Introduction
Numerous studies affirm that firefighting is a physically demanding job. The anxiety caused by unknown conditions, along with the critical sense of time urgency; extreme workload under very hot, polluted (toxic byproducts produced from the fire), and humid environments (water evaporates upon conduct with the fire); and the weight of personal protective equipment (approximately 22.68 kg), including a self-contained breathing apparatus (SCBA), causes firefighters to exhibit extreme physiological responses (8,17,27,30). The intensity of firefighting is illustrated by the high heart rate (Hr) responses recorded during actual (2,12) and simulated (7,17,26) firefighting. In addition, the strenuous nature of firefighting is confirmed by the lactate accumulation recorded in firefighters after performing firefighting tasks (11,22,30).
Despite the demonstrated intense physical requirements of firefighting, not all firefighters maintain appropriate levels of conditioning for peak job performance. Some researchers have found that incumbent firefighters seem to be poorly prepared for the job (14,33), and many are not required to maintain minimum physical capacities or follow a regular exercise routine. According to Womack et al. (33), firefighters have prolonged periods of stress-free activity, but during emergency calls, there is a sudden intense energy demand. If they do not possess adequate levels of physical fitness conditioning, their ability to perform a rescue task may be severely compromised. In addition, Roberts et al. (25) demonstrated that rookie firefighters seemed to have poor physical conditioning that could jeopardize their safety during fire suppression duties.
Studies have demonstrated that the physiological factors related to the performance of occupational tasks can be identified and measured. For example, firefighting requires high levels of physical fitness, and it is well documented that positive firefighter job performance is associated with an increased physical fitness level (6,7,16,17,24,32). Firefighters' cardiovascular fitness has received a great deal of attention (28). Gledhill and Jamnik (10) suggested that the most strenuous firefighting operations demanded an average V̇o2 of 41.5 ml·kg−1·min−1. They demonstrated that the aerobic energy required for performing firefighting tasks ranged from 50 to 85% of V̇o2max. The minimum V̇o2max standard for firefighter applicants recommended by the authors was 45 ml·kg−1·min−1. Furthermore, published reports recommended that firefighters need to have a minimum V̇o2max of 38 ml·kg−1·min−1 (20) or 39 ml·kg−1·min−1 (16). Establishing minimal V̇o2max standards among firefighters could become problematic because firefighting requires additional factors unrelated to aerobic capacity (31). Nevertheless, aerobic capacity is an important contributing factor for performance on many firefighting tasks, particularly those that involve fire suppression.
Strength and muscular endurance are also important factors during firefighting. Firefighters must maintain high levels of strength to be able to lift and carry, often for extended periods, heavy pieces of equipment to the site of an emergency and climb stairs and carry victims to safety. Gledhill and Jamnik (10) described, identified various weights that firefighters may be subjected to during emergencies, in addition to the extra weight that they typically carry (protective clothing and SCBA weight). Some of the weights listed were ladders, 25.40 to 61.23 kg; sand pail used during car accidents, 35.83 kg; Hurst Bacco spreader used during extrications, 32.98 kg; Hurst portable pump, 56.70 kg; advancing hoses produced forces equivalent to weights ranging from 51.71 to 68.04 kg; hoisting hoses produced forces equivalent to weights ranging from 36.24 to 50.35 kg; and removing hoses from aerial storage beds produced forces equivalent to weights ranging from 43.09 to 50.35 kg. In addition, firefighters are required to constantly work against the pressure of charged hoses. In relationship to job performance, upper-body muscular endurance and strength were previously shown to significantly correlate with faster times on consecutive timed firefighting tasks (6,18,24,32). The very nature of firefighting might explain these correlations because many tasks (forceful entries, chopping tasks, hose pull, lift and carry or drag victims, and carry heavy equipment and hoses) require high levels of muscular strength and muscular endurance to perform.
There is a growing body of literature that seeks to clarify the relationship between various aspects of fitness and firefighting job performance. Clearly, performing firefighting tasks is a complex procedure that requires high levels of cardiovascular fitness, strength and muscular endurance. However, there is a need to specify fitness parameters that are important to firefighting. A better understanding of the parameters related to enhanced or decreased firefighting performance would enable firefighters and instructors to prepare adequately for the physical part of the job. Thus, it was the purpose of this study to identify the relationships between various fitness parameters and firefighting performance on an “Ability Test” (AT)-a set of simulated firefighting tasks frequently used by fire departments to assess firefighters' performance. In addition, the study aimed to identify the relationships between fitness parameters and individual tasks of the AT. It was hypothesized that fitness parameters would have significant negative correlations with the total time to complete the AT and with individual AT task times. It was also hypothesized that high body composition variables would correlate with poor performance on the simulated test. It was anticipated that participants capable of completing the AT faster would possess higher fitness levels.
Methods
Experimental Approach to the Problem
The study was divided into 2 phases: first, firefighters performed the AT; approximately 2 weeks later, they underwent fitness assessments. The 2 phases were designed to provide information about firefighters' firefighting ability and physical conditioning, respectively. Numerous studies have demonstrated correlations between fitness parameters and performance on an AT (6,18,24,32). Efforts to improve training and preparation of firefighters have included investigation of relationships between various fitness parameters and job performance. General firefighting performance was assessed using the AT. Empirical support exists for the use of a simulated firefighting test, or AT, to assess performance quality of firefighters. Because firefighters typically work against the clock in responding to emergencies, simulated firefighting training tests typically use total time of completion as an indicator of firefighting performance. Total time on the AT and time on individual tasks of the AT were used as the dependent variables in this study. During the AT, to simulate real-world gear demands, all firefighters wore protective gear with a total weight of 22.68 kg. Firefighting puts demands on all aspects of physical performance, thus a variety of fitness tests were employed, as independent variables, to measure fitness in the areas of body composition, flexibility, muscular endurance, strength, and anaerobic power. Firefighters' musculoskeletal fitness was assessed as firefighting operations analysis (11) determined that the most common applications are lifting heavy objects from the ground to relocate, holding heavy objects for extended periods or repeatedly manipulating objects from waist to shoulder height, dragging or pulling heavy objects, and lifting objects from chest to shoulder level. In addition, abdominal strength was also determined as it is an important parameter both for task performance and for reducing the risk of back injuries (3). Furthermore, trunk flexibility has been suggested as an important parameter for reducing the risk of back injuries (11) and firefighting performance prediction (18). The significant contribution of the anaerobic energy system during firefighting is obvious by the blood lactate levels demonstrated in firefighters (22). This type of activity (all-out efforts/explosiveness) is usually dependent on anaerobic metabolism, thus anaerobic parameters were also evaluated. All fitness tests were conducted by experienced investigators with the help of firefighter instructors who were trained in the proper technique, format, and procedure for all tests. For this study, assessments used to establish the fitness parameters were the same tests that participant firefighters are required, by the fire department, to perform every 6 months; thus, lack of familiarity was not an issue for the participants.
Subjects
Ninety professional male firefighters, with an average age of 33 ± 7 years (range, 22-55 years), volunteered to participate in this study. Because of various reasons such as shift changes, vacation leaves, medical leaves, and job-related injuries, 23 firefighters failed to complete all the measurements. Detailed descriptive statistics for the participants are presented in Table 1. Participants were informed of the experimental risks and signed an informed consent document before the investigation. The investigation was approved by an institutional review board for use of human subjects. The AT sessions took place during the month of November. The environmental conditions were recorded with a weather station monitor (Davis Perception II 7400; Davis, Hayward, CA, USA). The average temperature and humidity during the sessions were 10.56 °C and 35%, respectively.
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Table 1: Firefighters' physical characteristics.*
Procedures
Ability Test
The total time to complete the battery of 6 tests included the time between each task; time started when the firefighters began task 1 and stopped when they finished task 6. Individual task completion times were also recorded. The AT test was administered to all firefighters by the same trained instructors. The test included the stair climb, rolled hose lift and move, Keiser sled, hose pull and hydrant hookup, mannequin (82 kg) drag, and charged hose advance tasks, performed consecutively. The consecutive AT tasks are described as follows:
- Task 1-Stair Climb. The first task involved ascending and descending one flight of stairs consisting of 12 standard steps (24 × 30.5 cm) 8 times.
- Task 2-Rolled Hose Lift and Move. The second task involved moving 6 rolls of hose, for a distance of 4.1 m. Each rolled hose was 9.53 kg, 15.24 m long and 7 cm wide. The rolls were moved, one at a time, from the ground, and set on a bench. When all 6 rolls were placed on the table, the firefighters took one step back from the table. The firefighters then moved the 6 rolls, one at a time, back to the starting position on the floor and placed them in stacks of 2 rolls, as they found them. The firefighters were required to stack the rolls evenly and neatly. Each roll had to be set down. No dropping or throwing of the rolled hoses was allowed.
- Task 3-Keiser Sled. The third task involved striking a 68.8 kg I-beam on a Keiser Sled (Keiser Corporation, Fresno, CA, USA) to a distance of 1.50 m with a 4.1 kg sledgehammer. The firefighters used over-the-head swinging motions to strike the I-beam. Pulling or pushing on the weight to move it faster was not allowed.
- Task 4-Hose Pull and Hydrant Hookup. During the fourth task, the firefighters entered a 2 × 2 m square painted on the concrete next to a fire hydrant and pulled an uncharged (dry) 7-cm-wide fire hose, hand over hand, to a length of 31.5 m. After the hose was in the square, the firefighters had to hook the fire hose to the hydrant. During the process, firefighters removed the small cap from the fire hydrant with their hands and threaded a coupling from the hose onto the hydrant. The coupling had to be threaded on until it could no longer turn by hand. To finalize the fourth event, firefighters removed the coupling by hand and replaced it with the cap that was initially removed from the hydrant. The firefighters were not allowed to go outside the square to perform the task, and the whole hose had to be placed within the 2 × 2 square.
- Task 5-Rescue Mannequin Drag. The fifth task included dragging an 82-kg rescue mannequin for 15.7 m with both hands. The firefighters approached the mannequin from behind, lifted it from the shoulders, and dragged it by walking backward. The event was considered complete when the feet of the rescue mannequin crossed the 15.7 m line.
- Task 6-Charged Hose Advance. For the sixth task, firefighters picked up a nozzle connected to a charged 4.4-cm hose and advanced the line for 15.24 m. When the nozzle of the charged line crossed the finish line, timing for the events was stopped. At this point, the total test time was recorded by the instructors.
Fitness Parameters
Individual test methodologies are described below. Upon entering the room, the firefighter was asked to sit comfortably and relax for 10 minutes. At the end of 10 minutes, radial pulse was recorded for a 1-minute period. The Hr max was estimated using the formula 208 − 0.7 × age (29). Tanaka et al. (29) demonstrated that Hr was strongly inversely related to age (r = −0.90).
Body Composition
Leg-to-leg bioelectrical impedance analysis was conducted using a Tanita single frequency Body Fat Analyzer, model BF-322 (Tanita Corporation of America, Inc., Arlington Heights, IL, USA). Firefighters were instructed to adhere to the following guidelines, before testing: (a) no food or drink within 4 hours of the test, (b) no exercise within 12 hours of the test, (c) no alcohol consumption within 48 hours of the test, (d) and to have an empty bladder within 30 minutes of the test. Each firefighter was asked to stand barefoot on the contact electrodes of the analyzer. Procedures for this test were conducted following the instructor's manual. Hip measurements were obtained at the level of symphysis pubis and the greater protrusion of gluteal muscles. Waist measurements were obtained at the narrowest point above the navel between the xiphoid process and navel (1). Waist and hip circumferences were measured 2 times and recorded to the nearest 0.1 cm. Waist to hip ratio was calculated by dividing the waist by the hip girth.
Flexibility
The sit and reach test, performed on a traditional 32.4-cm-high, 53.3-cm-long box, was used to obtain flexibility measurements for lower back and hamstring muscles (1). The test-retest reliability for this test was reported to be r = 0.94 (13).
Muscular Endurance
The 1 minute sit-up test (23) was used to measure muscular endurance of the abdominal muscles. The total number of properly performed sit-ups was recorded at the end of 1 minute. The test-retest reliability for this test ranged from r = 0.68 to r = 0.91 (13). The maximum push-up test (13) was used to measure muscular endurance of the upper-body muscles. The test-retest reliability for this test was reported to be r = 0.93 (13).
Strength
The 1 repetition maximum (1-RM) test for bench press and squat was used to assess upper- and lower-body strength, respectively. Both tests were administered following the procedure recommended for 1-RM testing by Kraemer and Fry (15). Handgrip dynamometry was used to assess upper-body strength using a handgrip dynamometer-Grip D, model T.K.K. 5401 (Takei Scientific Instruments, Co, Ltd, Tokyo, Japan). The highest measurement for each hand was recorded, and the sum of the high scores for each hand was used for analysis. The test-retest reliability was reported to be r = 0.90 (1). Abdominal strength was determined on an isometric device, ABMED (Abdominal Measuring Device S & B Associates Ltd, Inc, Springdale, AR, USA) (3,4) (Figure). The firefighters were instructed to lie down on the incline bench and support the heels on the footrest platform. A cushioned force arm, attached to a force gauge, was adjusted to the firefighter's chest. The posterior aspect of the ankle at the level of the calcaneus ankle bone was placed on a support platform so that the angle at the knee and hip was approximately 90 degrees. Arms were folded across the chest with opposite arms held securely at the acromion process of opposite shoulder. Firefighters were instructed to exert a gradually increasing force against a cushioned arm until a maximum effort was attained within a 3- to 5-second period. A high-performance strain gauge meter, OMEGA DP41-S (OMEGA Engineering, Inc, Stamford, CT, USA), displayed the force output. The process was repeated 3 times. The highest force output was recorded for later analysis. The test-retest reliability of the ABMED was reported to be high (r = 0.93) (3).
Figure: ABMED (isometric device that measures abdominal strength).
Anaerobic Power (Step Test)
The procedure for the anaerobic step test (AST) was administered following the instructions from Adams (1). The power, in watts (W), was calculated as follows: (W) = ([body weight in kilograms × 10] × 0.40 × number of steps × 1.33])/time in seconds, where 0.40 was the height (40 cm) of the step; 1.33 was a factor that accounts for the eccentric part of the exercise and converts the formula to total work. Total test time was 60 seconds. The test-retest reliability of the AST was reported to be high (r = 0.90) (1).
Anaerobic Power (Vertical Jump)
The vertical jump test was conducted using the Vertek (Sports Imports, Columbus, OH, USA) device. The procedure for the jump test was administered following the instructions from Adams (1). The power was calculated as follows: power (kg·m−1·s−1) = 2.21 × clothed body weight (kilograms) × square root of jump height.
Statistical Analyses
SAS system for Windows V8 was used for analysis of the results. Multiple regression analysis was used to determine the proportion of the variation observed in the AT that was explained by the variation of the fitness parameters. The backward selection method was used in an attempt to identify the subset of useful variables. A second multiple regression analysis was performed to determine the proportion of the variation observed in the AT that was explained by the variation of the important (subset of useful variables) fitness parameters. Pearson-product moment correlation coefficients were calculated among the fitness variable scores and the AT time. In addition, Pearson product moment correlation coefficients were calculated among the fitness parameters and the individual AT tasks in an attempt to identify their importance on each firefighting task. For all statistical analyses, significance was accepted at p ≤ 0.05 unless otherwise stated.
Results
The mean AT performance, overall, and means for individual tasks are presented in Table 2. The descriptive data of the fitness assessments are presented in Table 3. Before analyzing the data, the normality assumption was tested. The univariate procedure demonstrated that all the fitness assessment variables were normally distributed. Shapiro-Wilk tests for normality were tested at p ≤ 0.1 for significance.
Table 2: The firefighter's overall and individual firefighting tasks completion times.*
Table 3: Firefighter's performance on the fitness tests.*
Pearson product-moment correlation coefficients for fitness scores and the AT are presented in Tables 4 and 5. Results demonstrated that the performance on the AT test, based on the time of completion, was related to several fitness and body composition parameters. Negative correlations indicated that higher performance on the fitness variables were associated with faster completion of the AT test, thus higher firefighting performance. Grip strength and 1-RM squat were not significantly correlated with AT time. Poor performance on the AT was significantly correlated (positive correlations) with high resting heart rate, body mass index (BMI), body fat (BF)%, age, and waist size (Table 5). During the AT, individual time of the 6 firefighting tasks was recorded. Pearson product-moment correlation coefficients were also calculated among the fitness variable scores and the individual task times. A number of significant correlations were found; these correlations are presented in Table 6.
Table 4: Intercorrelations among fitness parameters and AT time.†‡
Table 5: Intercorrelations among body composition variables and overall AT time.†‡
Table 6: Correlations among fitness parameters and individual firefighting tasks.†
Multiple regression analysis demonstrated that a significant, F(16,50) = 5.21, p < 0.001, proportion (71%) of the variation observed in the AT was explained by the variation of the fitness parameters. However, multicollinearity existed because several independent variables (fitness and body composition) used in the model exceeded the value 3.45 (variance inflation) that was calculated using the formula 1/(1 − R2). Independent variables with variance inflation greater than 3.45 were more closely related to other independent variable than they were to the AT time (dependent variable). The backward selection method was used in an attempt to identify a subset of useful variables and correct for the multicollinearity. The procedure suggested a reduced model with 5 variables. Multiple regression analyses of the new 5-variable subset model indicated that a significant (F[5,53] = 14.02, p < 0.01) proportion (60%) of the variation observed in the AT was explained by the variation of the fitness parameters used in the model. Multicollinearity did not exist because none of the independent variables used in the model exceeded 1/(1 − R2) = 2.44 (variance inflation, Table 7). Results showed that abdominal strength (t[53] = −2.94, p < 0.01); power, step test (t[53] = −2.37, p < 0.05); push-ups (t[53] = 1.97, p = 0.05); resting Hr (t[53] = 2.64, p < 0.05); and BF% (t[53] = 4.29, p < 0.01) contributed significantly to the predictive power of firefighters' AT performance (Table 7). The equation for the fitted model with R2 = 0.60 is AT time = 3.34 − [(0.05) × (abdominal strength, kilograms)] − [(0.004) × power (step test, watts)] + [(0.023) × (push-ups, #reps)] + [0.038 × (resting heart rate, b·min−1)] + [(0.147) * (Body Fat %)].
Table 7: Parameter estimates (multiple regression analysis).†
Discussion
Firefighting is an extremely physically demanding job (8,17,27,30) that requires high levels of fitness to perform adequately and safely. Comprehending the fitness contribution with respect to firefighting characteristics would enable firefighters to properly prepare for the job requirements. This project primarily aimed to identify the relationships between various fitness parameters-body composition, flexibility, muscular endurance, strength, and anaerobic power and performance on an AT (comprising a set of 6 simulated firefighting tasks). The results demonstrated that the performance on the AT test, based on total time for completion, was related to several fitness and body composition parameters. High performance on several fitness parameters-upper-body strength, abdominal strength, upper-body muscular endurance, and anaerobic power-was shown to be related to high performance on a simulated firefighting task. The correlations (low to moderate, but significant) were in agreement with the values reported in other studies (7,19,24,32). Williford et al. (32) indicated moderate but significant correlations between total time to complete a fire suspension task course and fitness variables such as pull-ups (r = −0.38) and push-ups (r = −0.38). Rhea et al. (24) demonstrated that upper-body muscular endurance and strength were inversely related to total completion time of a test that included 4 firefighting tasks (hose pull, victim drag, stair climb, and equipment hoist), emphasizing the importance of these fitness parameters to firefighting ability. Previously, Michaelides et al. (18) demonstrated that upper-body muscular endurance (push-ups to exhaustion) and upper-body strength (1-RM bench press) were related (r = −0.41, p < 0.05 and r = −0.44, p < 0.05, respectively) to the total completion time of the AT. The characteristics of firefighting might explain these correlations because performing typical firefighting tasks, such as forceful entries, chopping tasks, hose pull, lifting and carrying or dragging victims, and carrying heavy equipment and hoses, requires the use of upper-body muscular endurance and strength.
Firefighters frequently perform tasks in awkward and injury-prone positions that exacerbate their chance of incurring an occupational musculoskeletal injury. There is evidence that maintaining adequate core muscular strength can help prevent injury. Peate et al. (21) showed a reduction in time lost because of injuries and in number of injuries by 62 and 42%, respectively, over a 12-month period as compared with a control group, as a result of an intervention to improve core muscle groups in 433 firefighters. In addition, Cady et al. (5), in a prospective study, evaluated fitness level and incidence of back injuries in 1,652 firefighters for the years 1971-74. Their results demonstrated a 7.1, 3.2, and 0.8% incidence of injury for the least fit, the medium fit, and the most fit firefighters, respectively. The authors concluded that fitness level had a protective effect from back injuries in firefighters. Although the protective effects of abdominal/core strength on work-related injuries were well examined, to our knowledge, none of the studies have investigated the relationship of abdominal strength and ability to perform fire suppression tasks. The most commonly used test to assess core muscles was the sit-up test, which only measures muscular endurance, and its relationship to firefighting performance is still debatable. For example, Rhea et al. (24) reported a nonsignificant negative correlation (r = −0.22) between sit-ups and job performance, using results from 20 firefighters; however, a larger sample size might have produced a significant correlation. Furthermore, they suggested that examining abdominal fitness and body composition may be important in evaluating overall fitness, core stability, and, possibly, the risk of having back injury; but with regard to job performance, the tests showed little relevance. In contrast to these suggestions, other researchers (7,18,32) found that the sit-up test was significantly correlated with overall performance on a simulated firefighting test. Davis et al. (7) included the sit-up variable in a regression model that demonstrated an R2 = 0.90 in a 6-variable regression model used to predict firefighting performance. Williford et al. (32) demonstrated that the sit-up test was significantly related to 5 individual firefighting tasks (forcible entry, hoist, hose advance, victim rescue, and stair climb) used in a simulated firefighting AT. Similar to previous reports (7,18,32), the present study demonstrated that the number of complete sit-ups in 1 minute was significantly correlated with total AT time. In addition, the sit-up test was significantly correlated with the stair climb, the rolled hose lift and move, and the charged hose advance tasks. However, results demonstrated that abdominal strength might be a stronger contributor to firefighting ability than abdominal muscular endurance as determined by the sit-up test. Abdominal strength was significantly correlated with overall performance on the AT and with high performance on all 6 individual simulated firefighting tasks. Multiple regression tests demonstrated that abdominal strength contributed significantly to the predictive power of a firefighter's time to complete the set of firefighting tasks, as described in the AT. Clearly, abdominal training, particularly abdominal strength training, should be an essential aspect of all firefighting training.
A number of studies (7,18,24,32) have explored the relationship between body composition and physical performance in firefighters. This study demonstrated that body composition was significantly related to firefighting performance. Poor performance on the overall AT completion time was significantly correlated with high BMI, BF%, and waist size. High BF% was associated with poor performance on each of the individual 6 tasks, and it was the strongest predictor of a firefighter's time to complete the AT. These results are in agreement with previous studies (18,24,32) that demonstrated positive relationships between %BF and total performance time. Others (24,32) demonstrated a significant positive relationship (r = 0.30) between %BF and total time of firefighting performance, supporting the concept that a high percentage of body fat was associated with poor performance on simulated fire suppression tasks. In addition, one study (7) suggested that excess body fat places an additional burden on the musculoskeletal and cardiovascular systems and it might play a large role in reducing performance among firefighters. Maintaining a desirable body composition would seem to be an important element in ensuring quality firefighter performance.
Perhaps one of the most desirable outcomes of firefighter research would be a clear picture of specific variables that would predict high-level firefighting performance. In this study, multiple regression analysis was used to identify a subset of fitness variables that could predict total time on the AT. Results showed that abdominal strength, power (step test), push-ups, resting Hr, and BF% contributed significantly to the predictive power of a firefighter's AT performance. The subset model indicated that a significant proportion (60%) of the variation observed in the AT was explained by the variation of the fitness parameters used in the model. Davis et al. (7) presented 2 equations that involved field and laboratory fitness variables. The laboratory fitness variables explained 90% (R2 = 0.90) of the variation observed in work capacity, based on 5 sequential firefighting tasks. The equation using the laboratory variables included grip strength, sit-ups, standing long jump, submaximal oxygen pulse, and maximum Hr. The equation using the nonlaboratory variables included push-ups, sit-ups, and grip strength. The nonlaboratory variables explained 54% (R2 = 0.54) of the variation observed in work capacity. Williford et al. (32) used 2 multiple regression models to predict firefighting performance. The first regression model included the 1.5-mile run and the fat-free mass variables. The 2 variables explained 50% (R2 = 0.50) of the variation observed on the 5 sequential firefighting tasks. The second regression model included the 1.5-mile run, fat-free mass, and pull-up variables. These 3 variables explained 53% (R2 = 0.53) of the variation observed on the 5 sequential firefighting tasks. Williams-Bell et al. (31) suggested that 65% of the variance in the Candidate Physical Ability Test was predicted using V̇o2max, body mass, and handgrip strength. Previously, a 6-variable model (sit and reach, resting Hr, 1-RM bench press, 1-RM squat, 1 minute sit-up test, and BF%) was presented that explained 55% (R2 = 0.55) of the variation observed on the AT (18). The regression model suggested in this study increased the explained variation (R2 = 0.60) on the firefighting task performance (AT) by 5% with the use of 5 variables.
There is limited investigation devoted to anaerobic capacity, despite its apparent significant role in firefighting. Unlike aerobic capacity, which can be easily evaluated using a V̇o2max test, there is no single test that has been found to clearly evaluate anaerobic fitness. In fact, anaerobic testing is commonly divided into subcategories such as peak anaerobic power, anaerobic power, and anaerobic capacity. This study used 2 tests to evaluate anaerobic power: the vertical jump test and the AST. The calculated relative power in both tests was significantly correlated with total time to perform the AT. The AST was defined as long AST because of its duration (60 seconds) (1). According to Adams (1), it is more valid to consider this test as a measure of anaerobic power rather than peak anaerobic power or anaerobic capacity, as participants tend to pace themselves to finish the test. Firefighters performed all firefighting simulation tests in a standardized environment; thus, similar to the AST, they had the tendency to pace themselves during simulated firefighting tasks in an attempt to save energy. Tests that others have used to measure anaerobic performance mainly measured anaerobic capacity (24,32) or peak anaerobic power (9). In a study using the 400 m run test to evaluate anaerobic performance among firefighters (24), results demonstrated a strong correlation (r = 0.79, p < 0.05) between total time to complete their simulated test and the anaerobic test. Interestingly, that was the strongest correlation observed in their results. Anaerobic performance was also strongly correlated with all the individual firefighting tasks used in their simulation test. Williford et al. (32) also demonstrated significant association (r = 0.38, p < 0.05) between total test time and performance on the anaerobic test, using the 1.5-mile run to assess anaerobic performance. The 1.5 mile run test was a significant predictor of firefighting performance in the 2 suggested regression models (2-variable model, R2 = 0.50, 3-variable model, R2 = 0.53). One study of 10 incumbent female firefighters (9) determined peak anaerobic power vs. a control group. Peak and average power were assessed using a 30 second Wingate anaerobic power test. The female firefighters did not score significantly greater than the control group in either peak power or average power. Although the study concluded that incumbent female firefighters were reliant on anaerobic power, the authors did not examine the peak anaerobic power needed to perform firefighting tasks and its effects on firefighting ability.
The vertical jump test was previously defined as an explosive strength test; however, the ability to perform well on the vertical jump test might be more related to short anaerobic fitness than to strength because the time (less than 1 second) needed to perform a single jump is not enough to elicit maximal strength (1). Nevertheless, both short and long relative anaerobic power, as calculated in this study, were associated with increased overall performance on the AT. Long anaerobic power contributed significantly to the predictive power of a firefighter's time to complete the AT. Furthermore, high anaerobic power (AST) was significantly correlated with high performance on stair climb, rolled hose lift and move, and charged hose advance tasks. Anaerobic power (vertical jump) significantly correlated with charged hose advance and rescue mannequin drag tasks. That was expected because the aforementioned tasks require high leg power for efficient performance.
To better understand the characteristics of firefighting with respect to the fitness parameters, participants were grouped by pooling the fastest participants on the AT (<5 minutes) in one group and the slowest participants (>9 minutes) in a second group. The faster group performed higher in all fitness parameters and had less %BF and BMI compared with the slower group (Table 8). The larger difference between the 2 subgroups was observed in age. The fastest participants averaged 26 years of age, whereas the slowest participants averaged 38 years of age. A similar method was used by Myhre et al. (19), who presented comparisons between the 5 best and 5 poorest performers. The 5 best performers had greater upper-body strength and upper-body endurance compared with the 5 poorest performers, in their study. However, the most striking difference between the 5 best and 5 poorest performers was their V̇o2max (49.8 vs. 25 ml·kg−1·min−1, respectively). Likewise, von Heimburg et al. (30) demonstrated that 8 faster participants were stronger (13%) than 6 slower participants in terms of a pooled strength index.
Table 8: Fitness and AT performance characteristics of the best performers vs. poorest performers.*†
Firefighters are key components in the maintenance of public safety and security. Better understanding of the factors that contribute to peak performance is critical. The results of this present study introduced new fitness parameters that might be important to a firefighter's job performance. For example, abdominal strength can be fairly easily measured, is important for safety, and, based on the results of this study, relates to a firefighter's job performance. Thus, it might warrant greater attention in firefighter training programs. The results of this study supported the research hypothesis that high performance on several fitness parameters such as upper-body strength, abdominal strength, upper-body muscular endurance, and anaerobic power were shown to be related to high performance on the AT. In addition, it was demonstrated that a significant proportion (60%) of the variation observed in the AT was explained by the variation of the fitness parameters. However, 40% remained unexplained; thus, fitness parameters used alone are not sufficient to fully predict a firefighter's job performance.
Practical Applications
Many of the findings in this study have interesting diagnostic and training implications for strength and conditioning instructors and firefighters. This study may be useful to fire department instructors and trainers in the design and implementation of training programs that are more specifically tailored to improving both individual firefighting skills and general fire suppression performance. Identifying correlations between fitness variables and identifying the contribution of individual variables to the performance of firefighting suppression tasks would enable firefighters to concentrate physical conditioning efforts on those specific variables-such as abdominal strength, upper-body muscular endurance, anaerobic power, and low body fat percentage-that predict high performance. In addition, greater understanding of correlations among individual firefighting tasks and various fitness parameters could help firefighters improve performance on specific firefighting tasks. These findings should also help researchers select or design appropriate measures and protocols for tests of physical performance among firefighters. It is hoped that the findings of this study will contribute to enhanced community safety through improved firefighting performance and decreased risk of occupational injuries.
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