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Relationship of Physical Fitness Measures vs. Occupational Physical Ability in Campus Law Enforcement Officers

Beck, Annie Q.1; Clasey, Jody L.1; Yates, James W.1; Koebke, Nicole C.1; Palmer, Thomas G.2; Abel, Mark G.1

Journal of Strength and Conditioning Research: August 2015 - Volume 29 - Issue 8 - p 2340–2350
doi: 10.1519/JSC.0000000000000863
Original Research

Beck, AQ, Clasey, JL, Yates, JW, Koebke, NC, Palmer, TG, and Abel, MG. Relationship of physical fitness measures vs. occupational physical ability in campus law enforcement officers. J Strength Cond Res 29(8): 2340–2350, 2015—Law enforcement officers (LEOs) on university campuses are required to perform a variety of physical occupational tasks. Identifying which physical fitness characteristics are associated with these occupational tasks will assist in the development of appropriate exercise programs and physical fitness assessments. Therefore, the purpose of this study was to identify physical fitness and demographic characteristics that were correlated with occupational tasks commonly performed by campus LEOs. The occupational assessment was conducted using an Officer Physical Ability Test (OPAT), which simulated a foot chase of a suspect. Sixteen male LEOs (age: 33.1 ± 8.7 years; body mass: 87.2 ± 11.2 kg; height: 179.0 ± 7.9 cm) performed the OPAT. A battery of physical fitness tests were used to assess aerobic capacity, muscular endurance, strength, power, flexibility, agility, and body composition. Bivariate correlations were performed to identify significant (p ≤ 0.05) correlations between physical fitness characteristics and OPAT time. The officers' age was significantly correlated to the majority of OPAT tasks, physical fitness, and anthropometric assessments. Therefore, partial correlations were used to control for the confounding effects of age. After controlling for the officers' age, the overall OPAT time was significantly correlated with agility (r = 0.57) and aerobic endurance (r = −0.65). Furthermore, push-up, curl-up, body mass, waist circumference, and abdominal circumference were significantly correlated to individual OPAT tasks. In conclusion, exercise programs and fitness assessments should be used for campus LEOs that address a variety of physical fitness characteristics associated with occupational performance. In addition, exercise programs should focus on body composition management and fitness for older LEOs.

1Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky; and

2School of Human Services, University of Cincinnati, Cincinnati, Ohio

Address correspondence to Mark G. Abel, mark.abel@uky.edu.

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Introduction

Law enforcement on university campuses can be a physically demanding profession. Similar to other types of law enforcement officers (LEOs), campus LEOs may be required to perform a variety of physical tasks, such as apprehending subjects, running up and down stairs, pushing their body over obstacles, dragging objects, and engaging in a foot chase. Despite the similarity of tasks performed by campus LEOs, protecting a campus does present some unique circumstances. For instance, a large campus may be viewed as “a city within a city” and may contain tens of thousands of students, faculty, and staff with the potential for over 100,000 people present for a major sporting event. The physical environment of campuses typically includes numerous multistory dormitories and structures (e.g., hospitals, office towers, stadiums), which may increase the necessity to perform stair-climbing tasks. Furthermore, the demographic composition of the student body likely contains a greater concentration of young adults who, by nature, are more physically fit (27) compared with the distribution of fitness levels and ages present in typical municipality (1). Thus, despite the similarities in tasks performed, a case may be made that campus LEOs may have a greater likelihood of performing stair-climbing tasks and encountering more physically fit perpetrators. Therefore, it is critical that campus LEOs achieve and maintain sufficient levels of physical fitness to carry out essential job tasks.

Although achieving maximal levels of all physical fitness components may be ideal, there are inherent challenges of improving multiple performance outcomes with competing training stimuli (25). Identifying the specific physical fitness components associated with occupational tasks would provide law enforcement professionals with valuable information regarding the most appropriate physical fitness assessments to evaluate campus LEOs. Furthermore, this information would provide incumbent officers, basic training officers, officer recruits, and tactical strength and conditioning professionals with specific physical fitness outcomes to target as part of the officers' physical training program to more effectively prepare officers for occupational tasks.

Current literature suggests that a large variety of physical fitness and demographic variables are correlated to law enforcement physical ability, including anaerobic and aerobic capacity, upper-body muscular endurance, lower-body power, agility, age, and body mass index (BMI; 26,28,29). However, these studies have not reported consistent findings regarding characteristics that predict law enforcement physical ability. These discrepancies may be because of differences in the law enforcement populations that were evaluated (e.g., Royal Canadian Mounted Police Officers vs. Dutch Police Officers) and the type of physical assessments used (i.e., run test vs. occupation-specific physical ability test). Furthermore, there is a paucity of research focused on evaluating the performance of campus LEOs. Therefore, the primary purpose of this study was to identify physical fitness characteristics that were correlated with the occupational physical ability of campus LEOs. Secondarily, we sought to identify demographic characteristics that were correlated to the occupational physical ability of campus LEOs. Based on previous literature conducted in other tactical populations (26,28,29), we hypothesized that aerobic capacity, muscular strength, agility, age, and body composition would be associated with the occupational physical ability of campus LEOs.

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Methods

Experimental Approach to the Problem

This study used a cross-sectional design to describe the physical fitness levels of campus LEOs and to identify physical fitness and demographic characteristics that were correlated with their occupational physical ability. The independent variables were agility, upper- and lower-body strength, grip strength, low back and hamstring flexibility, abdominal muscular endurance, lower-body power, upper-body muscular endurance, body composition, cardiorespiratory endurance, age, work experience, and anthropometric outcomes. The dependent variables were the time to complete the Officer Physical Ability Test (OPAT) and its individual tasks.

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Subjects

A convenience sample of 16 male campus LEOs between the ages of 24 and 51 years were recruited to participate in this study. The officers were employed by a Division 1 university. Table 1 displays the demographic and physical characteristics of the subjects. Approval for the study's procedures was obtained from the University's Institutional Review Board before the initiation of the study. All subjects provided written informed consent before enrollment in this study. Each subject completed a medical history form. Exclusion criteria for the study were diagnoses of a physical injury that would not allow the officer to perform the tasks. Twenty-six subjects were initially enrolled in the study; 10 subjects dropped out because of various reasons, including time constraints, loss of interest, and illness.

Table 1

Table 1

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Procedures

Subjects participated in 4 testing sessions, and each session was separated by at least 1 day to allow for recovery. The order of tests conducted within a given session was arranged from least to most fatiguing to minimize the effect of fatigue on subsequent tests. Specifically, the testing order was as follows—session 1: body composition, anthropometrics, sit and reach, agility, and maximal bench press and leg press; session 2: 2 practice trials of the OPAT; session 3: official OPAT trial; and session 4: vertical jump, grip strength, curl-up, push-up, and maximal graded exercise test (GXT).

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Body Composition and Anthropometrics

Body composition was assessed via dual-energy x-ray absorptiometry (DXA). Specifically, the DXA was used to quantify the total body fat mass (FM, kilogram), fat-free mass (FFM, kilogram), mineral-free lean mass (MFL, kilogram), and percentage of fat of each subject. The total body DXA scan was performed using a Lunar DPX-IQ (Lunar, Inc., Madison, WI, USA) bone densitometer. The subjects were instructed to remove all objects, such as jewelry or eyeglasses, and wore lightweight shorts and a T-shirt containing no metal. All scans were analyzed by a single trained investigator using the Lunar software (version 10.0).

Anthropometric measurements were taken of the waist, hip, and abdomen according to American College of Sports Medicine Guidelines (1). The test-retest reliability of these circumference measurements in this sample was r ≥ 0.993. Specifically, the waist circumference was measured with a flexible inelastic tape measure at the narrowest part of the torso between the umbilicus and xiphoid process. The hip circumference was taken at the greatest extension of the buttocks. The abdomen circumference was taken at the level of the umbilicus. All measurements were taken in duplicate (to the nearest 0.1 cm) and in rotational order. If any 2 measurements were not within 1 cm, additional measurements were taken until 2 measurements were within 1 cm.

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Flexibility

The sit and reach test was used to assess lower back and hamstring flexibility (Acuflex I; Novel Products, Inc., Rockton, IL, USA). The device has a sensitivity of 1 cm. The test-retest reliability of the sit and reach assessment in this sample was r = 0.998. The footplate of the sit and reach box was set at 23 cm. The subject sat on the floor with the knees extended and feet (without shoes) placed against the edge of the box. The subject's feet were placed 15.2 cm apart. The subject was instructed to keep the knees and arms extended and hands pronated and overlapped while reaching as far forward as possible along the top of the box. The subject held this position for 2 seconds. The farthest measurement of 2 trials was used for data analysis.

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Agility

A change in direction test was used to assess agility. The test-retest reliability of the agility test in this sample was r = 0.968. The test was timed using a handheld stopwatch (Sportline Sport Timer; Sportline, Yonkers, NY, USA). The subject completed a standardized dynamic warm-up, which was led by an investigator. The subject started the test in the prone position behind the start line. Immediately after the starting signal, the subject stood erect and ran 10 m forward, turned right 135° angle and ran 10 m to another cone, turned left 135° angle and proceeded down and back through 3 cones arranged in a “Figure 8” pattern (spaced 3 m apart), turned left 135° angle and ran 10 m to a cone, and turned right 135° angle and ran 10 m to the finish. The subject performed 2 trials, with 3 minutes of recovery between each trial. The fastest trial completed was used for data analysis.

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Upper- and Lower-Body Strength

A standard submaximal (2–5 repetition maximum: RM) testing protocol for free-weight flat bench press and leg press (Nautilus 6000-A leg press; Nebula Fitness Equipment, Columbus, OH, USA) was used to assess upper- and lower-body strength, respectively (4). The subject performed a warm-up set composed of 5–10 repetitions at 40–60% of the subject's estimated 5RM. After 1 minute of recovery, the subject performed 5 repetitions at 60–80% of the estimated 5RM. Three to 5 minutes of rest was provided for each set thereafter, and the load was increased 2.3–4.5 kg per set for bench press and 6.8–9.0 kg per set for leg press until the subject could only complete between 2 and 5 repetitions. The maximal load and repetitions were recorded.

Prediction formulas were used to estimate the 1RM value for bench press and leg press exercises. The prediction equation used for bench press was 1RM = 100 (repetition weight/[102.78 − 2.78 × repetitions]) (6). This prediction equation has demonstrated a high degree of validity compared to actually performing a 1RM (r = 0.993; mean error = 4%; 19). The prediction equation used for leg press was 1RM = (1 + 0.0333 × repetitions) × repetition weight (9). This prediction equation has also demonstrated a high degree of validity for similar field assessments of lower-body strength (r = 0.968; mean error = 0.03%; 19).

Grip strength was measured using a handgrip dynamometer (model 78010; Lafayette Instrument Company, Lafayette, ID, USA) and was included because previous research indicates that grip strength is associated with occupational performance (26). The test-retest reliabilities of this assessment in this sample for the right and left hands were r = 0.940 and r = 0.932, respectively. The subject was instructed to stand erect with the shoulder adducted and neutrally rotated, elbow flexed at 90° angle, forearm in a neutral position, and wrist in slight extension (13). Each subject performed a maximal finger flexion with no extraneous body movements. Three trials were completed by both hands. One minute of rest was provided between trials, and the best score for each hand was used in the analysis.

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Power

Vertical jump was used as an assessment of lower-body muscular power. The test-retest reliability of this assessment in this sample was r = 0.995. The testing protocol used was composed of standardized procedures as presented elsewhere (4). A vertical jump device (Vertec; Sports Imports, Columbus, OH, USA) was used to measure vertical jump height. Standing with both feet flat on the ground and reaching upward with their dominant arm, the subject was asked to touch the highest vein on the device. The subject was instructed to jump straight up as high as possible with the dominant arm and tap the highest vein on the device. No preparatory steps or shuffling were allowed. The test took place on a wood gymnasium floor. Vertical jump height was calculated as the difference between the standing reach and the highest jump reach score. Each subject performed 2 practice trials and 3 official trials. The highest value of the official trials was used in the data analysis.

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Muscular Endurance

The curl-up test was used to assess abdominal muscular endurance using standardized procedures (1). The reliability of this assessment has been reported to be r = 0.98 (8). The subject was instructed to lie supine on a mat with the knees flexed at 90° angle, legs positioned hip-width apart, and arms fully extended at the sides with the middle finger of both hands touching a piece of tape. The first piece of tape was used to mark zero, and a second piece of tape was placed 10 cm beyond the zero marker. A metronome was set at 50 b·min−1 (i.e., rate of 25 repetitions per minute). The subject was instructed to curl up until his middle finger touched the second piece of tape in sync with the metronome. Subjects were required to keep the palms of their hands and the heels of their feet in contact with the mat while the shoulders and head were raised and returned to the mat and the middle finger to the zero marker. The total number of successfully completed repetitions was recorded.

A maximal push-up test was used to assess upper-body muscular endurance. The reliability of similar push-up assessments has been reported to be r = 0.90 (20). The testing procedures were used as described by the American College of Sports Medicine (1) and the State Law Enforcement Council (17). Specifically, the subject maintained a prone position on a mat with the legs together and hands placed on the ground directly under the shoulders with the fingers pointed forward. The starting position was initiated by pushing off the mat with arms fully extended and using the toes as the pivot point. The subject was instructed to keep his body in a straight line with the head up. The subject lowered his body until the chest touched a sponge (height: 7.6 cm). The sponge was used to standardize the downward position for all subjects and is a common procedure for police academy physical fitness testing (17). Each subject was instructed to avoid touching their stomach or thighs to the mat while in the down position. The subject completed as many consecutive repetitions as possible. There was no rest and no time limit for this test. The test was terminated when the subject could not keep proper form or reached failure. The total number of consecutive push-ups was recorded.

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Aerobic Capacity

An aerobic capacity test was performed to measure peak oxygen consumption (V[Combining Dot Above]O2peak). A maximal GXT was performed on a treadmill with a 12-lead electrocardiogram (ECG; ECG-1550A; Nihon Kohden, Tokyo, Japan) to monitor the subjects throughout the test. Before the GXT, each subject ran on the treadmill to select a speed that felt “comfortable.” This speed was used during the GXT. The GXT protocol began with the subject walking for 3 minutes at 80.4 m·min−1. Then, the treadmill speed was increased to the subject's self-selected running speed and the grade was increased every 2 minutes until the subject reached volitional exhaustion. A metabolic cart (TrueOne 2400 Metabolic Measurement System; Parvo Medics, Sandy, UT, USA) was used to measure oxygen uptake in a breadth-by-breadth fashion, and the resulting measures were averaged over 1 minute time intervals. Gas concentrations and flow rate calibrations were conducted before testing. Specifically, O2 and CO2 analyzers were calibrated using gases of known concentrations (O2: 16%; CO2: 4%). Flow rate was calibrated with a 3-L syringe (Series 5530; Hans Rudolph, Inc., Kansas, MO, USA) at rates ranging from 50 to 500 L·min−1. Manual blood pressure measures (Palm Aneroid Sphygmomanometer; American Diagnostic Corporation, Hauppauge, NY, USA) and ratings of perceived exertion (RPE) using a 15-point scale (5) were assessed during the final 30 seconds of each stage of the GXT protocol. The subject's heart rate was continuously monitored during the protocol using the ECG. The test was terminated if the subjects presented adverse symptoms, could not continue, or requested to stop. The following criteria were used to determine whether the subject reached maximal oxygen uptake (V[Combining Dot Above]O2max) or V[Combining Dot Above]O2peak. V[Combining Dot Above]O2max was operationally defined as a plateau in absolute V[Combining Dot Above]O2 (≤0.15 L·min−1) with a concurrent increase in workload or achieved by meeting at least 2 of the following 4 criteria: (a) heart rate equal to or exceeding age-predicted maximal heart rate (220 − age), (b) a plateau in heart rate despite an increase in workload, (c) respiratory exchange ratio ≥1.15, and (d) RPE ≥17. If the subject did not meet these criteria for V[Combining Dot Above]O2max, the highest 1-minute average of oxygen uptake (milliliters·per kilogram·per minute) was used (i.e., V[Combining Dot Above]O2peak) to describe the subject's cardiorespiratory fitness level. Using these operational definitions, 9 (64%) subjects reached V[Combining Dot Above]O2max and 5 (36%) reached V[Combining Dot Above]O2peak. For the purposes of this study, the term “V[Combining Dot Above]O2peak” was used to describe the subjects' aerobic fitness level.

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Occupational Physical Ability

There are several existing standardized occupational physical ability tests for incumbent LEOs, such as the Physical Ability Requirement Evaluation (PARE; revised from the Police Officer's Physical Ability Test: POPAT) and Corrections Officers' Physical Ability Test. However, these tests require specialized equipment (e.g., Power Training Machine), and thus, replicating these tests was not feasible in the present study. Instead, for the purposes of this study, the OPAT was designed to simulate tasks performed by a campus LEO. Identification of the OPAT tasks was based on the recommendation of an expert informant (i.e., University's Police Chief) and based on tasks commonly reported in law enforcement literature (2). The OPAT was performed twice for familiarization purposes on a separate day from the official trial to minimize any effect of residual fatigue and to establish the reliability of the test. These trials were performed in full tactical gear. The test-retest reliability of the OPAT was r = 0.955 and had a standard error of 0.564 seconds from trial 1 to trial 2. To establish the validity of the OPAT, a brief questionnaire was given to the officers. The questionnaire asked the officers to rank the relevancy of each OPAT task and the overall relevancy of the OPAT compared with physical tasks typically performed on the job. The ranking of relevancy consisted of the following scoring: 1 = poor relevance, 2 = fair relevance, 3 = good relevance, 4 = very good relevance, and 5 = excellent relevance. The median (minimum–maximum) response to the relevance of individual OPAT tasks ranged from 4 to 5 (2–5). The median (minimum–maximum) response of the overall relevancy of the OPAT was 5 (3–5).

During the official OPAT trial, the subjects wore full tactical gear, including an armored vest, duty belt with a mock sidearm, and radio. To evaluate the cardiovascular demand of the OPAT, subjects wore a heart rate monitor device (T31 monitor strap; Polar, Kempele, Finland; ActiTrainer recording device; ActiGraph, Pensacola, FL, USA) under their tactical gear. The device's internal clock was synchronized to a personal watch, and each subject's OPAT start and finish times were recorded to identify the appropriate heart rate data to be used for analysis. Heart rate data were downloaded to a personal computer using the manufacturer's software (version 5; ActiLife, Pensacola, FL, USA) and converted to an average heart rate value for the OPAT. Heart rate was expressed in absolute terms (b·min−1) and as a percentage of the subject's maximum heart rate as determined by the peak heart rate identified during the GXT. A stopwatch (Sportline Sport Timer) was used to time the overall OPAT and to quantify the time required to complete each OPAT task. These times were recorded to the nearest tenth of a second. The individual tasks were performed consecutively, without recovery.

Before initiating the OPAT, the subject remained seated in a chair (simulating a patrol car) for approximately 2 minutes. When instructed, the subject stood up and proceeded 2.7 m to a set of 10 concrete stairs (stair ascent 1). After the stair ascent, the subject ran 38.4 m up a slight inclined grade, opened a door, and entered a building (building entry). The subject then proceeded to a second staircase. The subject ascended and descended a flight of 14 stairs (stair ascent/descent). At the bottom of the stairs, the subject turned right and ran 9.8 m and climbed or jumped over a barrier (height = 0.91 m). The subject then ran 159 m on a rubberized track (159 m run). Next, the subject turned right and proceeded to a set of barriers on artificial field turf (barrier maneuver). The subject proceeded 7.3 m and maneuvered over another barrier (height = 0.91 m). Next, the subject ran 4.3 m and jumped over an obstacle (distance = 1.5 m). Then, the subject ran 5.2 m and crawled under a barrier (height = 0.91 m). The subject ran 5.8 m, crawled under another barrier (height = 0.91 m), and dragged a 48.5-kg mannequin a distance of 13.7 m. The mannequin was then turned over in the prone position, and the subject was required to pull the mannequin's wrists together simulating a normal law enforcement cuffing protocol (rescue/arrest). Finally, the subject ran 9.1 m to the finish line (sprint). A 5-second time penalty was added to the total OPAT time if the officer knocked over a barrier. Two officers incurred the 5-second time penalty.

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Statistical Analyses

Basic statistics (mean and SD) were used to describe the subjects' physical fitness and performance outcomes. The normality of each variable's distribution was evaluated with Fisher's skewness coefficient (coefficient = skewness/standard error of skewness). A distribution with a skewness coefficient outside the absolute value of 1.96 was considered to be significantly skewed. In general, the data were distributed normally, except for the curl-up test. The curl-up test was positively skewed (Fisher's skewness coefficient = 2.23) because of the presence of a single outlier. However, we evaluated the data with and without this outlier and determined that the presence or absence of the outlier did not change the outcome of the analysis; regardless, the outlier remained in the analysis. Pearson product-moment correlations were used to identify significant correlations between physical fitness, demographic, and anthropometric measures vs. time to complete the OPAT tasks. The officers' age was significantly correlated to the majority of OPAT tasks, 7 of the fitness measures, and several demographic and anthropometric measures. Thus, partial correlations were used to control for age when assessing the relationship between these predictor variables vs. OPAT task times. Test-retest reliability was assessed using the Cronbach's alpha intraclass correlation coefficient. The level of significance was set at p ≤ 0.05 for all statistical analyses. All analyses were performed using the Statistical Package for the Social Sciences (version 20; SPSS, Inc., Chicago, IL, USA).

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Results

Tables 2 and 3 display the descriptive statistics for the OPAT times and officers' physical fitness outcome measures, respectively. The mean absolute and relative heart rates during the OPAT were 162.7 ± 14.8 b·min−1 and 88.6 ± 4.7%, respectively. The correlations between OPAT performance and physical fitness characteristics are presented in Table 4. The agility test time and the relative V[Combining Dot Above]O2peak were related to the total OPAT time and to 3 of 7 OPAT tasks. The curl-up was related to 2 of 7 OPAT tasks. Absolute V[Combining Dot Above]O2peak and push-up outcomes were related to 1 OPAT task. Despite approaching statistical significance with overall OPAT time, push-up repetitions (p = 0.069), curl-up repetitions (p = 0.076), relative leg press strength (p = 0.116), and vertical jump height (p = 0.159) were not significantly correlated. Furthermore, vertical jump height, relative bench and leg press strength, relative body fat, sit and reach, and grip strength were not correlated to any OPAT task.

Table 2

Table 2

Table 3

Table 3

Table 4

Table 4

Regarding specific tasks, stair ascent 1 was significantly positively correlated to the agility test. The building entry task was significantly inversely correlated with relative V[Combining Dot Above]O2peak and push-up tests. The stair ascent/descent task was significantly positively correlated with the agility test and significantly inversely correlated with relative V[Combining Dot Above]O2peak and curl-up tests. The 159-m run task was significantly inversely correlated with relative V[Combining Dot Above]O2peak and curl-up tests. The barrier maneuver task was not correlated to any physical fitness test. The rescue/arrest task was significantly inversely correlated with absolute V[Combining Dot Above]O2peak. The sprint task was significantly positively correlated with the agility test.

Table 5 displays the correlation matrix between the officers' demographic characteristics and the OPAT task times. After controlling for the confounding effects of age, only age was significantly positively correlated with the overall OPAT time. Regarding specific OPAT tasks, the building entry task was significantly positively correlated with age, body mass, waist circumference, and abdominal circumference. None of the other OPAT tasks were significantly correlated to the demographic or anthropometric characteristics. Furthermore, work experience, standing height, hip circumference, FFM (range across tasks: r = 0.013–0.482), MFL (range across tasks: r = 0.033–0.490), and FM (r = −0.006 to 0.487) were not significantly correlated to any of the OPAT tasks.

Table 5

Table 5

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Discussion

The primary purpose of this study was to identify the physical fitness characteristics that were associated with the occupational physical ability of campus LEOs. The physical fitness characteristics that significantly correlated with the overall OPAT time were agility and aerobic capacity (milliliters·per kilogram per minute). In addition, push-up and curl-up performances were related to multiple occupational tasks. In general, these findings suggest that campus LEOs should have the ability to accelerate quickly in multiple directions and possess sufficient aerobic and muscle endurance to perform physical campus law enforcement tasks.

There is existing literature evaluating relationships between physical fitness and occupational physical ability in LEOs. Stanish et al. (28) conducted a study to identify physical fitness correlates of a PARE in 48 university students and Royal Canadian Mounted Police applicants. The PARE is composed of an obstacle course, push/pull station, and 15-m weight carry (36 or 45.5 kg). The researchers reported that the 1.5-mile run, 1RM bench press, 32-kg bench press for repetitions to failure, 40-m sprint, long jump, and agility run significantly correlated to PARE performance. These results largely support the findings of the present study in that aerobic capacity, agility, and push-ups were identified as significant predictors of occupational LEO performance. Furthermore, despite nonsignificance, strong trends were exhibited in vertical jump performance. These congruent findings indicate that agility, aerobic capacity, upper-body endurance, and lower-body power are important fitness characteristics that may enhance law enforcement physical ability.

Rhodes and Farenholtz (26) also identified fitness characteristics that were correlated to law enforcement physical ability. Specifically, the researchers conducted a similar investigation using the former version of the PARE, the POPAT (26). The POPAT included the following components: an obstacle run, agility station, and push/pull apparatus to simulate gaining control of a suspect. This study found that 55% of the variance on the run component of the POPAT was accounted for by maximal aerobic power and anaerobic capacity. Likewise, the present study also found that aerobic capacity was correlated to occupational physical ability. In addition, Rhodes and Farenholtz (26) found that there were moderate correlations (r = 0.34–0.43) between the fight component of the POPAT vs. push-up, pull-up, sit-up, and grip strength tests. These findings seem logical given that hand-to-hand combat and grappling require upper-body strength and endurance. Unfortunately, the present study did not assess combat performance, rather required officers to drag, turn, and simulate placing cuffs on an anatomically correct mannequin. Collectively, the similarities between these studies suggest that aerobic capacity, anaerobic endurance, and muscular strength and endurance are critical to officers when performing chasing and combative tasks.

The findings of the present study, in combination with the existing literature, suggest that LEOs must optimize numerous physical fitness characteristics to enhance occupational physical ability (i.e., aerobic and anaerobic endurance, muscular endurance, strength, and power). These data raise important questions with regard to identification of the most appropriate training strategy to concurrently enhance numerous competing physical fitness outcomes. In brief, research has indicated an inability to maximize strength gains while concurrently performing endurance exercise (15,32). This potential conflict has been termed the “interference phenomenon” (15). Indeed, at the molecular level, it appears that there are divergent cellular signaling pathways that stimulate muscle hypertrophy vs. mitochondrial biogenesis and that stimulation of the mitochondrial biogenesis pathway may suppress protein synthesis from resistance training (12). Furthermore, a recent meta-analysis has indicated that the frequency and duration of endurance training are inversely associated with hypertrophy, strength, and power outcomes (32). Although research is warranted to evaluate optimal training strategies in LEOs, Garia-Pallares and Izquierdo (11) have provided recommendations for athletes to minimize the interference effect. These recommendations include the following: (a) focus on one strength and one endurance target per training phase, (b) avoid the simultaneous development of local muscular endurance (8–10RM) and maximal aerobic power (95–100% of V[Combining Dot Above]O2max), and (c) attempt to eliminate or minimize residual fatigue from a previous endurance training session by performing strength training before endurance training or provide at least 8 hours of recovery between training sessions.

The secondary purpose of this study was to identify demographic and anthropometric characteristics that were correlated to the occupational physical ability of campus LEOs. This study demonstrated that only the officers' age was positively correlated to the overall OPAT time. Regarding other physical characteristics, body mass and waist and hip circumferences were associated with the building entry task (Table 5). Despite the documented relationship between body mass and physical fitness test performance in other tactical populations (30), we did not identify any other OPAT tasks to be correlated with body mass or other anthropometric outcomes.

Strating et al. (29) also conducted a study to identify correlates of essential physical competency tasks (PCT) in a sample of 6,999 police officers from the Netherlands. The study found that age, gender, and BMI significantly correlated to PCT performance (29). Thus, Strating et al. (29) and the present study found that age and anthropometric measures were correlated to some aspects of occupational physical ability (e.g., building entry task). Specifically, older age and unfavorable anthropometric measures were related to a decrease in work efficiency. In brief, increasing age was likely associated with decreased OPAT performance because many of the significant fitness correlates identified in this study diminish with age (3). These fitness correlates diminish because of several factors, including neural and hormonal changes and decreases in physical activity levels (7,14,22). The positive correlation between anthropometric measures and OPAT performance is concerning for several reasons. First, from a work performance perspective, this relationship emphasizes the importance of maintaining adequate body composition to enhance the efficiency of occupational tasks. Second, from a health perspective, unfavorable anthropometric measures are associated with the incidence of chronic diseases (24). Specifically, a preponderance of body fat stored in the trunk (i.e., android obesity) is associated with an increased risk of the metabolic syndrome, cardiovascular disease, and type II diabetes (18,21,31). In fact, some research indicates that LEOs have a higher prevalence of developing coronary artery disease, metabolic syndrome, and obesity compared with the general population (10). Taken collectively, the findings from these studies suggest that police departments should encourage participation in comprehensive dietary and exercise programs that enhance the body composition of all officers, with an emphasis among older officers.

There are several limitations to this study. First, this study used a cross-sectional design to identify predictors of occupational physical ability. Thus, these results do not infer causality, instead should be viewed as characteristics associated with occupational physical ability. Second, this study used a limited sample size. Despite identifying several significant predictors of occupational physical ability, there were several additional predictors that failed to reach statistical significance. An increased sample size may have changed these findings. Furthermore, it would have been advantageous to use multiple regression analysis to identify predictors of occupational performance. However, that analysis was not possible given the negative effects that a small sample size has on the reliability and generalizability of the developed prediction equation. Third, there were no female participants in this study. Thus, the findings cannot be generalized to female campus LEOs. Additional research is warranted among female officers given that other studies have found that women tend to perform worse on occupational physical ability tests (29). Fourth, not all subjects achieved V[Combining Dot Above]O2max during the GXT. Although not ideal, this is common as research suggests that about 50% of subjects do not demonstrate a plateau in V[Combining Dot Above]O2 when performing maximal exercise (16). Furthermore, it is possible that not all subjects were highly trained or motivated to achieve V[Combining Dot Above]O2max. Fifth, the OPAT was not thoroughly validated according to proposed employment standards (23). However, the purpose of the OPAT was simply to provide an estimate of physical tasks performed on the job, not to be used for punitive or promotional purposes. The tasks included in this test were identified based on the input of an expert informant (i.e., Police Chief), and its level of validity was, in part, supported by the acceptable relevancy survey responses provided by the participating officers, and these tasks were used in previous investigations (26,28). Finally, unlike other investigations (26,28), muscular strength was not identified as a predictor of occupational physical ability. However, this study did not include a true simulation of hand-to-hand combat, where strength has been shown to be a critical factor. Thus, exercise programs for campus LEOs should also focus on the development of muscular strength.

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Practical Applications

The present study found that agility, aerobic endurance, and muscle endurance were associated with the occupational physical ability of campus LEOs. These findings help to identify fitness characteristics that campus law enforcement recruits and incumbent officers should focus on in an exercise program to improve occupational physical ability. Furthermore, these findings indicate that campus law enforcement departments should implement valid and reliable laboratory or field assessments of agility, aerobic endurance, and muscular endurance to evaluate LEO readiness. In addition, we want to reiterate that, despite our nonsignificant findings (likely because of not including a hand-to-hand combat task), muscular strength is an important fitness attribute for campus LEOs, and it should be assessed and developed in a fitness program. Future research should evaluate various periodization strategies (e.g., linear, nonlinear, conjugate, block training) to identify the most effective training model to improve multiple competing fitness outcomes to enhance campus LEO's physical ability. Developing a training program for campus LEOs is challenging given that there are no designated seasons (i.e., off-season, preseason, etc.). Furthermore, tactical strength and conditioning professionals need to determine the most effective approach at training officers on- and off-duty to maximize physiological adaptations while minimizing the effect of residual fatigue.

The present study indicated that the campus LEO's age was correlated to occupational physical ability and physical fitness. Therefore, it is critical that officers maintain adequate physical fitness levels as they age. These findings highlight the importance for police departments to implement a physical fitness program to help officers maintain physical fitness as they age. The mean relative heart rate during the OPAT was 88.3% of maximum, which indicates that officers must be physically fit to work effectively at high intensities. Furthermore, this study found that waist and abdominal circumferences were associated with some occupational tasks. These findings indicate the importance of using weight management strategies for officers, including nutritional and exercise programs.

The current method of physical fitness testing for law enforcement recruits in the state of Kentucky (location of the study) is the Peace Officers Physical Standards (POPS). The POPS testing is used as a requirement for recruits to graduate from the police academy. Other departments and agencies use tests that are similar in composition to the POPS. This test is comprised of bench press (standardized percentage of body weight for maximal repetitions), sit-up test (repetitions per 1 minute), 300-m run, push-up test (repetitions in 2 minutes), and 1.5-mile run. The present study found that agility, aerobic endurance, push-ups, and curl-ups (i.e., muscle endurance) significantly correlated with occupational physical ability in campus LEOs. Therefore, the present study supports the use of most of the current POPS assessments, as they were correlated to our measure of occupational physical ability. Furthermore, we found that agility was correlated to the OPAT. However, agility is not included in POPS testing. Adding this assessment to the POPS testing may provide a more comprehensive assessment of officers' physical fitness as they relate to occupational physical ability.

In summary, campus LEOs have a demanding and potentially dangerous job. Maintaining adequate levels of physical fitness is important to job performance. Exercise programs and fitness assessments for campus LEOs should address the physical fitness components identified in this study that are relevant for their occupational demands. Furthermore, campus law enforcement agencies must emphasize the importance of weight management for all officers and focus on maintaining adequate levels of physical fitness for older officers.

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Acknowledgments

The authors would like to thank the University's Police Department for participating in this study. The results of the present study do not constitute endorsement of any product by the authors or the National Strength and Conditioning Association.

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Keywords:

conditioning; exercise; police; tactical

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