The Effect of a Novel Tactical Training Program on Physical Fitness and Occupational Performance in Firefighters

Abstract

Pawlak, R, Clasey, JL, Palmer, T, Symons, TB, and Abel, MG. The effect of a novel tactical training program on physical fitness and occupational performance in firefighters. J Strength Cond Res 29(3): 578–588, 2015—Structural firefighting is a dangerous and physically demanding profession. Thus, it is critical that firefighters exercise regularly to maintain optimal physical fitness levels. However, little is known about optimal training methods for firefighters, and exercise equipment is often not available to on-duty firefighters. Therefore, the purpose of this study was to determine the effect of a novel supervised on-duty physical training program on the physical fitness and occupational performance of structural firefighters. Twenty professional male firefighters were divided into a supervised exercise group (SEG; n = 11) and a control group (CG; n = 9). The SEG participated in a 12-week circuit training intervention. The SEG exercised for 1 hour on 2 d·wk⁻¹. At baseline and after the intervention, subjects performed a battery of physical fitness tests and a simulated fire ground test (SFGT). At baseline, there were no significant differences (p = 0.822) in the completion rate of the SFGT in the SEG (82%) vs. the CG (78%). After the intervention, a significantly greater proportion of the firefighters in the SEG completed the SFGT compared with the CG (SEG = 100% vs. CG = 56%; p < 0.013). In addition, the SEG demonstrated significant improvements in body mass, fat mass, and body mass index (p ≤ 0.05). The findings of this study indicate that training with firefighter equipment improved occupational performance and anthropometric outcomes in incumbent firefighters. Furthermore, implementing a supervised exercise program using firefighter equipment can be done so in a safe and feasible manner.

Introduction

Firefighting is a dangerous and physically demanding profession that requires regular exercise training to ensure optimal levels of occupational performance. The National Fire Protection Association (²¹) has recognized the importance of exercise training for firefighters and has suggested that firefighters participate in exercise programs while on-duty (^20,21). Previous investigations have reported that exercise programs that use traditional exercise equipment have been successful at improving physical fitness and occupational physical ability in firefighters (^23,27). However, many fire stations are often not equipped with traditional fitness equipment for firefighters to train with while on-duty. In an effort to overcome this barrier, it seems reasonable that task-specific exercises may be included in an exercise program by using firefighting equipment rather than traditional fitness equipment. To date, there is no research to support the efficacy of using firefighter equipment to improve occupational physical ability.

Fire ground tasks challenge cardiovascular and muscular fitness capabilities (^12,15). Thus, it is important that firefighters use training methods that effectively target cardiovascular fitness and muscular strength and endurance outcomes (^4,6,9). Circuit training is 1 mode of exercise that has been shown to produce similar physiological demands compared with performing fire ground suppression tasks (¹). Specifically, Abel et al. (¹) demonstrated that a bout of circuit training produced similar heart rate and blood lactate responses compared with smoke diving and some fire suppression tasks. However, there is no longitudinal research to support the use of circuit training to improve fitness and occupational performance in firefighters.

Finally, another factor that may enhance the efficacy of exercise programs for firefighters is exercise supervision. Research conducted in other populations suggests that supervision can improve performance and health outcomes by enhancing motivation, and assisting with goal setting and exercise prescription (^3,5,11,18). Given that some fire departments are paying for incumbent firefighters to become certified trainers (e.g., Peer Fitness Trainer) or are employing strength and conditioning professionals to conduct department wide fitness programs, it is important to evaluate the effect that supervision has on firefighter performance and fitness outcomes. Therefore, the purpose of this study was to determine the effect of a novel supervised circuit training program on the physical fitness and occupational performance of firefighters. The exercise program primarily used common firefighter equipment found in a fire station, including hoses, ladders, self-contained breathing apparatuses, and foam buckets. It was hypothesized that implementing a novel physical training program would enhance overall firefighter cardiovascular fitness, muscular strength, body composition, and performance on simulated firefighting job tasks compared with a control group (CG).

Methods

Experimental Approach to the Problem

Professional firefighters were recruited to participate in a study to determine the effects of a novel exercise program on the physical fitness and occupational physical ability of firefighters. This study used a convenience sample of male incumbent firefighters that were stratified into either a supervised exercise group (SEG) or an unguided CG based on work schedule and station assignment. The independent variable in this study was the circuit training intervention, and the dependent variables included assessments of physical fitness and occupational physical ability. Select physical fitness outcomes were assessed because they have been found to be associated with the task-specific performance of firefighters (²⁶). Relative changes in these fitness outcomes allows for comparisons to published training programs that have used traditional exercise equipment (^23,27). Occupational physical ability was assessed using a simulated fire ground test (SFGT). The SFGT was performed once by all subjects for familiarization purposes, and again at baseline and posttest assessments.

Subjects

A convenience sample of 20 healthy male professional structural firefighters (ages 23–49) were recruited to participate in this study (age: SEG = 35.0 ± 6.6 years; CG = 42.3 ± 5.6 years, p = 0.014; firefighting experience: SEG = 10.8 ± 6.0 years; CG = 20.7 ± 8.6 years, p = 0.011). The subjects were recruited from a fire department located in a metropolitan area that services about 37,000 people in the midwestern United States. To be eligible for this study, the subjects were “cleared for duty” after a physical examination by a physician. All participants provided written informed consent before participation in the study. A detailed explanation was provided to the participants regarding the aims, benefits, and risks associated with the investigation. Participants were informed that their participation in this study would not affect their employment status. The procedures used in this study were approved by the University's Institutional Review Board.

Procedures

Standing height was measured (to the nearest 0.1 cm) without shoes using a portable stadiometer (Road Rod 214; Seca, Hanover, MD, USA). Body mass was measured (to the nearest 0.1 kg) in lightweight clothing without shoes using a digital scale (TBF-521; Tanita Corporation, Arlington Heights, IL, USA). Waist circumference was measured (to the nearest 0.1 cm) at the narrowest part of the torso above the umbilicus and below the xiphoid process (²) using an anthropometric tape (Medco, Chicago, IL, USA). Two measurements were taken, and the average of these values was used for data analysis. If the 2 measurements were not within 1 cm, a third measurement was taken. Percent fat was assessed through whole-body bioelectrical impedance analysis (BIA; Model: 310; Biodynamics Corporation, Seattle, WA, USA). Specifically, electrodes were placed on the subjects' wrist and hand, and ankle and foot while lying in the supine position on a nonconductive surface. Age, sex, height, and body mass were entered into the BIA unit to estimate percent fat using the manufacturer's proprietary prediction equation.

Fitness Assessments

All fitness tests were overseen by a National Strength and Conditioning Association (NSCA)-certified strength and conditioning specialist. The tests were explained and demonstrated to all subjects to ensure uniform procedures. The tests were sequenced to minimize the effects of residual fatigue on subsequent tests. Fitness assessments tests were chosen based on their relevance to performing firefighting tests as reported in the literature (^26,29).

Peak Oxygen Consumption—Aerobic Fitness

The Gerkin submaximal treadmill protocol was used to determine peak oxygen consumption with a validated, population-specific (R² = 0.328; standard error of estimate = 5.20 ml·kg⁻¹·min⁻¹) prediction equation

(ml·kg⁻¹·min⁻¹) = 56.981 + 1.242 (time to 85% HRmax [min] − [0.805 × BMI]); (³⁰). This submaximal protocol has been previously evaluated and shown that there were no significant differences between measured and predicted

in firefighters (²²). Subjects began the protocol by walking on the treadmill at 80.4 m·min⁻¹ for 3 minutes. The treadmill velocity or grade was increased each minute until the participant's heart rate reached 85% of age-predicted maximum. The age-predicted maximum heart rate was calculated using an equation specific to the

protocol (HRmax: 208 − [0.7 × age]). Upon completion of the test, each participant continued to walk on the treadmill at a desirable speed to ensure proper recovery.

Hand-Grip Strength

Hand-grip strength was measured in each hand as a general indicator of upper-body strength and was measured because it has been found to be associated with firefighter performance (²⁶). The test-retest reliability of the hand-grip assessments in this sample were r = 0.958 and 0.975 in the right and left hands, respectively. Hand-grip strength was evaluated with a hand-grip dynamometer (Model 78010; LaFayette Instrument Company, Lafayette, IN, USA). Specifically, each participant flexed the elbow to 90° and maximally squeezed the dynamometer. Each trial was recorded (to the nearest 1 kg), and the average of the 3 trials was used to determine hand-grip strength for each hand.

Flexibility

Lower back and hamstring flexibility was measured (to the nearest 1.0 cm) without shoes using a sit and reach box with the foot plate set at 23 cm (Acuflex I; Novel Products, Inc., Rockton, IL, USA) (²). The test-retest reliability of the sit and reach assessment in this sample was r = 0.964. From a seated position with legs straight, participants were instructed to overlap their hands, reach caudally as far forward as possible, and hold the position for approximately 2 seconds. Three measurements were taken (to the nearest centimeter), and the average of the best 2 trials was used for data analysis.

Simulated Fire Ground Test

An SFGT was administered to simulate and assess the occupational physical ability of 6 standardized fire ground tasks. These tasks were selected based on their occurrence on the fire ground and from the opinion of an expert informant (i.e., firefighter). Each task was accomplished, in succession, as quickly as possible with maximal effort. The duration of each task and the overall test time were measured with a hand-held stop watch (Sportline, Yonkers, NY, USA) and recorded to the nearest hundredth of a second. The subjects had experience performing these simulated fire ground tasks in training operations, albeit not timed. Therefore, a familiarization trial was provided to each subject to allow for recognizing the time variable associated with the test. To ascertain the validity of the SFGT, the subjects completed a brief questionnaire (composed of a 5-point likert-type scale) to rate how relevant they perceived the overall fireground test compared with performing tasks on the fire ground (1 = “Not relevant,” 3 = “Relevant,” 5 = “Very Relevant”). The median response for the overall relevancy of the SFGT was 5 (range, 3–5) indicating that the subjects felt the SFGT was a very relevant representation of actual fire ground tasks.

The SFGT was composed of the following tasks: tower climb, equipment hoist, forcible entry simulation, ladder raise, hose advance, and victim rescue. Each task was completed while wearing full protective fire gear and with a self-contained breathing apparatus (SCBA, Survivair, Honeywell Safety Products). Although the firefighters were familiar with each SFGT task, as these tasks are a part of standard trainings evolutions within the fire department, we felt it was important to provide a standardized review of each tasks. Therefore, each task was explained and demonstrated before initiating the testing process. Furthermore, for familiarization purposes, each participant performed the SFGT 1 time before the baseline assessment. To compare the consistency for familiarization and baseline SFGT times, a paired sample t-test was conducted in 15 subjects. This analysis revealed a significant decrease in SFGT time from familiarization to baseline (228.9 ± 38.1 seconds vs. 212.2 ± 35.9 seconds, p < 0.001), demonstrating a familiarization effect. The test-retest reliability of the SFGT in this subsample was r = 0.81.

Tower Climb

Each participant began the SFGT by lifting and carrying a 22-kg hose pack up a 5 story tower. The hose pack was placed on either shoulder. The task's time started on the command of the testing proctor, and the split time was taken (to the nearest 0.1 seconds) when the subject reached the fifth story and placed the hose on the ground.

Hose Hoist

The subject covered 4.6 m to the edge of a platform at the top of the tower and hoisted a 22-kg hose roll that was secured to a rope. The hose roll was hoisted up 5 stories. The task's split time was initiated at the termination of the stair climb task and completed when the hose roll was placed on the platform.

Forcible Entry Simulation

The firefighter then descended the 5 story tower and covered 4.6 m to perform a forcible entry simulation task. The firefighter drove a 75-kg metal I-beam a distance of 1.5 m using a 3.64-kg mallet. The task's split time was initiated at the termination of the equipment hoist task and was completed when the I-beam was driven the required 1.5 m.

Ladder Raise

The firefighter covered 6.1 m to perform a ladder raise task. The firefighter raised an 8-m extension ladder to a second story window using a hand over hand technique, touching each rung. The task's split time was initiated at the termination of the forcible entry task and completed when the firefighter placed the ladder at an appropriate climbing angle of approximately 75°.

Hose Advance

The firefighter covered 3.7 m to advance a charged 1¾ inch hose-line. The hose-line was laid out in the shape of a “U” to standardize the resistance for each subject. The firefighter placed the hose-line over the shoulder and advanced the hose-line 22.9 m. The task's split time was initiated at the termination of the ladder raise task and completed when the firefighter's feet crossed the task finish line.

Victim Rescue

The firefighter covered 5.2 m, lifted and dragged an 80-kg mannequin 30 m while walking backward. The tasks split time and the overall SFGT time were taken when the mannequin's feet crossed the finish line.

Heart Rate Measurement

Heart rate was assessed during the SFGT with a heart rate monitor (Polar A1 Electro Oy; Kempele, Finland) that was placed around the subject's chest. A heart rate recording device (ActiTrainer; Fort Walton Beach, FL, USA) was secured to the participant's upper arm in a neoprene sleeve and was used to record the heart rate per 15-second sampling period. Each set of 15-second heart rates was multiplied by 4 to express heart rate per minute. The recording device was downloaded to a personal computer after the testing session using the manufacturer's software (ActiLife). The mean absolute and relative heart rate values during the SFGT were used for data analysis. Relative heart rate was calculated by dividing the average absolute heart rate during the SFGT by the age-predicted maximum heart rate (i.e., 220-age [yrs]) and multiplying the quotient by 100. In addition, rating of perceived exertion (RPE) was assessed after the SFGT using a 6–20 category-ratio scale (⁷) to determine the perception of effort during the SFGT.

Training Intervention

The SEG participated in a 12-week training intervention. This group trained 2–3 d·wk⁻¹ (i.e., total 28 exercise sessions), while on duty, for approximately 1 hour per exercise session. Training frequency was chosen to accommodate the on-duty work schedule for the firefighters involved in the study. The exercise program was supervised and led by the principal investigator, who is a firefighter within this fire department with nearly 17 years of experience, and is an NSCA-certified strength and conditioning specialist. The roles of the SEG leader were to instruct, supervise, and motivate subjects during the exercise sessions.

The exercise program incorporated a general warm-up, dynamic stretching, circuit training strength and endurance exercises, cardiovascular exercise, and static flexibility training. Circuit training was used as the primary training mode for the training intervention. For the SEG, signs were posted at each “exercise station” to identify the exercises to be performed and the order that the exercises were to be performed in. Each subject was given a demonstration of each exercise to ensure correct form and prevent potential injury. In general, the exercise program consisted of performing about 10–15 repetitions per exercise with a recovery period of 30 seconds (work:rest ratio: 1:1). A summary of the exercise program's periodization scheme is provided in Table 1. Variations to each exercise were provided to subjects to account for potential differences in the subjects' fitness levels and to provide progressive challenges as fitness levels improved throughout the training intervention. For instance, variations included adding an SCBA for additional resistance using a ladder of a different weight, etc. The work-to-rest ratio was modified as well (e.g., decrease in recovery period: 30 seconds to 15 seconds to 0 seconds at the end of the intervention period) to account for improvements in fitness levels. In addition, cardiovascular conditioning was periodized in a linear manner so that progressive improvements would be made during the training period. The exercises incorporated in the training intervention focused on the major muscles of the chest, back, legs, shoulders, and torso. Body weight exercises (e.g., push-ups, sit-ups, body squats, and lunges) were used at the outset of the intervention with gradual introduction of fire equipment to induce physiological adaptations. Cardiovascular training consisted of 20 minutes of either laps around the fire house, running on a treadmill, shuttle runs, 20-yard sprints, or utilization of an elliptical machine. Physiological adaptations were accounted for by increasing speed on the respective piece of equipment or decreasing rest time between work intervals/repetitions.

Table 1: Summary of firefighter training program.^*

Subjects in the SEG were not discouraged to exercise off-duty but were instructed to not exceed the exercise habits they had before participating in the study. Subjects' attendance at the exercise sessions were recorded by the principal investigator. Subjects from the SEG were excluded from data analysis if they were absent for more than 20% of the exercise sessions. One subject did not meet the requirements and thus was excluded from all statistical analysis. The CG participated in the familiarization, baseline, and posttest components of this study only. This group was asked to maintain their current physical activity levels throughout the duration of the study.

Statistical Analyses

Basic statistics (mean ± SD) were used to describe demographic and outcome variables. Comparisons of baseline vs. posttest outcome measures within and between groups were made using mixed factor analyses of variance. Paired and independent samples t-tests were used in post hoc analyses to determine where differences existed. There were no differences between groups at baseline (p > 0.05).

Two-way (2 × 2) contingency table analyses using Pearson's χ² tests were conducted to evaluate whether the proportion of firefighters who successfully completed the SFGT was different between the intervention and CGs at baseline and posttest. Effect sizes for the Pearson's χ² were calculated using the Cramer's V statistic. The values of 0.10, 0.30, and 0.50 represent small, medium, and large effect sizes, respectively (¹⁷). Given the small number of firefighters in the CG that completed the SFGT at posttest, paired t-tests were used to evaluate within-group differences from baseline to posttest (within both groups). Difference scores (posttest time − pretest time) for posttest vs. baseline times were calculated on the overall SFGT and for each task for firefighters who completed the baseline and posttests in each group. Independent t-tests were used to compare difference scores between groups. If a subject could not complete a task, the SFGT was terminated and consequently the subject did not receive a time for the SFGT.

The normality of variable distributions were assessed using Fisher's Skewness coefficient (coefficient = skewness/standard error of skewness). The distribution was considered to be skewed if the coefficient was greater than the absolute value of 1.96. Eighty-eight percent of the descriptive statistics were normally distributed. Of the distributions assessed,

was negatively skewed at baseline in the SEG and CG groups (Fisher's coefficient of skewness: −1.96 and −2.43, respectively). Baseline body mass was positively skewed in the CG (Fisher's coefficient of skewness: 2.23). The

and body mass distributions in the CG were skewed because of a single outlier. To evaluate the effect of this outlier, the subject's data were removed, and the variables were reanalyzed. This analysis resulted in a similar statistical outcome, and the subject's data were retained in the original analysis. Paired t-tests were used to compare the RPE within the SEG and CG from baseline to posttest. The test-retest reliability of various fitness assessments and the SFGT was evaluated using Cronbach's Alpha. The level of significance was set at p ≤ 0.05 for all statistical analyses.

Results

Descriptive statistics for SFGT in the SEG and CG are presented in Table 2. At baseline, there was no significant difference between groups in the SFGT completion rate, as 82% (9/11 subjects) of the SEG and 78% (7/9 subjects) of the CG successfully completed the SFGT (Pearson's χ² (1, 20) = 0.05, p = 0.822, Cramer's V = 0.05). At posttest, a significantly greater proportion of subjects in the SEG successfully completed the SFGT (100%, 11/11 subjects) compared with the CG (56%, 5/9 subjects; Pearson's χ² (1, 20) = 6.11, p = 0.013, Cramer's V = 0.55).

Table 2: Simulated fire ground test task times and heart rate data for subjects who completed the test at baseline and posttest in the supervised exercise and control groups.^*†

Among the subjects who successfully completed baseline and posttest SFGTs, in the SEG, there were no differences in SFGT task times, whereas the CG significantly increased time to complete the equipment hoist, forcible entry, ladder raise, and victim rescue tasks (p ≤ 0.043; Table 2). In addition, among subjects who successfully completed baseline and posttest SFGTs, the between-group comparisons of change scores indicated significant and favorable outcomes for the SEG on the overall SFGT time and for the stair climb, ladder raise, and victim rescue tasks (p ≤ 0.031; Table 2). On average, the SEG group decreased time to completion on 4 of 6 tasks (mean percent change on 4 tasks = −7.5%), whereas the CG demonstrated an increased trend in time to complete all 6 tasks (mean percent change on 6 tasks = 16.2%; Table 2). After the intervention, 67% (6 of 9) of subjects in the SEG decreased SFGT time, whereas 100% (5 of 5) of subjects in the CG increased SFGT time (Figure 1). At baseline, 1 subject in the SEG failed on the hose hoist, whereas all other subjects (in both groups) failed on the victim rescue. RPE was measured for the subjects that completed the SFGT at baseline and posttest. The mean RPE decreased from baseline to posttest in the SEG (19.9 and 18.5, respectively; p = 0.01) with no change in the CG (18.0 and 18.4, respectively; p = 0.69).

Figure 1: Individual firefighters' completion time on the simulated fire ground test at baseline and posttest in the supervised exercise group (n = 9) (A); and the control group (n = 5) (B). *Dotted line represents the group mean completion time. Data only represents subjects who completed baseline and posttest simulated fire ground tests.

Changes in physical fitness outcomes are displayed in Table 3. There were no significant differences in physical fitness and anthropometric outcomes between groups at baseline (p ≤ 0.152). Regarding changes in physical fitness outcomes, there were significant interaction effects for body mass, fat mass, and BMI. Specifically, during the intervention, the SEG significantly decreased body mass, fat mass, and BMI compared with the CG (p ≤ 0.044). In addition, there were significant interaction effects for resting heart rate (p ≤ 0.014) and relative

(p ≤ 0.006). However, changes in body mass may affect relative

and resting heart rate, independent of changes in cardiorespiratory function (¹³). Therefore, absolute

and resting heart rate (scaled for body mass) were evaluated. Expressing cardiorespiratory function independent of body mass indicated that there were no significant interaction effects of the exercise program on absolute

(p ≤ 0.169) or scaled resting heart rate (p ≤ 0.096). Furthermore, there were no significant changes in percent body fat or flexibility. No injuries were reported while conducting the training intervention.

Table 3: Descriptive data for the supervised exercise and control groups at baseline and posttest.^*†

Discussion

The purpose of this study was to determine whether a novel physical training program would improve the occupational physical ability and physical fitness of firefighters. The findings from this study indicated that the SEG improved the completion rate on a standardized SFGT from 82 to 100% after the intervention, whereas the CG declined from 78 to 56%. Furthermore, among firefighters who completed baseline and posttest SFGTs, the SEG demonstrated a slight improvement (−1.5%) in the SFGT, whereas the CG decreased performance by 20.2% (Table 2). It is important to note that the −1.5% improvement in the SFGT time is an underestimate of the SEG performance. That is, 2 additional firefighters in the SEG were not able to complete the SFGT at baseline but were able to complete the SFGT after the intervention, thus, they were not accounted for in this calculation and may have contributed to the relative improvement in the SEG. Furthermore, the mean RPE reported for the SFGT significantly decreased in the SEG after the intervention, without a concurrent change in the CG. This would suggest that the physiological adaptations developed from this novel training intervention made performance of fire ground tasks feel less difficult. Taken collectively, the general findings from this study indicate that this practical training program improved firefighter work efficiency and decreased the perceived work effort on an SFGT (⁷).

There are several potential factors that may have contributed to the improved SFGT completion rate in the SEG compared with the CG, including program supervision and design. The SEG was supervised and led by a qualified strength and conditioning professional who has 17 years of firefighting experience and 2 years of experience as an NSCA-certified strength and conditioning specialist. Research conducted on other populations has demonstrated that supervision of training programs can improve performance and health outcomes (^3,5,11,18). These studies have indicated that supervision provided by a qualified professional enhances the likelihood of positive training outcomes by maintaining attendance records, motivating subjects, assisting in goal setting, and prescribing exercise and training loads (^3,18). Although we did not compare injury outcomes between groups in this study, it is promising that the SEG did not incur any injuries. This may be due to the supervision of a qualified fitness professional.

In this study, daily attendance in the exercise program was kept by the principal investigator, and subjects in the SEG were encouraged to attend the training sessions regularly to maximize the effects of the program. The average attendance rate for the SEG was 24 of 28 sessions (86%), which provided a significant dose of the training program and thus yielded improved physical performance for most firefighters. Although participation in this study was voluntary, these attendance records may have held the SEG accountable for their participation. Coutts et al. (¹¹) support the notion that supervision leads to greater exercise adherence. In their study, the supervised group completed more training sessions, which was likely the catalyst for improvements in performance outcomes.

The exercise program supervisor in this study also provided motivation and encouragement to the SEG. Many individuals are unable to self-motivate and thus fail when attempting to obtain established goals (²⁸). In support of this point, Mazzetti et al. (¹⁸) conducted a supervised 12-week study on moderate to highly trained subjects. The authors concluded that direct supervision from a qualified professional may improve performance by providing motivation from verbal support, enhancing the competitiveness of the subjects (i.e., performing for an audience), and directing the progression of training loads in an appropriate manner.

The design of the training program also may have contributed to the improved SFGT completion rate in the SEG. The training program was composed of a (a) linear periodized, (b) circuit training program that (c) primarily used equipment found at a fire station to provide external resistance. To date, there is limited research evaluating the effects of linear periodized training programs on firefighter performance. Peterson et al. (²³) conducted a 9-week supervised training program that compared a traditional linear periodized program with an undulating program in firefighter recruits. The researchers reported that the linear and undulating training groups improved firefighter physical ability by 21 and 29%, respectively. In contrast, this study demonstrated a more modest improvement (1.5%) in firefighter physical ability using a linear periodized training program. The discrepancies between these studies may be due to several factors including differences in periodization strategy, training intensity, and training volume. A description of these factors is provided below.

Peterson et al. (²³) evaluated 2 distinct periodization strategies that targeted specific training outcomes (e.g., muscle endurance, strength, and power) by microcycle (linear periodization group) or within a single exercise session (undulating periodization group), whereas this study only used a linear periodized program. Although both studies used a linear periodization program, this study designed a circuit training program in a linear manner. Thus, inherent differences in training intensity and volume between a circuit-based program vs. a traditional linear program may contribute to the differences. Furthermore, there are several studies that support the superior findings of the undulating periodized program reported by Peterson et al. (²³). These training studies suggest that undulating (i.e., nonlinear) training programs may be a better alternative to linear periodization programs for enhancing fitness parameters. (^19,25). The training intensities used by firefighter recruits in the Peterson et al. (²³) study were likely substantially greater than those used in this study. For instance, Peterson et al. (²³) used resistance training equipment, whereas this study used the firefighters' body weight and firefighter equipment for external resistance. Firefighting equipment is limited in its ability to add additional external resistance compared with barbells, dumbbells, and other resistance training equipment. Thus, the resistance training equipment used by Peterson et al. (²³) may have aided in improving muscular strength and power outcomes to a greater extent compared with this study. Muscular strength and power are important fitness attributes to improve for firefighters, as research has indicated that muscular strength and power are correlated to firefighter physical ability (²⁶).

Differences in training volume may be responsible for the variable findings of Peterson et al. (²³) and this study. The overall training volume used by Peterson et al. (²³) was approximately 17% greater than this study. That is, Peterson et al. (²³) used a 9-week intervention with a training frequency of 3 d·wk⁻¹ and session duration of 60–90 minutes (training volume: 2,025 minutes per subject = 3 d·wk⁻¹ × 75 min·session⁻¹ × 9 weeks). Whereas, the intervention for this study was 12 weeks with a frequency of 2 d·wk⁻¹ and 60 minutes session duration (training volume: 1,680 minutes per subject ∼2 d·wk⁻¹ × 60 min·session⁻¹ × 12 weeks). Training volume has been shown to be a critical factor in determining the magnitude of physiological outcomes, as numerous exercise interventions have demonstrated a dose-response effect (^8,16). The training frequency and volume used in this study were selected because the program was designed specifically to accommodate for the framework of the firefighters' work schedule of 24 hours on-duty and 48 hours off-duty. Therefore, these findings demonstrate this program's efficacy for firefighters who exercise on-duty.

To date, the training effects of a circuit-based program for firefighters have not been evaluated. However, this study demonstrated that circuit training using firefighting equipment is an effective strategy to improve performance of fire ground tasks in some firefighters. Circuit training may be an appropriate mode of training for firefighters due to the stress it places on select energy systems and its logistical properties. Abel et al. (¹) demonstrated that a circuit-based program that uses resistance training equipment can provide the necessary intensity to mimic the aerobic and anaerobic demands specific to the occupational tasks used by firefighters. Although circuit training improved firefighter performance in this study, it is important to understand that circuit training is a single form of training and not an exclusive mode of training for firefighters. Firefighters may benefit over extended periods of time by using a comprehensive strength and conditioning program that focuses on cardiovascular endurance, anaerobic endurance, muscular endurance, strength, and power.

Finally, this study demonstrated that physical training with firefighter equipment was adequate to improve occupational physical ability and anthropometric outcomes of firefighters. Using equipment found in many fire departments for fitness is beneficial in many ways. Many fire departments lack financial resources to purchase fitness equipment for resistance training. However, based on the findings from this study, a lack of financial resources should not be a limiting barrier to implementing a fitness program as there are numerous pieces of fire equipment found on every fire apparatus that can be used to supplement standard fitness equipment. For instance, ladders, charged, and uncharged hose lines, and foam buckets are a few of the pieces of equipment that can be used. Having the equipment within the fire station prevents travel time and fuel cost expenditures that may be incurred if a fitness center is not located within or near the fire station. Finally, using fire equipment allows for greater familiarization of the equipment and allows firefighters to train in a task-specific manner (e.g., advancing charged hose lines, raising, and extending ladders).

Another important finding from this study is that the SEG significantly decreased fat mass (average fat mass loss = 2.5 ± 3.2 kg; Table 3), despite no formal dietary modifications. This outcome is encouraging from health and performance perspectives. From a health standpoint, cardiovascular disease is the leading cause of death among firefighters (²¹), and obesity is a positive risk factor for cardiovascular disease (^10,24). In fact, Durand et al. (¹⁴) reported that 87% of a sample of 527 professional firefighters were classified as overweight or obese. Furthermore, this study found that increasing exercise frequency had favorable effects of cardiovascular disease risk profiles (^4,6,9,14). These findings indicate that it is critical to incorporate exercise programs that facilitate weight management in the fire service. From a performance perspective, the decreased fat mass may, in part, be responsible for the improved SFGT performance of some subjects in the SEG through improved metabolic and work efficiency. Specifically, 2 subjects who were unable to complete the SFGT at baseline were able to complete the SFGT at posttest. These subjects demonstrated an average fat mass loss of 5.7 ± 2.6 kg over the 12-week study. Despite negligible changes in absolute

, it is possible that the decreased fat mass and possibly improvements in muscular endurance and anaerobic capacity (not measured in this study) may have contributed to their improved SFGT performance.

The results from this study also demonstrated that participation in a supervised fitness program 2 d·wk⁻¹ produced significant improvements in absolute resting heart rate and relative

(Table 3). However, changes in cardiorespiratory function have been found to be associated with changes in body mass (¹³). Thus, expressing aerobic capacity in absolute terms and resting heart rate relative to body mass demonstrated that the exercise program did not significantly improve cardiorespiratory function (Table 3). Instead, these changes were body mass dependent.

There are limitations to this study. First, a relatively small sample size decreased the statistical power to identify true differences between groups. Second, we are limited in our ability to compare the effects of this program to a training program using traditional exercise equipment since we did not employ a second training group. Likewise, we are limited in our ability to truly evaluate the independent effect that supervision had on the SEG because we did not have a second training group to perform the same program in an unsupervised manner. Future research should use multiple training groups to further evaluate the effect that periodization strategies, equipment type (traditional vs. firefighter equipment) and supervision have on firefighter outcomes.

Practical Applications

The National Fire Protection Association (²⁰) has recognized the need for firefighters to maintain physical fitness levels to perform occupational activities and reduce the risk of disease. Thus, the NFPA encourages fire departments to implement an on-duty physical training program (²⁰). However, 1 challenge is that many fire departments lack exercise equipment. This study has demonstrated that proper use of existing fire equipment is adequate to improve occupational physical ability and anthropometric outcomes and thus provides all fire departments with an opportunity to enhance firefighter preparedness and health. It is important that qualified personnel design and implement an exercise program that uses fire equipment to enhance safety and promote health, fitness, and performance outcomes.

The distinct physical demands of firefighting make it a unique profession in regards to developing an effective exercise program. Specificity circuit training with firefighter equipment seems to provide an adequate overload stimulus for improvements in fire ground tasks. However, it is likely that circuit training should be supplemented with traditional strength and power training to optimize all of the fitness components associated with firefighting tasks. More highly fit firefighters may require additional training stimuli, higher training intensities, and volume to maintain and improve physical ability levels. Although our outcomes offer good insight as to the role a novel specificity circuit training program can provide, additional research is needed to identify optimal periodization and training strategies. Overall, our results suggest that that implementing a supervised training program using firefighter equipment is safe, feasible, and improves performance outcomes for firefighters.

Acknowledgments

The authors thank the firefighters for participating in this study. The results of this study do not constitute endorsement of any product by the authors or the National Strength and Conditioning Association.