Impact of anaerobic fitness on performance and physiology during simulated firefighting tasks
Authors: Bordonie Nicholas , Agostinelli Philip , Linder Braxton , Robbins Ann , Jones Parker , Reagan Lee , Mobley C Brooks 
Published: May 2024

BACKGROUND: Firefighting requires high levels of physical fitness and due to abnormal work schedules, on-duty training is necessary to meet occupational demands. However, firefighters are concerned with possible impairments in occupational readiness from various types of on-shift exercise. It has yet to be determined if higher levels of strength prove protective against potential decrements in readiness following on-shift exercise. Therefore, this study sought to determine if maximal strength influences occupational performance and physiological responses during simulated firefighting tasks (SFT) following different types of acute exercise. METHODS: 32 participants (17M/15F; 25.2 ± 4.1 yrs; 173.8 ± 9.8 cm; 75.6 ± 13.2 kg) completed 3-repetition max bench press (MBP), squat (MBS), deadlift (MDL), and vertical jump (VJ), and 3 experimental trials: resistance exercise (RE), aerobic exercise (AE), and rested control (CON) followed by the SFT (4 rounds of 10 deadlifts (using 85 or 135lbs) and a 0.15-mile carry with a 40lb-sandbag) in an environmental chamber (35°C; 50% humidity). Time to complete (TTC), rating of perceived exertion (RPE), and blood lactate concentrations (BLC) were analyzed. Participants were split into tertiles based on low, moderate, and high strength and power. Two-way ANOVAs were used to compare fitness level by exercise condition. RESULTS: There was a main effect of MDL on TTC (Low MDL: 1395 ± 248; Moderate MDL: 1135 ± 179; High MDL: 1007 ± 176; p < 0.01). Low DL participants had higher TTC compared to Moderate DL regardless of exercise type (ps < 0.02). Additionally, Moderate MDL participants had higher TTC compared to High MDL regardless of exercise type (ps < 0.01). There was a main effect of MBP on RPE (Low MBP: 14.7 ± 1.6; Moderate MBP: 13.7 ± 1.9; High MBP: 13.1 ± 1.6; p < 0.01). Participants with a High MBP had a lower RPE compared to Low MBP regardless of exercise type (ps < 0.01). There was a main effect of MBS on RPE (Low MBS: 14.7 ± 1.7; Moderate MBS: 13.5 ± 2.0; High MBS: 13.3 ± 1.5; p < 0.01). Participants with a Low MBS had higher RPE compared to Moderate and High MBS regardless of exercise type (ps < 0.02). There was a main effect of MDL on RPE (Low MDL: 14.3 ± 1.9; Moderate MDL: 14.2 ± 2.0; High MDL: 13.3 ± 1.6; p = 0.03). Participants with a High MDL had a lower RPE compared to Low MDL regardless of exercise type (ps = 0.03). There was an effect of MDL on BLC (Low MDL: 6.2 ± 3.2; Moderate MDL: 8.6 ± 3.0; High MDL: 8.8 ± 3.7; p < 0.01). Participants with a Low MDL had lower BLC compared to Moderate and High MDL participants regardless of exercise type (ps < 0.02). There was a main effect of VJ on BLC (Low VJ: 5.9 ± 2.7; Moderate VJ: 8.8 ± 2.9; High VJ: 8.9 ± 3.9; p < 0.01). Low VJ participants had lower BLC compared to Moderate and High VJ regardless of exercise type (ps < 0.02). All other interaction and main effects of TTC or physiological variables were not different based on fitness (ps > 0.15). CONCLUSIONS: These findings suggest performance and physiological responses during SFT differ based on anaerobic fitness (strength and power). Specifically, those with greater strength and power completed SFT faster, with lower perceived exertion and lactate accumulation. However, these differences in strength did not influence how participants responded after each type of exercise (RE, AE, CON). These findings emphasize the importance of strength training and provide support for using strength assessments to ensure occupational readiness. This project has no funding sources to disclose. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.