH), PSI (6.08±1.45 H, 5.89±1.24 VH), RPE (14.2±1.7 H, 13.3±1.7 VH), Th (35.52±.47°C H, 35.75±.50°C VH), and Rh (45.6±5.1% H, 41.0±5.9% VH) showed a significant effect of time (pCONCLUSION:While these physiological variables (HR, VAS, PSI, RPE, Th, and Rh) did not reach trial significance, trends for RPE, helmet microenvironment, and VAS suggest greater heat dissipation and comfort with the vented helmet. This suggests the standard unvented WLFF helmet may contribute to heat gain over time, which may contribute to work output and safety in the field.
Supported by the USFS (18-CR-11138100-005).
Knight, J; Gurney, S; Christison, K; Burden, T; Long, J; Martin, M; Hilden, S; and Dumke, FACSM, C
"THE EFFECT OF VENTED HELMETS ON HEAT STRESS DURING WILDLAND FIREFIGHTER SIMULATION,"
International Journal of Exercise Science: Conference Proceedings: Vol. 8:
7, Article 80.
Available at: https://digitalcommons.wku.edu/ijesab/vol8/iss7/80