ACCURACY OF BODY MASS INDEX BASED ON SELF-REPORT DATA AMONG LAW ENFORCEMENT CADETS

1Quincy R. Johnson, 2Jillian M. Joyce, 3Filip Kukić1, 4Robert G. Lockie 5Charles L. Kornhauser, 6Robin M. Orr, 1J. Jay Dawes 1Oklahoma State University, School of Kinesiology, Applied Health and Recreation Stillwater, OK, USA 2Oklahoma State University, Department of Nutritional Sciences Stillwater, OK, USA 3Abu Dhabi Police, Police Sports Education Center, United Arab Emirates 4California State University, Department of Kinesiology Fullerton, CA, USA 5Colorado State Patrol Department Headquarters, Golden, CO, USA 6Bond University, Tactical Research Unit, Robina, Qld, Australia


INTRODUCTION
The physical demands of law enforcement officers (LEOs) range from sedentary (i.e. administrative work) to strenuous (i.e., those such as pursuit, body drag, stair climbing or arresting uncooperative suspects) . In that regard, occupational health and physical performance of LEOs are very important components for safe, effective, and efficient job performance Dawes et al., 2016;Kukić et al., 2018;Steinhardt et al., 1991). For this reason, physical fitness of LEOs is typically a mandatory part of police training and in some law enforcement agencies it is used as a tool for selection of candidates Lagestad & Van Den Tillaar, 2014;Dawes et al., 2019b). Physical fitness could be defined as health-related and performance-related, whereby anthropometrics and body composition play an important role Kukić et al., 2018;Kukić et al., 2020;Riebe et al., 2018). However, the assessment of anthropometrics and body composition is not always feasible due to limited equipment, trained personnel, and/or time. Considering the extent to which increased body mass (BM) relative to body height (BH) can negatively affect the health (Garbarino & Magnavita, 2015;Violanti et al., 2017) and physical performance Dawes et al., 2016) of LEOs, accurate yet feasible methods for evaluation of anthropometric status should be identified for the LEO population. Body mass index (BMI) has been extensively utilized in public and occupational health (Bhaskaran et al., 2018;Ćopić et al., 2020;Ernsberger, 2012; as it only requires a person's BM and BH for the calculation (Eknoyan & Adolphe, 2008;. This is of importance given that people of different sizes may differ in BM merely because they are taller, rather than having greater amounts of body fat. Longitudinal body dimensions, such as BH, follow a particular specific pattern during growth (Kirchengast, 2010), while components of the body that constitute the body volume, such as skeletal and fat tissue, could be altered by physical activity, hypokinesia, nutrition, education, and socioeconomic constructs of society (Dinsa et al., 2012;Kukić et al., 2020;Vuković et al., 2020). Therefore, changes in body composition of adults (i.e., increase or decrease in body fat and/or skeletal muscle mass) often reflect in changes in BM, leading to changes in BMI. Although BMI does not provide specific information on the source of either body volume or size (Provencher et al., 2018;Rothman, 2008), the validity of its utilization relies on consistent associations with biological and socioeconomic factors, such as age, sex, education, occupation, and income (Ball et al., 2002;Boyce et al., 2008;Kukić et al., 2019;Sobal, 1991;Sörensen et al., 2000). In that regard, the World Health Organization and American College of Sports Medicine often times use the standard values of BMI for the evaluation of health status (Riebe et al., 2018;WHO, 2017). These values are easily attainable and are cost-effective, which is of high importance for law enforcement agencies that need to assess large groups of people in a short time. Therefore, multiple studies on LEOs utilized BMI to evaluate obesity rates in LEO populations (Alghamdi et al., 2017;Dopsaj & Vuković, 2015;Kukić & Dopsaj, 2016). Accurate self-report BMI could provide important information about an officer as it provides insights into body status, and indirectly, physical fitness and health (Bhaskaran et al., 2018;Riebe et al., 2018;WHO, 2017). Noting this need for accurate reporting and associated time constraints in a LEO population, research by Dawes et al. (2019a) reported the acceptable accuracy of self-report BMI within a sample of police officers. Considering that cadets are to become LEOs, their ability to accurately self-report BM and BH, thereby BMI could establish standardized procedures for obtaining this information. Moreover, these measures could provide insight into their self-awareness about their body status, which is important if their body status needs improvements. However, acknowledging the work by Dawes et al. (2019a), the accuracy of self-reported measures in law enforcement cadet populations has not yet been established. In that regard, the aim of this study was to evaluate the accuracy of BMI calculated from self-reported BM and BH among a cohort of law enforcement cadet. The researchers hypothesize that self-re ported BH and BM data would not be significantly different from measured values and that accurate reporting would lead to accurate BMI classifications.

Experimental approach to the problem
Self-reported and measured BH and BM data were collected from law enforcement cadets belonging to a US law enforcement agency upon entrance into their respective police academy. This data were then provided to the primary investigator for analysis and comparison.

Subjects
Self-reported and measured BH and BM data for twenty-six (n = 26; males = 23, females = 3) law enforcement cadets (males -age = 31.32 ± 10.04 years; females -age = 25.67 ± 1.53 years) from one US based law enforcement agency located in the Rocky Mountain Region were collected and utilized for this analysis. Prior to data collection, law enforcement cadets were informed of the study's purpose and were asked to provide informed consent allowing investigators to utilize their self-reported BH and BM data, as well as allowing members of the training staff to measure their actual BH and BM. Ethical approval to analyze this information was obtained from the Oklahoma State University Institutional Review Board (IRB 16-041) for human subjects.

Procedures
All self-reported and measured BH and BM measurements were col lected indoors at the law enforcement training facility. Additionally, all data were collected in the morning before training began on the first and second day of training academy. The protocols for collection of these measurements are detailed hereafter.  . Accuracy of body mass index based on self-report data among law enforcement cadets

Results
The descriptive data and comparisons between estimated and measured anthropometrics for this sample are presented in Table II. The results of the paired samples t-tests revealed significant differences in both, estimated and measured BH (t(24) = -4.34, p < 0.001), and estimated and measured BM (t(24) = -2.575, p = 0.017), whereby the differences were trivial size ( Figure 1). However, in this study, the self-reported data had 100% of law enforcement cadets classified into the same National Institute of Health's BMI classification scale as the categories determined using the objective measures. There were no significant differences revealed between estimated and measured BMI (t(24) = 1.104, p = 0.281). Further, when separately evaluating BMI data based on measured BH and BM, it was found that one cadet in this study was "underweight", four were "normal weight", eight were "overweight", 10 were classified as "obesity I", two were classified as "obesity II", and 0 were classified as "obesity III" (Figure 2).

DISCUSSION
The purpose of this investigation was to compare the accuracy of self-reported BH and BM data to measured values among a population of law enforcement cadets, and determine if correct BMI classifications could be determined using self-reported data. It was discovered that law enforcement cadets reported significantly greater BH and lower BM when compared to measured values. However, no significant differences were discovered when calculating BMI based on self-reported or measured data. Based on these results, it appears that self-reported BH and BM data, though less accurate, may allow for an accurate assessment of general weight status via BMI among law enforcement cadets. This is the first study to investigate the accuracy of self-reported anthropometric data in the law enforcement cadet pop ulation. Based on these findings the researchers rejected the hypothesis that self-re ported BH and BM data would not be significantly different from measured values. However, the researchers rejected the hypothesis that no differences in this data would lead to accurate BMI classifications. It seems that the results from this study have implications for strength and conditioning coaches and training staff that are responsible for developing health and wellness interventions for law enforcement cadets, and for researchers and other health experts who, due to time constrictions or resource availability, often must rely on self-reported BH and BM measures in order to stratify law enforcement cadets into groups based on weight status. It may be concluded that self-reported anthropometric data can be used as an easy and cost-effective tool for accurately determining the BMI in this population, despite inaccuracies in self-reported BH and BM. Numerous studies have documented significant differences between measured and self-reported BH status, with the NBP • Journal of Criminalistics and Law Vol. 25, No. 2 . Accuracy of body mass index based on self-report data among law enforcement cadets tendency to overestimate (greater than measured) being very common (Bowring et al., 2012;Nyholm et al., 2007;Wen & Kowaleski-Jones, 2012;Martin et al., 2016). Additionally, differences have also been reported between sexes, where males generally overestimate BH and both sexes underestimated BM (Olfert et al., 2018). Several factors may be responsible for this occurrence including inadequate training regarding BH estimation, self-report bias, and desire to please. The results of this study are consistent with these findings. Self-reported BH significantly differed from measured BH by 0.8% (± 4.6) on average, where cadets overestimated self-reported values. However, these results are in contrast to those presented by Dawes et al. (2019a) who found no significant differences between self-reported and measured BH among LEOs. The results of the current study suggest that cadets tend to be less accurate than LEOs and similar to the general population when providing self-report BH data (Dawes et al., 2019a;Maukonen et al., 2018;Olfert et al., 2018;Bow ring et al., 2012;Nyholm et al., 2007;Wen & Kowaleski-Jones, 2012;Martin et al., 2016). In fact, four law enforcement cadets underreported their BH, 17 over-reported their BH, and four law enforcement cadets were exact in their estimations. However, none of these estimations resulted in a misclassification of BMI for the cadets in this study. For that reason, self-reported BH and BM values can be utilized to accurately calculate BMI in the instance that there are limited resources and/or time to conduct measurements. Previous investigations have illustrated inaccuracies between self-reported and measured BM among general populations (Maukonen et al., 2018;Olfert et al., 2018). Specifically, self-reported BM tends to be underestimated (lower than measured) (Bowring et al., 2012, Nyholm et al., 2007Wen and Kowaleski-Jones, 2012;Martin et al., 2016). Similar to BH, inadequate training regarding BM estimation, self-report bias, and desire to please could contribute to inaccuracies in self-reporting BM. Among the sample of law enforcement cadets in this study, self-reported BM was significantly lower than measured BM by 1.2% (± 2.9) on average. It was discovered that six law enforcement cadets underreported their BM, 15 over-reported their BM, and four law enforcement cadets were exact in their measurement. However, none of these estimations resulted in a misclassification of BMI for the officers in this study. Thus, when used in conjunction with self-reported BH, self-reported BM can serve as a reliable replacement for actual BM measurements if the goal is to calculate BMI and classify cadets based on their weight status. Self-reported BH and BM data have been used in previous research to estimate BMI and overall weight status among both general and tactical populations (Bowring et al., 2012, Nyholm et al., 2007Wen and Kowaleski-Jones, 2012;Martin et al., 2016 logical information (i.e. general health risk or status) and as an alternative anthropometric measure if there are limited resources or access to assess such.
A notable limitation to this study is that it did not analyze the relationship between self-report bias and weight status. That is, assessing whether intentionally underestimating or overestimating BH and BM occurs for specific weight statuses. Previous research conducted by Maukonen et al. (2018) compared self-reported and measured anthropometrics in assessing obesity in adults. The investigators reported that there was a clear tendency for participants classified as overweight and obese to underestimate their BM. Additionally, this bias was much greater in overweight and obese participants than those of normal weight. Furthermore, a low power to detect differences in BMI based on sample size and group stratification, a smaller female sample compared to the male sample, and the accuracy of equipment used by participants and researchers could each be considered a potential limitation. Future studies may find it beneficial to investigate differences between self-reported BH and BM and measured BH and BM between law enforcement cadet groups stratified by weight status and sex (Maukonen et al., 2018).

CONCLUSION
The results of this study suggest that law enforcement cadets inaccurately self-reported both their BH and BM when compared to measured values. Several factors may be responsible for this occurrence including inadequate training regarding BH and BM estimation, self-report bias, and desire to please. However, based on the results of this study, when using a broad BMI classification scale, self-reported BH and BM can be used to accurately determine BMI classification groups. When the ability to objective ly measure BH and BM for BMI determination is not viable for law enforcement staff, self-reported data can be used as a surrogate. However, if any of the data indicates a health risk (i.e. BMI > 25 kg/ m 2 ), or if BH and BM directly relate to occupation al tasks, it is recommended that staff use more accurate and/or additional methods to directly measure BH, BM, BMI, and adiposity.