Differences in Workloads of Maximal Tasks in Active-Duty Firefighters

The purpose of this study was to compare the workload of a maximal treadmill test (TREAD) and a fire suppression task (BURN) in firefighters and to examine their relationships to fitness as measured by body mass index (BMI), percent body fat (BF%), and peak aerobic capacity (VO_2PEAK). The amount of time spent in the heart rate (HR) intensity ranges of 50-59% HR_MAX (ZONE1), 60-69% HR_MAX (ZONE2), 70-79% HR_MAX (ZONE3), 80-89% HR_MAX (ZONE4), and ≥90% HR_MAX (ZONE5) quantified the workload as the Edward's Training Impulse for TREAD (ETRIMP_TREAD) and BURN (ETRIMP_BURN). The ETRIMP_TREAD was significantly less than ETRIMP_BURN. For TREAD, ZONE5 > ZONE2 and ZONE3. For BURN, ZONE4 > ZONE1, ZONE2, and ZONE5 > ZONE1, ZONE2, and ZONE3. A lower BF% and greater VO_2PEAK were related to a greater ETRIMP_TREAD and unrelated to ETRIMP_BURN. For BURN only, a lower BF% and greater VO_2PEAK were related to less time in ZONE5. BMI was unrelated to all workload measures. Laboratory-based maximal exercise testing does not adequately reflect the workload of simulated fire suppression and therefore may not be indicative of firefighter readiness to meet job demands. Less-fit firefighters rely on higher cardiovascular intensities to complete the same workload, and practitioners should consider this when selecting strategies to reduce job-associated cardiovascular risk.