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A SUBMAXIMAL STEP TEST OF AEROBIC CAPACITY OVERESTIMATES VO2 IN CAREER FIREFIGHTERS

Abstract

Andrew Mangan1, Blake Landon1, Ryan Warner1, Davis Hale1, Roger Kollock1, Gabriel Sanders2, Will Peveler3, 1University of Tulsa, Tulsa, Oklahoma; 2Northern Kentucky University, Highland Heights, Kentucky; 3Liberty University, Lynchburg, Virginia

Due to the average duration of fire suppression activities, 20-45 minutes repeated 2-4 times per event, and short rest interval (5-10 minutes), there is a reliance on both aerobic and anaerobic (glycolytic) sources of energy. Several studies have reported that firefighters experience heart rate (HR) close to maximum values and a rapid onset of blood lactate accumulation. The cardiorespiratory workload at such intensities creates a significant risk for safety. An acute cardiac event (ACE) is a risk factor for firefighters with low levels of aerobic capacity. Many municipalities require their career firefighters maintain an aerobic capacity of ≥42 mL/kg/min, however, few require a true measure of aerobic capacity and instead rely on submaximal predictive values. PURPOSE: The purpose of this study was to determine the difference between peak VO2and estimated VO2usinga maximal and submaximal step test of aerobic capacity in career firefighters. METHODS: Following IRB approval, 18career male firefighters(age 35.21±8.38 yrs.) completed both the WFI Stepmill Test(maximal)of Aerobic Capacity on a StairMaster Gauntlet series step ergometer and the Forestry Step Test(submaximal). Each test was administered two weeks apart. The difference between the two tests was determined using a paired sample t-test with the significance level set at .05. Prior to data comparisons, a Kolmogorov-Smirnov test of normality was performed and determined the data to be from a normal distribution (WFIVO2: p= .20, Forestry VO2: p= .20).RESULTS: Results from the paired sample t-test indicate a significant difference between the WFI VO2and the Foresty Step Test VO2(WFI: 38.08±6.2 vs Forestry: 43.83±6.8, p= .015). In addition, a post hoc comparison using Cohen’s d indicated a large effect size (.882).CONCLUSION: Results of the current study indicate the Forestry Step Test significantly overestimates VO2 in career fighters by 5.75 mL/kg/min. Such tests of aerobic capacity should be used with caution when determining the aerobic capacity in career firefighters.

ACKNOWLEDGEMENTS: This study was funded by The Oklahoma Center for Advancement of Science and Technology Health Research Grant Program and The University of Tulsa Undergraduate Research Challenge Program.

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