Comparing the Effects of Different Body Armor Systems on the Occupational Performance of Police Officers

Law enforcement recruit fitness: Changes across the fitness spectrum

BACKGROUND

Law enforcement is a profession of sedentary physical activity interspersed with physically demanding activity that requires high levels of fitness. It is imperative that agencies training law enforcement recruits maximise their fitness during their time at the academy.

OBJECTIVE

The aim of this study was to investigate changes in physical fitness during academy training.

METHODS

Retrospective data for 10 academy recruit classes, totalling 715 participants, were collected from a US law enforcement agency. The change in performance on two standardised tests were used as outcome measures. Comparisons were made between percentiles utilising one-way ANOVA and a linear mixed model (LMM).

RESULTS

Overall, higher percentiles were found to have smaller improvements in physical fitness than lower percentiles. The results of the LMM support this supposition, showing that lower physical fitness scores resulted in greater improvements in a generalised fitness assessment (value = -0.45, standard error 0.02, p <  0.001) and an occupational assessment (value = -0.49, standard error = 0.02, p <  0.001).

CONCLUSION

The results of this study suggest that recruits with lower physical fitness will see greater improvements during academy training. This could be due to a ceiling effect for the more fit but may also be due to recruits of higher physical fitness being under trained during academy. Utilising ability-based training and prescribing an appropriate workload to recruits of higher fitness may improve overall recruit fitness upon graduation.

The comfort and functional performance of personal protective equipment for police officers: a systematic scoping review

This scoping review aimed to identify and summarise evidence on the comfort and functional performance of police officer personal protective equipment (PPE). The Arksey and O'Malley (2005) five-stage framework for scoping reviews was followed. PubMed, CINAHL, Scopus, and Web of Science were searched, and 35 articles were included in the review. The findings show that increased police PPE mass increases heart rate, metabolic energy expenditure, and perceived exertion in response to exercise. Unisex armour designs cause increased discomfort for females with larger bra sizes. PPE reduces joint-specific range of motion, with the design and location impairing movement more than mass. Jumping and sprinting performance is decreased with heavy PPE but unaffected by lighter protection, while agility is compromised with most forms of protection. Future research is needed on the fit and function of PPE for specialist police units, such as mounted police, along with further investigations on how fit can affect functional performance.

The effects of equipment carriage on functional movement quality among law enforcement officers

Law enforcement officers (LEOs) use protective equipment to ensure safety. However, equipment carriage has been shown to impair movement quality and may increase the risk of musculoskeletal injury. Therefore, the objective of this study was to investigate the influence of equipment load carriage on functional movement as measured by the Functional Movement Screen (FMS). It was hypothesised that FMS scores would be negatively impacted by equipment carriage. A counterbalanced cross-over study was utilised and a convenience sample of 31 males and one female active-duty LEOs were included. Participants completed the FMS under two conditions: with and without equipment. Significant median decreases in the equipment condition were observed for hurdle step, shoulder mobility, and rotary stability (p < .01), and deep squat and dominant limb active straight leg raise (ASLR) (p < .05). The non-dominant limb ASLR and trunk stability push-up were similar between conditions (p > .05). Load carriage appears to impair functional movement among LEOs.Practitioner summary: Equipment carriage interferes with functional movement and neither of the two load carriage systems tested were superior to the other. When choosing between duty belt verses duty belt and outer carrier vest carriage, LEO preference, body type, and acclimation to a given carriage type should be considered.

Effects of Thermal Aging on Molar Mass of Ultra-High Molar Mass Polyethylene Fibers

Ultra-high molar mass polyethylene (UHMMPE) is commonly used for ballistic-resistant body armor applications due to the superior strength of the fibers fabricated from this material combined with its low density. However, polymeric materials are susceptible to thermally induced degradation during storage and use, which can reduce the high strength of these fibers, and, thus, negatively impact their ballistic resistance. The objective of this work is to advance the field of lightweight and soft UHMMPE inserts used in various types of ballistic resistant-body armor via elucidating the mechanisms of chemical degradation and evaluating this chemical degradation, as well as the corresponding physical changes, of the UHMMPE fibers upon thermal aging. This is the first comprehensive study on thermally aged UHMMPE fibers that measures their decrease in the average molar mass via high-temperature size exclusion chromatography (HT-SEC) analysis. The decrease in the molar mass was further supported by the presence of carbon-centered free radicals in the polyethylene that was detected using electron paramagnetic resonance (EPR) spectroscopy. These carbon-centered radicals result from a cascade of thermo-oxidative reactions that ultimately induce C–C ruptures along the backbone of the polymer. Changes in the crystalline morphology of the UHMMPE fibers were also observed through wide-angle X-ray diffraction (WAXS), showing an increase in the amorphous regions, which promotes oxygen diffusion into the material, specifically through these areas. This increase in the amorphous fraction of the highly oriented polyethylene fibers has a synergistic effect with the thermo-oxidative degradation processes and contributes significantly to the decrease in their molar mass.

Physical fitness: Differences between initial hiring to academy in law enforcement recruits who graduate or separate from academy

BACKGROUND

Law enforcement agencies often include fitness testing as part of the hiring process. However, it can be months from this testing to when a recruit starts academy.

OBJECTIVE

To determine fitness changes from hiring to academy in recruits who graduate (GRAD) or separate (SEP; do not complete) from academy.

METHODS

Analysis on recruits from one agency, split into GRAD (n = 436) and SEP (n = 78) groups, was conducted. These tests were conducted during initial hiring and academy: push-ups, sit-ups, and arm ergometer revolutions in 60 s; 75-yard pursuit run (75PR); and 2.4 km run. Data were analyzed via a two-way repeated measures ANOVA. Change scores were derived between hiring and academy data for both groups, and analyzed via independent samples t-tests.

RESULTS

Push-ups, 75PR, arm ergometer, and 2.4 km run generally improved (p≤0.001). There were no significant between-group interactions or differences in performance changes for GRAD and SEP recruits. SEP recruits tended to have lesser fitness test performance compared to GRAD recruits.

CONCLUSIONS

GRAD and SEP recruits showed some fitness improvements between initial hiring through to academy. However, SEP recruits with lesser muscular endurance, running speed, and aerobic capacity during hiring did not substantially improve by academy, which likely impacted their academy survivability.

With great power comes great ability: Extending research on fitness characteristics that influence work sample test battery performance in law enforcement recruits

BACKGROUND

Fitness could influence task performance in police officers. Limited research details relationships between different fitness characteristics and police-specific tasks.

OBJECTIVE

Determine relationships between anaerobic and aerobic capacity with police-specific task performance.

METHODS

Data for 308 recruits was analysed. Fitness tests included: push-ups, sit-ups, and mountain climbers (muscular endurance); pull-ups (strength); vertical jump (VJ) and 2 kg medicine ball throw (MBT; power); 75-yard pursuit run (75PR; change-of-direction speed); 201 m run (anaerobic capacity); 2.4 km run and multistage fitness test (aerobic capacity). Police tasks included: 99-yard obstacle course (99OC); 74.84 kg body drag (BD); chain link fence (CLF) and solid wall (SW) climbs; and 500-yard run (500R). Partial correlations controlling for sex and linear regression calculated relationships between fitness and job tasks.

RESULTS

99OC correlated with all assessments; BD only with 75PR. CLF related to the power and aerobic capacity tests, pull-ups, and 201 m run. SW related to VJ, 75PR, pull-ups, sit-ups, 201 m run, and aerobic capacity. 500R related to all except the MBT and 2.4 km run. 75PR and VJ predicted 4/5 tasks.

CONCLUSIONS

Police research has shown the importance of muscular endurance and aerobic capacity. Specific to this studies' correlations, the value of power and change-of-direction speed development for task performance was indicated.

The effect of physical training modality on exercise performance with police-related personal protective equipment

PURPOSE

To investigate the influence of aerobic capacity, muscle strength, and body composition on performance and metabolic demands of men wearing personal protective equipment (PPE).

METHODS

45 men were assigned to one of four groups which significantly differed in upright pull isometric strength (MVC ≤ 1325 N or ≥ 1531 N) and maximum oxygen uptake (VO₂max ≤ 51.9 mL min^-1·kg^-1 or ≥ 56.0 mL min^-1·kg^-1): endurance-trained (low MVC, high VO₂max), strength-trained (high MVC, low VO₂max), endurance- and strength-trained (high MVC, high VO₂max), and untrained (low MVC, low VO₂max). Each participant underwent two test series consisting of a repeated 10 m dummy drag and a graded exercise test wearing either sportswear or PPE of a German riot police unit weighing 20.9 kg (statistics: two-way repeated measures ANOVA, stepwise multiple linear regressions).

RESULTS

With PPE, dummy drag and running performance were impaired by 14 ± 9% and 58 ± 7%. Groups with high MVC dragged the dummy significantly faster than groups with low MVC (17.5 ± 1.8 s/17.6 ± 1.4 s vs. 23.4 ± 5.6 s/22.3 ± 3.5 s). Running distance was significantly higher in groups with high VO₂max (4.5 ± 0.8 km/4.4 ± 0.7 km vs. 3.1 ± 0.5 km/2.8 ± 0.5 km). Body composition variables partially correlated with performance (R ranging from -0.70 to 0.41), but were not significant predictors of the regression models in PPE.

CONCLUSIONS

Individuals who showed a certain degree of aerobic endurance, as well as muscle strength, performed consistently well during the test series. Therefore, none of these variables should be trained in isolation but optimized in combination to be capable in a variety of operational tasks.

Job-Specific Physical Fitness Changes Measured by the Work Sample Test Battery within Deputy Sheriffs between Training Academy and their First Patrol Assignment

Deputy Sheriffs need to exhibit job-specific fitness throughout their occupational lifespan. This study evaluated job-specific fitness changes measured by the Work Sample Test Battery (WSTB) in deputy sheriffs from training academy to patrol school (refresher program completed before first patrol assignment). WSTB data for 34 deputy sheriffs (28 males, 6 females) was retrospectively analyzed. The WSTB included five tests: a 99-yard obstacle course (99OC); a 165-pound body drag (BD); 6-foot chain link fence (CLF) and solid wall (SW) climbs; and a 500-yard run (500R). WSTB task times measured at the end of academy and start of patrol school were compared by paired samples t-tests, percentage change, and effect sizes (all deputy sheriffs combined and by sex). When data for all deputy sheriffs was combined, there were significant time increases for the WSTB tasks at patrol school (p ≤ 0.009; d = 0.45-1.67), except for the BD (p < 0.001; d = 0.80). Male deputy sheriffs exhibited the same changes (p ≤ 0.042, d = 0.40-2.37), with very large CLF and SW decrements (34-83%). Females experienced a significant decline in the 99OC (p = 0.013; d = 0.79), and non-significant declines in all other tasks (p ≤ 0.324; d = 0.50-0.96). Apart from the BD for male deputy sheriffs, job-specific fitness measured by the WSTB declined when deputy sheriffs went on their first patrol assignment. The ability to perform obstacle clearance (CLF, SW) and foot pursuit tasks (99OC, 500R) was particularly reduced. Intervention strategies to aid job-specific fitness maintenance is recommended for deputy sheriffs.

The effects of body armour on mobility and postural control of police officers

BACKGROUND

Police officer use of Individual Light Armour Vests (ILAVs) is increasing due to potential occupational hazards that include blunt trauma, stabbing, and light calibre bullets. It is unclear how addition of this extra load will affect the officer's mobility or postural control.

OBJECTIVES

The aim of this study was to determine the effects of various ILAVs on the mobility and postural control of police officers when compared to wearing their normal station wear.

METHODS

A prospective, within-subjects, repeated measures study was conducted in which officers wore one of three different ILAV variants or normal station wear (N) and acted as their own controls. Officer mobility was assessed via the Functional Movement Screen (FMS) and postural sway (including total sway, average sway velocity, medial-lateral velocity, anterior-posterior velocity, and total excursion area) via force plate.

RESULTS

Significant differences were found between ILAV or N conditions in various components of the FMS, including right Straight Leg Raise, left shoulder mobility, and both right and left quad rotary stability. No significant differences were found in any of the balance measures between these conditions.

CONCLUSION

It appears ILAVs can significantly affect police officer mobility and therefore may contribute to injury risk and decreased ability to complete occupational tasks, though this should be weighed against protective benefits. ILAVs should therefore be carefully selected to minimise injury risk without detracting from occupational performance.

Importance of Agility Performance in Professional Futsal Players; Reliability and Applicability of Newly Developed Testing Protocols

The purpose of this study was to determine the inter- and intra-testing reliability of newly developed tests of the change of direction speed (CODS) and reactive agility (RAG) in competitive futsal players. Additionally, the developed tests were evaluated for their validity with regard to the differentiation of two performance-levels. Thirty-two professional male futsal players (age = 26.22 ± 5.22 years; body height = 182.13 ± 5.99 cm, body mass = 77.43 ± 8.00 kg) participated in the study. The sample was divided into two groups based on their level of futsal performance: A top-level-group (n = 12) and a team-level-group (n = 20). The variables included body height, mass, body mass index, a sprint over a 10-m distance (S10M), and eight newly developed futsal specific CODS and RAG tests. The CODS and RAG tests were performed by dribbling the balls (CODS_D and RAG_D) and without dribbling (CODS_T and RAG_T), and the performances on the dominant and non-dominant sides were observed separately. All CODS, and RAG tests performed on dominant side and RAG_T tests performed on the non-dominant side had good inter-testing (CV = 5–8%; ICC = 0.76–0.89) and intra-testing (CV = 4–9%; ICC = 0.77–0.91) reliability. However, RAG_D performed on the non-dominant side was not reliable (ICC = 0.60, CV = 10%). The top-level-players outperformed the team-level-players in the CODS and RAG tests that involved dribbling (t-test: 4.28 and 2.40, p < 0.05; effect sizes (ES): 0.81 and 1.5, respectively), while the team-level players achieved better results in the CODS_T (t-test: 2.08, p < 0.05; ES: 0.60). The proposed CODS and RAG tests that involved dribbling over a 3.2-m distance, especially on the dominant side, appeared to be reliable, as well as valid for distinguishing the performance level in futsal players.

The Relationship between Fitness and Marksmanship in Police Officers

Police officers may be required to discharge their weapon under physical duress. The purpose of this study was to investigate the relationship between fitness and marksmanship to facilitate future strategies to improve marksmanship. Retrospective data were provided for thirty-four police officers (mean age = 40.48 ± 6.66 years: mean weight = 100.60 ± 19.82 kg: mean height = 180.42 ± 6.87 cm) from a US-based law enforcement agency. Data included four different fitness measures and three different shooting scenarios. No significant relationship was observed between the three different shooting scenarios. There was a significant relationship between shuttle run and static shoot (r = 0.528, p = 0.002), grip strength and the dynamic scenario (r = −0.367, p = 0.035) and leg strength and the positive identification scenario (r = 0.344, p = 0.050). This study demonstrated that a high variety of fitness training and marksmanship practice, under various occupational scenarios, may be required to ensure optimal police shooting accuracy whilst in the field.

Time Spent Working in Custody Influences Work Sample Test Battery Performance of Deputy Sheriffs Compared to Recruits

This study determined the influence of years spent working in custody on fitness measured by a state-specific testing battery (Work Sample Test Battery; WSTB) in deputy sheriffs. Retrospective analysis was conducted on one patrol school class (51 males, 13 females) divided into three groups depending on time spent working in custody: DS24 (<24 months; n = 20); DS2547 (25⁻47 months; n = 23); and DS48+ (≥48 months; n = 21). These groups were compared to a recruit class (REC; 219 males, 34 females) in the WSTB, which comprised five tasks completed for time: 99-yard (90.53-m) obstacle course (99OC); 165-pound (75-kg) dummy drag; six-foot (1.83-m) chain link fence (CLF) and solid wall (SW) climb; and 500-yard (457.2-m) run (500R). A univariate analysis of covariance (ANCOVA) (controlling for sex and age) with Bonferroni post hoc determined significant between-group differences. DS48+ were slower in the 99OC compared to the REC (p = 0.007) and performed the CLF and SW slower than all groups (p ≤ 0.012). DS24, DS2547, and DS48+ were all slower than REC in the 500R (p ≤ 0.002). Physical training should be implemented to maintain fitness and job-specific task performance in deputy sheriffs working custody, especially considering the sedentary nature of this work.

Physical Fitness Characteristics That Relate to Work Sample Test Battery Performance in Law Enforcement Recruits

This study determined relationships between an agency-specific fitness test battery (PT500), and a work sample test battery (WSTB) in law enforcement recruits. Retrospective analysis on 219 males and 34 females from one agency was conducted. The PT500 comprised: push-ups, sit-ups, and mountain climbers in 120 s; pull-ups; and 201 m and 2.4 km runs. The WSTB comprised: 99 yard (90.53 m) obstacle course (99OC); body drag (BD) with a 165 pound (75 kg) dummy; 6 foot (1.83 m) chain link fence (CLF) and solid wall (SW) climb; and 500 yard (457.2 m) run (500R). Partial correlations, controlling for sex, calculated PT500 and WSTB relationships (p < 0.05). Stepwise regression determined whether fitness predicted WSTB performance. The 500R related to all PT500 assessments (r range = −0.127–0.574), 99OC related to all bar push-ups and mountain climbers, and BD related to none. The CLF related to sit-ups, pull-ups, and 2.4 km run; SW related to mountain climbers, pull-ups, and 2.4 km run (r range = −0.127–−0.315). Push-ups, pull-ups, and 2.4 km run were involved in predictive relationships for 99OC, CLF, SW, and 500R (r² range = 0.217–0.500). To perform better in the WSTB and job-specific tasks, developing upper-body strength and aerobic fitness may be beneficial.