J. Jacobs, K. Uhlenkott, M. Slater, M. Akers, K. Pfaffenbach

Eastern Oregon University, La Grande, OR

Wildland firefighting is a job that requires strength and stamina. The Grande Ronde Rappellers (GRR) are highly-trained aerially delivered firefighters that provide ‘initial attack’ on forest fires. Rappellers are often ‘on’ fires for 72 hours, where they work physically active shifts ranging from 4-16 hours, and then are required to ‘pack out’ across 5-15+ miles of mountainous terrain carrying loads in excess of 50 kg. Few studies have examined the cardiometabolic fitness and efficiency of wildland firefighters, and no studies to our knowledge have examined members of a USFS rappel crew. PURPOSE: To examine the heart rate, oxygen consumption, and rate of caloric use of GRR firefighters during a 4 stage metabolic test. METHODS: Each subject underwent a metabolic test with four consecutive 6-minutes stages (24 minutes total) that included sitting, walking on a treadmill at 4mph, walking on a treadmill at 4mph with a 6-8% incline, and walking on an inclined treadmill at 4mph while wearing a 20.45kg vest. Heart Rate (bpm) and VO2 (ml/kg/min) were measured throughout the test. Respiratory Exchange Ratio (RER) and kilocalories burned (kcal/min) were calculated for each stage. Data from stages was analyzed using ANOVA. RESULTS: Male (n=13) and female (n=2) subjects tested were aged 30.47±3.56 years, weighed 85.12±10.90 kg, and had a mean body fat % of 17.35±4.80. Mean HR (bpm) was different for the sitting, walking, incline, and weighted incline stages were 67.00±9.9, 99.71±12.71, 118.29±13.27, and 146.07±9.62, respectively (p<0.05). Mean VO2 (ml/kg/min) for each of the 4 stages was 3.47±1.01, 18.51±2.37, 24.98±2.18, and 33.55±4.49 (p<0.05). Mean oxidative caloric use rates (kcal/hr) were 86.35±31.15, 454.50±81.79, 622.12±93.64, and 850.77±156.83 (p<0.05). RER for each state was 0.87±0.10, 0.81±0.05, 0.88±0.03, and 0.92±0.02. CONCLUSION: This study provided insights into oxidative energy use and substrate utilization in highly skilled wildland firefighters.

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