Body Mass Bias Research Articles

Obesity Risk Among West Point Graduates Later in Life.

Szivak, TK, Thomas, MM, Pietrzak, RH, Nguyen, DR, Ryan, DM, and Mazure, CM. Obesity Risk Among West Point Graduates Later in Life. J Strength Cond Res 37(6): 1284-1291, 2023-The purpose of this investigation was to evaluate sex differences in health and fitness outcomes among United States Military Academy (USMA) graduates (class years 1980-2011). Subjects ( n = 701 men, 641 women, age: 45.7 ± 9.3 years) were surveyed as a part of a larger investigation on risk and resiliency factors among USMA graduates. Physical activity was assessed using the International Physical Activity Questionnaire (IPAQ) short form and calculation of weekly metabolic equivalents (METs). Overweight and obesity status were assessed by body mass index (BMI). Significance for the study was set at p ≤ 0.05. Obesity rates for men (30.1%) were significantly higher than for women (16.6%). Men reported significantly higher ( p = 0.01) vigorous METs·wk -1 (1,214.6 ± 1,171.6) than women (1,046.8 ± 1,133.2) despite significantly higher ( p = 0.00) BMI values (28.75 ± 4.53 kg·m -2 ) than women (25.90 ± 5.48 kg·m -2 ). Women were 89% more likely to have ever been on a diet and reported higher (15.2%) Army Body Composition Program enrollment rates than men (6.3%). Obesity rates among men reflect trends seen in the broader military, Veteran, and U.S. adult populations, whereas obesity rates among women were lower. Men may be at a greater risk for obesity later in life despite higher self-reported physical activity; however, lean body mass and self-report bias should be considered. Because lifetime obesity may be influenced by factors other than physical activity, health initiatives should use a comprehensive approach early in the career of military officers.

Accuracy and reliability of the InBody 270 multi-frequency body composition analyser in 10-12-year-old children.

The aim of this study was at examining the validity and reliability of a marketed bioimpedance (BIA) scale for body composition assessment, in children engaged in an educational football project (FIFA 11 for Health). One-hundred and twenty-seven children (70 boys and 57 girls; age 10.7±0.5 years, body mass 41.2±9.0 kg, Body mass index 18.5±3.3 kg·m-2 and stature 149±7 cm) were evaluated for total body mass, lean body mass, muscle mass, using BIA (InBody 270, Biospace, California, USA) and dual-energy X-ray absorptiometry (DEXA, Lunar Prodigy, GE Medical Systems, Madison, Wisconsin, USA), at baseline conditions. Data analyses were carried out separately for girls and boys. Nearly perfect associations (r = 0.97−0.99) and excellent absolute (TEM = 0.04−1.9%) and relative (ICC = 0.98−1.00) inter-device reliability were found between DEXA and BIA variables. Fat and lean body mass bias (p < .0001) were practically relevant both for the boys (2.56 and 11.22 kg, respectively) and the girls (2.33 and 10.49 kg, respectively). Muscle mass and body fat were underestimated and overestimated, respectively, for the boys and girls. InBody 270 is a valid BIA system for estimating body composition with an excellent inter-device relative and absolute reliability. However, the remarkable measurements bias of BIA fat and muscle mass values discourage its use for clinical prescription. The BIA body composition biases were sex dependent.

Influence of Body Mass on Fitness Performance in Naval Special Warfare Operators.

Wood, DE and Swain, DP. Influence of body mass on fitness performance in Naval Special Warfare operators. J Strength Cond Res 35(11): 3120-3127, 2021-U.S. Naval Special Operations Forces have performed some of the U.S. Military's most rigorous missions. The Human Performance Program (HPP) developed a physical performance testing battery to assess and monitor physical fitness. Testing bias relative to body mass has been noted in the past literature, including military physical fitness tests. This retrospective study looked to determine whether there is body mass bias in the HPP fitness assessment and whether an optimum body mass for each fitness test could be determined. Data from 333 subjects (age: 28.4 ± 5.0 years; height: 178.4 ± 6.2 cm; mass: 86.0 ± 9.2 kg) were analyzed to compare body mass with performance on the 8 tests: standing long jump, Pro-Agility test, weighted pull-up, body weight bench press, 1 repetition maximum (1RM) deadlift, 274-m shuttle run, 4.83-km run, and 800-m swim. Linear regression analysis was used to analyze the relationship of body mass to performance; a second-degree polynomial was used to determine best-fit curves for each of the physical fitness tests; analysis of variance was used to examine differences in performance between body mass groups. Significantly better performance for lighter subjects was found in the Pro-Agility test, weighted pull-up, body weight bench press, 274-m shuttle run, and 4.83-km run. Heavier subjects performed better in the 1RM deadlift. Second-degree polynomial regression revealed optimum body mass for the Pro-Agility test, 274-m shuttle run, and 4.83-km run to be 7-16 kg heavier than the lowest body mass. These findings could help professionals better assess and train operators of varying body size.

The Effect of Body Mass on Physical Performance in Naval Special Warfare Operators

The Effect of Body Mass on Physical Performance in Naval Special Warfare Operators Dallas E. Wood, David P. Swain, FACSM. Naval Special Warfare, Virginia Beach, VA, Old Dominion University, Norfolk, VA US Naval Special Operations Forces have performed some of the US Military’s most rigorous missions. The Human Performance Program (HPP) developed a physical performance testing battery to assess and monitor physical performance. Testing bias relative to body mass has been noted in past literature, including military physical fitness tests. PURPOSE: This retrospective study looked to determine if there is body mass bias in the HPP performance assessment and if an optimum body mass for each performance test could be determined. METHODS: Data from 333 subjects (age: 28.4 ± 5.0 yr; height: 178.4 ± 6.2 cm; mass: 86.0 ± 9.2 kg) were analyzed to compare body mass to performance on the eight performance tests: standing long jump, Pro-Agility test, weighted pull-up, body weight bench press, 1-RM deadlift, 274-m shuttle run, 4.83-km run, and 800-m swim. Linear regression analysis was used to analyze the relationship of body mass to performance; a 2nd degree polynomial was utilized to determine best-fit curves for each of the physical performance tests; ANOVA was utilized to examine differences in performance between body mass quartiles. RESULTS: Significantly better performance for lighter subjects was found in the Pro-Agility test, weighted pull-up, body weight bench press, 274-m shuttle run, and 4.83-km run. Heavier subjects performed better in the 1-RM deadlift. Second-degree polynomial regression revealed optimum body mass for the Pro-Agility test, 274-m shuttle run, and 4.83-km run to be somewhat heavier than the lowest body mass. CONCLUSION: These findings could help professionals better assess and train operators of varying body size. The views and opinions expressed are the authors’ and do not reflect those of Naval Special Warfare Command, the US Navy or the Department of Defense.

Load-Carriage Distance Run and Push-Ups Tests: No Body Mass Bias and Occupationally Relevant

Recent research has demonstrated body mass (M) bias in military physical fitness tests favoring lighter, not just leaner, service members. Mathematical modeling predicts that a distance run carrying a backpack of 30 lbs would eliminate M-bias. The purpose of this study was to empirically test this prediction for the U.S. Army push-ups and 2-mile run tests. Two tests were performed for both events for each of 56 university Reserve Officer Training Corps male cadets: with (loaded) and without backpack (unloaded). Results indicated significant M-bias in the unloaded and no M-bias in the loaded condition for both events. Allometrically scaled scores for both events were worse in the loaded vs. unloaded conditions, supporting a hypothesis not previously tested. The loaded push-ups and 2-mile run appear to remove M-bias and are probably more occupationally relevant as military personnel are often expected to carry external loads.

Influence of Body Mass and Size on Performance of the Air Force Physical Fitness Test

Fitness tests for military personnel require primarily weight-bearing activity and are consequently disadvantageous to members with greater body mass. Recent research has developed correction factors for adjusting actual fitness scores in order to remove body mass bias. PURPOSE: To validate these published correction factors for use with US Air Force fitness test components. This study also developed regression models removing all bias due to body weight, body mass index (BMI), and abdominal circumference (AC) measurements. METHODS: Subjects consisted of 533 male and female US Air Force personnel (35.6 ± 6.9 yrs) who completed all 4 components of the Air Force fitness test, consisting of a 1.5 mile run, a one-minute push-up test, a one-minute crunch test, and AC measurements. Published correction factors were used to adjust each fitness test component for body mass. As an alternative to the correction factor method, multiple regression models were developed for each fitness component. The validity of the published correction factors as well as the regression models to remove bias based on body weight, BMI, and AC was determined using the PPM correlation coefficient. RESULTS: For the 1.5 mile run, the corrected run times were not significantly correlated with BMI or AC. However there was a small yet significant correlation between corrected 1.5 mile run times and body weight in both males (-.13) and females (-.14). In females, there was no significant correlation between the corrected push-up or crunch scores and any of the body mass measurements. In males, there were small yet significant correlations between corrected push-up scores and AC (-.15), and between corrected crunch scores and body weight (.17) and BMI (.12). The multiple regression models successfully removed all body mass bias from each fitness component. CONCLUSION: The published correction factors were effective for eliminating body mass bias in push-up and crunch scores in females; however, these correction factors appear to over-correct for 1.5 mile run times in both genders. These correction factors appear to be useful for assessing muscular endurance independent of body mass in US Air Force personnel. For the 1.5 mile run, the developed regression models in this study appear to be an effective alternative method for correction.

Body Mass Bias And Allometric Scaling In The Army Physical Fitness Test Among Infantry Soldiers

Body Mass Bias And Allometric Scaling In The Army Physical Fitness Test Among Infantry Soldiers

Occupational Relevance and Body Mass Bias in Military Physical Fitness Tests

Recent evidence makes a compelling case that US Army, Navy, and Air Force health-related physical fitness tests penalize larger, not just fatter, service members. As a result, they tend to receive lower scores than their lighter counterparts, the magnitude of which can be explained by biologic scaling laws. Larger personnel, on the other hand, tend to be better performers of work-related fitness tasks such as load carriage, heavy lifting, and materiel handling. This has been explained by empirical evidence that lean body mass and lean body mass to dead mass ratio (dead mass = fat mass and external load to be carried/lifted) are more potent determinants of performance of these military tasks than the fitness test events such as push-ups, sit-ups, or 2-mile-distance run time. Because promotions are based, in part, on fitness test performance, lighter personnel have an advancement advantage, although they tend to be poorer performers on many tests of work-related fitness. Several strategies have been proposed to rectify this incongruence including balanced tests, scaled scores, and correction factors--yet most need large-scale validation. Because nearly all subjects in such research have been men, future investigations should focus on women and elucidate the feasibility of universal physical fitness tests for all that include measures of health- and work-related fitness while imposing no systematic body mass bias.

Body Mass Bias in a Competition of Muscle Strength and Aerobic Power

Recently, a fitness competition called the Pump and Run (PR) has been popularized. Composed of 2 events, a 5-km road race time (RT) in seconds and a maximal-repetition bench press (BPR) with resistance based on a percentage of body mass (M), the final score (RTadj) equals RT - 30(BPR). From published findings, the authors hypothesized that the PR would impose a bias against heavier competitors. Furthermore, the potential for age bias in this event has not been evaluated. Therefore, the purpose of this study was to investigate M and age bias in the PR for men and women. For 74 female and 343 male competitors in a large PR event, RT, BPR, M, and age were collected from official competition results. Two subsamples were randomly created from the original sample: the validation (VAL) (54 women and 258 men) and the cross-validation (CVAL) (20 women and 85 men). For the VAL sample, the RTadj showed significant bias against heavier runners (women r = 0.35; men r = 0.28; P < 0.01 for both) but no age bias (women r = 0.04; men r = 0.005; P > 0.05 for both). Using allometric modeling, the authors developed a set of M-based correction factors to be multiplied by each RTadj to yield new adjusted run times (NRTadj) that would be free of M bias. As applied to the CVAL sample, the NRTadj values virtually eliminated the M bias (women r = 0.04; men r = 0.002; P > 0.05 for both) of the current PR scoring system and retained the absence of age bias (women r = 0.02; men r = 0.0002; P > 0.05 for both). The authors recommend the use of the NRTadj scores for future PR competitions.

Correction Factors for Body Mass Bias in Military Physical Fitness Tests

Recent research findings combined with the theoretical laws of biological similarity make the compelling case that all physical fitness test items for the Army, Air Force, and Navy impose a 15 to 20% physiological bias against heavier, not fatter, men and women. Using the published findings that actual scores of muscle and aerobic endurance scale by body mass raised to the 1/3 power, correction factor tables were developed. This correction factor can be multiplied by one's actual score (e.g., push-ups, sit-ups, abdominal crunches, or curl-up repetitions or distance run time) to yield adjusted scores that are free of body mass bias. These adjusted scores eliminate this bias, become better overall indicators of physical fitness relevant to military tasks, are easily applied to the scoring tables used in the present physical fitness tests, and do not reward body fatness. Use of these correction factors should be explored by all military services to contribute to more relevant fitness tests.

Body Mass Penalties in the Physical Fitness Tests of the Army, Air Force, and Navy

Recent research has empirically documented a consistent penalty against heavier service members for events identical or similar to those in the physical fitness tests of the Army, Air Force, and Navy. These penalties, which are not related to body fatness, are based on biological scaling models and have a physiological basis. Using hypothetical cases, we quantified the penalties for men, with body mass of 60 vs. 90 kg, and women, 45 vs. 75 kg, to be 15% to 20% for the fitness tests of these three services. Such penalties alone can adversely affect awards and promotions for heavier service members. To deal equitably with these penalties in a practical manner, we offer two recommendations, i.e., (1) implementation of revised fitness tests with balanced events, in which the penalties of one event for heavier service members are balanced by an equal and opposite bias against lighter service members, or (2) development of correction factors that can be multiplied by raw scores to yield adjusted scores free of body mass bias.

Adjusting Powerlifting Performances for Differences in Body Mass

It has been established that, in the sports of Olympic weightlifting (OL) and powerlifting (PL), the relationship between lifting performance and body mass is not linear. This relationship has been frequently studied in OL, but the literature on PL is less extensive. In this study, PL performance and body mass, for both men and women, was examined by using data from the International Powerlifting Federation World Championships during 1995-2004. Nonlinear regression was used to apply 7 models (including allometric, polynomial, and power models) to the data. The results of this study indicate that the relationship between PL performance and body mass can be best modeled by the equation y = a - bx(-c), where y is the weight lifted (in kg) in the squat, bench press, or deadlift, x is the body mass of the lifter (in kg), and a, b, and c are constants. The constants a, b, and c are determined by the type of lift (squat, bench press, or deadlift) and the gender of the lifter and were obtained from the regression analysis. Inspection of the plots of raw residuals (actual performance minus predicted performance) vs. body mass revealed no body mass bias to this formula in contrast to research into other handicapping formulas. This study supports previous research that found a bias toward lifters in the intermediate weight categories in allometric fits to PL data.

Allometric Modeling of the Bench Press and Squat

Olympic weightlifting and powerlifting are 2 competitive contests of strength that use individual weight categories. Because of the positive correlation between body mass and strength, determining the strongest body mass-adjusted competitor involves using a model that appropriately adjusts for a body mass variable. Allometric modeling (AM), using the index y · x−b, where y is lifting performance, x is body mass, and b is an allometrically derived exponent, has been proposed as an effective method to correct for body mass. However, recent findings have indicated that a second-order polynomial model may be more appropriate than AM when correcting for body mass in Olympic-style weightlifting (clean and jerk, snatch), which is more a measure of power than of powerlifting. Our purpose was to determine whether AM provides an appropriate fit to men's powerlifting (bench press, squat, deadlift) world records, which are more a measure of pure strength. All powerlifting world records as of November 1997 were obtained from the International Powerlifting Federation, and body mass was assumed to be the maximal allowable weight for each competitor. Results indicate that AM of world records for the bench press and squat are void of any body mass bias and contain normally distributed residuals. However, the same cannot be said for the deadlift. Therefore, the AM approach appears to be a satisfactory method of determining the strongest body mass-adjusted men in the bench press and squat. We recommend continued use of AM to compare athletes of different body mass using BP · BM−0.57 and SQ · BM−0.60, where BP is bench press, SQ is squat, and BM is body mass.

Considering body mass differences, who are the world's strongest women?

Allometric modeling (AM) has been used to determine the world's strongest body mass-adjusted man. Recently, however, AM was shown to demonstrate body mass bias in elite Olympic weightlifting performance. A second order polynomial (2OP) provided a better fit than AM with no body mass bias for men and women. The purpose of this study was to apply both AM and 2OP models to women's world powerlifting records (more a function of pure strength and less power than Olympic lifts) to determine the optimal model approach as well as the strongest body mass-adjusted woman in each event. Subjects were the 36 (9 per event) current women world record holders (as of Nov., 1997) for bench press (BP), deadlift (DL), squat (SQ), and total (TOT) lift (BP + DL + SQ) according to the International Powerlifting Federation (IPF). The 2OP model demonstrated the superior fit and no body mass bias as indicated by the coefficient of variation and residuals scatterplot inspection, respectively, for DL, SQ, and TOT. The AM for these three lifts, however, showed favorable bias toward the middle weight classes. The 2OP and AM yielded an essentially identical fit for BP. Although body mass-adjusted world records were dependent on the model used, Carrie Boudreau (U.S., 56-kg weight class), who received top scores in TOT and DL with both models, is arguably the world's strongest woman overall. Furthermore, although the 2OP model provides a better fit than AM for this elite population, a case can still be made for AM use, particularly in light of theoretical superiority.