Author ORCID Identifier

https://orcid.org/0000-0003-0846-7046

Date Available

2-5-2022

Year of Publication

2021

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Education

Department/School/Program

Kinesiology and Health Promotion

Advisor

Dr. Mark Abel

Abstract

High intensity resistance training (HIRT) is commonly performed by structural firefighters to enhance preparedness for occupational demands. Despite the potential for HIRT to induce beneficial adaptations over time, it is important to determine if a single on-duty HIRT session is detrimental to subsequent occupational physical ability due to exercise-induced fatigue. Therefore, the primary purpose of this study was to assess the acute effect of HIRT on occupational physical ability in structural firefighters and to determine the time course of recovery. The secondary purpose was to determine if timed completion of a standardized bout of HIRT was correlated to occupational performance in a non-fatigued state, as this may allow the fire service to utilize exercise performance to predict readiness to successfully perform occupational tasks.

The occupational physical ability of seven male resistance trained career firefighters (Age: 35.8 ± 4 yr; Height: 181.6 ± 6 cm; Body mass: 90.6 ± 8 kg) was evaluated based on timed completion of a maximal effort simulated fireground test (SFGT). The SFGT consisted of seven standardized tasks (stair climb, hoseline advance, equipment carry, ladder raise, forcible entry, victim search, and rescue) which were performed in personal protective equipment (PPE) and using a self-contained breathing apparatus (SCBA). Work efficiency (1 / (Air depletion x SFGT completion time)) x104), air depletion, heart rate, blood lactate, rating of perceived exertion (RPE), and thermal sensation were assessed before, during, and after the SFGT. The timed HIRT session consisted of a standardized set of exercises and absolute training loads. Firefighters performed the SFGT in three randomized conditions, separated by at least 48 hours: baseline (SFGTbaseline), 10 min post-HIRT (SFGT10min), and 60 min post-HIRT (SFGT60min). For the primary aim, repeated measures ANOVA were used to identify main effects for condition in SFGT completion time, work efficiency, air depletion, heart rate, blood lactate, RPE, and thermal sensation. Individual differences in SFGT time were assessed using Intraclass Correlation Coefficient2,1 and minimal difference (MD) scores calculated from a SFGT familiarization trial and SFGTbaseline. For the secondary aim, Pearson Product Moment correlation analysis was used to identify the relationship between HIRT time (mean value of 2 HIRT sessions) versus SFGTbaseline time.

Aim 1: There was no difference in HIRT completion time between SFGT10min and SFGT60min conditions (p = 0.41) indicating an equivalent exercise stimulus was applied in both exercise conditions. SFGT10min completion time was greater than SFGTbaseline (430 ± 137 vs. 297 ± 69 s, p = 0.008), with no difference between SFGTbaseline and SFGT60min conditions (297 ± 69 vs. 326 ± 89 s, p = 0.080). The MD analysis for SFGT time indicated that all firefighters’ SFGT10min times exceeded the MD (± 26.4 s), indicating that a real difference existed between conditions. Whereas, 43% (3 of 7) of firefighters still exceeded the MD at SFGT60min. Air depletion during SFGT10min was greater than SFGTbaseline (2786 ± 488 vs. 2186 ± 276 lb·in-2, p = 0.020), with no difference between SFGTbaseline and SFGT60min (p = 0.253). Work efficiency during SFGT10min was less than SFGTbaseline ((0.59 ± 0.32 vs. 0.99 ± 0.29 ((lb·in-2·min)-1)104, p < 0.001)), with no difference between SFGTbaseline and SFGT60min (p = 0.247). SFGT10min pretest RPE (p < 0.001), pretest thermal sensation (p < 0.001), pretest blood lactate (p < 0.001) and post-test thermal sensation (p = 0.004) were greater than SFGTbaseline.

Aim 2: Bivariate correlation analysis revealed that there was no correlation between average time to complete the HIRT session versus time to complete the SFGTbaseline condition (r = -0.164, p = 0.73).

These findings indicate that an acute bout of HIRT decreases firefighters’ occupational performance 10 min post-exercise with varied responses at 60 min post-exercise. Performing on-duty exercise is recommended by the National Fire Protection Association and is important to enhance chronic occupational readiness. However, firefighters and tactical strength and conditioning practitioners should be aware of the acute deleterious effects associated with performing HIRT on-duty. Factors that may influence the decision to use HIRT on-duty may include firefighters’ fitness level, acclimation to HIRT, the magnitude of HIRT loading parameters, and performing HIRT during low volume call times or just prior to the end of a shift.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2021.296

Funding Information

This study was supported by the Arvle and Ellen Turner Thacker Research Fund in 2018.

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