The Acute Effect of High-Intensity Resistance Training on Subsequent Firefighter Performance.

ABSTRACT: Mason, MR, Heebner, NR, Abt, JP, Bergstrom, HC, Shapiro, R, Langford, EL, and Abel, MG. The acute effect of high-intensity resistance training on subsequent firefighter performance. J Strength Cond Res 37(7): 1507-1514, 2023-High-intensity resistance training (HIRT) is commonly performed by structural firefighters on duty to enhance occupational readiness. However, exercise-induced fatigue may negatively impact subsequent occupational performance. Therefore, the purpose of this study was to assess the acute effect of HIRT on subsequent occupational physical ability in structural firefighters and to determine the time course of recovery. Seven resistance-trained male firefighters performed a timed maximal effort simulated fireground test (SFGT) in 3 randomized conditions: baseline (SFGT baseline ), 10 minutes post HIRT (SFGT 10min ), and 60 minutes post HIRT (SFGT 60min ). Work efficiency and air depletion were assessed during the SFGT. The timed HIRT session consisted of a standardized set of exercises using absolute training loads. Repeated measures analysis of variance and minimal difference (MD) analysis assessed group and individual effects between the conditions, respectively. The level of significance was set at p < 0.05. SFGT 10min completion time was greater than SFGT baseline (430 ± 137 vs. 297 ± 69 seconds, p < 0.01), with no difference between SFGT baseline and SFGT 60min (297 ± 69 vs. 326 ± 89 seconds, p = 0.08). The MD analysis indicated that all firefighters' SFGT 10min times exceeded the MD (±26.4 seconds) compared with SFGT baseline . However, 43% of firefighters still exceeded the MD at SFGT 60min . Air depletion during SFGT 10min was greater than that during SFGT baseline (2,786 ± 488 vs. 2,186 ± 276 lb·in -2 , p = 0.02), with no difference between SFGT baseline and SFGT 60min ( p = 0.25). Work efficiency during SFGT 10min was 40% lower than that during SFGT baseline ( p < 0.01), with no difference between SFGT baseline and SFGT 60min ( p = 0.25). These findings indicate that an acute bout of HIRT decreases multiple descriptors of firefighters' occupational performance 10 minutes post exercise with varied responses at 60 minutes post exercise.

Evaluation of Work Efficiency in Structural Firefighters.

ABSTRACT: Langford, EL, Bergstrom, HC, Lanham, S, Eastman, AQ, Best, S, Ma, X, Mason, MR, and Abel, MG. Evaluation of work efficiency in structural firefighters. J Strength Cond Res 37(12): 2457-2466, 2023-To perform occupational tasks safely and effectively, firefighters (FF) must work quickly and consume air provided by the self-contained breathing apparatus (SCBA) efficiently. However, most literature only factors work rate into performance, neglecting the inherent time limitation imposed by the SCBA. The purpose of this article was to (a) evaluate the reliability and variability in a "work efficiency" (WE) performance metric reflective of both work rate and air consumption; (b) explore the relationship between WE and established measures of metabolic strain; and (c) identify fitness, anthropometric, and demographic correlates of WE. About 79 structural FF completed an air consumption drill while breathing through an SCBA. Self-paced work duration and air consumption were entered into the WE equation. A subsample of FF (n = 44) completed another randomized trial while breathing through a portable gas analyzer. Anthropometric and fitness data were collected separately. Correlations were performed between WE vs. fitness, anthropometric, demographic, and metabolic outcomes. Multiple linear regression was used to identify the strongest predictors of WE. WE was reliable (intraclass correlation coefficient = 0.71) and yielded inter-FF variability {0.79 ± 0.25 ([lb·in-2·min]-1) × 104; coefficient of variation = 31.6%}. WE was positively correlated to oxygen consumption (V̇O2) (L·minute-1, mL·kg-1·minute-1) and tidal volume and negatively correlated to V̇E/V̇O2 and respiratory frequency. Height, upper-body endurance, and aerobic endurance were identified as the strongest predictors of WE (adjusted R2 = 0.59, RMSE = 0.16). WE is a reliable and occupationally relevant method to assess FF performance because it accounts for work rate and air consumption. Firefighters may enhance WE through a training intervention focused on improving metabolic tolerance, upper-body endurance, and aerobic endurance.

Cardiovascular and metabolic responses of active sitting while performing work-related tasks.

Stability balls and active-balance sitting chairs have recently emerged as a way to reduce sedentary behaviours in office settings. The purpose of this study was to determine differences in caloric expenditure and heart rate between a standard chair (SC), stability ball (SB) and active balanced sitting chair (ST) while performing work-related tasks. Participants (n = 20) performed a 10-minute randomised reading and typing task while sitting on the SC, SB and ST. For both the reading and typing tasks, heart rate (HR), caloric expenditure per minute and metabolic equivalents were all significantly greater (i.e. 6-13%; 19-40%; 18-39%, respectively) while using the ST when compared to the SC and SB. No significant differences were observed between the SB and SC for any of the comparisons. The ST produced a greater HR response and caloric expenditure than the SC or SB, indicating that active balanced sitting may be a feasible way to increase energy expenditure in an office setting. Practitioner summary: The purpose of this study was to determine differences in cardiovascular and metabolic responses to various forms of office chairs. The key finding was that active sitting on a balance chair significantly increased heart rate and caloric expenditure as compared to a stability ball and standard chair. Abbreviations: SC: standard chair; SB: stability ball; ST: active balanced chair; HR: heart rate; kcalmin: caloric expenditure per minute; MET: metabolic equivalents.

Firefighter Health: A Narrative Review of Occupational Threats and Countermeasures.

Structural firefighters are responsible for protecting properties and saving lives during emergency operations. Despite efforts to prepare firefighters for these hazardous occupational demands, the unfortunate reality is that the incidence of health morbidities is increasing within the fire service. Specifically, cardiovascular disease, cancer, and mental health disorders are among the most documented morbidities in firefighters. Pubmed and Google Scholar search engines were used to identify peer-reviewed English language manuscripts that evaluated firefighters' occupational health threats, allostatic factors associated with their occurrence, and evidence-based strategies to mitigate their impact. This narrative review provides fire departments, practitioners, and researchers with evidence-based practices to enhance firefighters' health.

Etiology of Exercise Injuries in Firefighters: A Healthcare Practitioners' Perspective.

The purpose of this study was to query healthcare practitioners (HCPs) who treat firefighter injuries to identify risk factors and mechanisms associated with musculoskeletal injuries during exercise. A phenomenological design was utilized to understand the experiences of HCPs while treating firefighters' musculoskeletal injuries due to exercise. Semi-structured interviews were conducted with 14 HCPs. Two interviews were pilot-tested with HCPs to ensure reliability and validity. Interviews were transcribed and uploaded to a qualitative analysis software program. Although the study inquired about injuries incurred by any exercise modality (e.g., endurance and resistance training), injuries induced during resistance training were prominent among HCPs as resistance training emerged as a primary exercise injury mechanism. HCPs indicated that the back and shoulder were prevalent anatomical exercise injury locations. Risk factors for exercise injuries included age, immobility, movement proficiency, and factors associated with fatigue. Exercise injury mechanisms included poor resistance training technique and overexertion. These findings could guide exercise program design, use of movement assessments, and the identification of other countermeasures to decrease the risk of resistance training exercise injuries among firefighters.

The Impact of Gloves and Occupational Tasks on Handgrip Strength in Structural Firefighters.

Adequate handgrip strength (HGS) is important to safely perform fireground tasks. However, there is limited research describing the deleterious impact of glove use and fatigue from occupational tasks on HGS. Therefore, the aims of this investigation were to quantify the impact of glove use and occupational tasks on HGS, to explore the relationship between HGS versus the glove and task-induced decrement in HGS, and to evaluate the relationship between HGS and decrement in HGS versus occupational performance. Fourteen (Male: n = 13) career structural firefighters (Age: 35.5 ± 7.2 yr) performed a maximal isometric HGS assessment with and without gloves before and immediately following completion of a simulated fireground test (SFGT). General linear model with written contrast was used to identify significant differences in HGS between conditions. Pearson Correlations were used to describe bivariate relationships between the decrements in HGS and occupational task times. Significance was set at p < 0.05. There were significant main effects indicating that gloves, performing occupational tasks, and their combined effects decreased HGS (p < 0.001 for all). There were strong inverse relationships between baseline (barehanded) HGS versus the decrement in HGS from donning gloves (r = -0.82, p < 0.001) and from performing occupational tasks with gloves (r = -0.61, p = 0.021). Baseline HGS and the decrement in HGS due to wearing gloves and performing occupational tasks were not correlated to the timed completion of occupational tasks (p ≥ 0.27). These findings suggest that the use of regulation fire gloves and work-induced fatigue reduces HGS and these decrements are related to HGS. Practitioners are encouraged to utilize training strategies to optimize HGS among structural firefighters.

Effects of Active Sitting on Reading and Typing Task Productivity.

Increased sedentary behavior and reduced physical activity among children and adults has led to the advent of various active devices to combat these behaviors. Active sitting, consisting of modified chairs or stability balls, allows the body to stay dynamic while seated. While research has evaluated the health benefits of active sitting, minimal research has shown the effects of active sitting on productivity in adult populations. The purpose was to evaluate the effects of various chairs (active versus non-active) on typing and reading task productivity. Twenty adult participants performed typing and reading tasks for 10-minutes while sitting on each of the following: standard chair (SC), stability ball (SB), and active sitting chair (ST). Reading comprehension (RC), words per minute (WPM), accuracy, and errors were measured following each task. Additionally, perceived productivity was measured using a self-reported rating of difficulty scale (1-10). In terms of RC, there was no difference between the chairs (p = 0.16). However, perceived productivity was significantly greater on the SC as compared to SB (p < 0.01) and ST (p < 0.01). For the typing task, no differences were demonstrated for errors (p = 0.87) or accuracy (p = 0.91). However, WPM was significantly greater on SC (38.8 ± 10.5) compared to ST (35.9 ± 9.5) (p = 0.02). For perceived typing productivity, SC and SB demonstrated significantly greater values compared to ST (p < 0.01). Results suggest that various types of active sitting may have a minimal negative effect on workplace performance and perceived productivity.