BMI stands for Body Mass Index. It is a measure of body composition. The higher the figure the more overweight you are. Like any of these types of measures it is only a guide, and other issues such as body type and shape have a bearing as well.

Remember, BMI is just a guide - it does not accurately apply to elderly populations, pregnant women or very muscular athletes such as weight lifters. BMI is calculated by taking a person's weight and dividing by their height squared. The standard is to use metric units.

For instance, if your height is 1. If your weight is equipment required: scales and stadiometer required for measuring weight and height.

procedure: BMI is calculated from body mass M and height H. The higher the score usually indicating higher levels of body fat. scoring: Generally, a BMI between 20 and 25 is considered normal weight for height, and outside these values is either underweight or overweight.

Waist size is the missing new risk factor we should be studying. Dr Margaret Ashwell, an independent consultant and former science director of the British Nutrition Foundation, explained at the 19th Congress on Obesity in Lyon, France, May , that waist-to-height ratio is a superior predictor than BMI 7 of type 2 diabetes and cardiovascular diseases.

Ashwell explained that BMI does not take into account the distribution of fat around the body. Abdominal fat affects organs like the kidney, liver and heart more severely than fat around the bottom or hips.

Waist circumference gives an indication of abdominal fat levels. Muscle weighs more than fat it is denser, a cubic inch of muscle weighs more than a cubic inch of fat.

Therefore, BMI will inevitably class muscly, athletic people as fatter than they really are. A 6ft-tall Olympic meter sprinter weighing 90kg lbs may have the same BMI 26 as a couch potato of the same height and weight. There are several ways to measure body weight and composition.

Learn how to tell if you have overweight with these tests, including BMI. Phentermine, a weight loss drug, is not safe to take during pregnancy.

People pregnant, or trying to get pregnant, should stop using the drug…. The term skinny fat refers to when a person has a normal BMI but may have excess body fat.

This can increase the risk of conditions such as diabetes…. Gastric sleeve and gastric bypass surgery are weight loss procedures. They differ in how they lead to weight loss and their effects on the digestive….

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Medical News Today. Health Conditions Health Products Discover Tools Connect. Why BMI is inaccurate and misleading. By Christian Nordqvist — Updated on January 20, BMI exaggerates thinness in short people and fatness in tall people. These results are consistent with the results for Lopes [ 37 ] and Rodrigues [ 38 ].

A possible explanation for this can be the fact that lower BMI means less muscle mass in adolescents, which can affect speed.

However, the results should be interpreted with caution, since overweight or obese persons with a high BMI must overcome greater resistance to weight during the test [ 39 , 42 ].

Artero et al. The results of this study found out an inverted U-shaped or U-shaped curve relationship between BMI and physical fitness in Xinjiang children and adolescents. Given the importance of physical fitness, children and adolescents can keep fit by maintaining a reasonable and normal BMI, thus reducing the incidence of disease caused by low physical fitness.

Therefore, to improve physical fitness, targeted actions should be developed to address BMI-related effects in children and adolescents in Xinjiang.

For example, the Physical Education and Health Curriculum Model of China, which was widely recognized in the field of physical education in China [ 43 , 44 , 45 ], should be carried out to help students maintain a normal BMI; Health courses also should be included in schools to make children and adolescents aware that they should keep a balanced diet and regular exercise.

The government, communities, and families should also be united to take health promotion measures to keep the BMI of children and adolescents within the normal range [ 46 ]. There are some strengths in this study. The first strength is the large provincial representative sample, which has improved the objectivity and accuracy of the results, which has provided help to promote the healthy development of children and adolescents in Xinjiang, China.

However, there are also many limitations. The first limitation lies in the cross-sectional design which prevented the drawing of causal conclusions. Addressing the increasing prevalence of obesity and reduced fitness among children and adolescents, longitudinal studies are still needed to make causal inferences possible.

The second limit is that, except for age and gender, we did not take into account other determinants of physical fitness e. physical activity. The third limitation of the study is that we only measured five commonly used physical fitness and more accurate measures such as body composition were not included.

This research also has some practical application value. First, it provides basis for the physical health intervention for children and adolescents in Xinjiang Uygur Autonomous Region, China.

Secondly, it provides a reference for the government to formulate local public health policies and education policies in the future. This study evaluated the relationship between BMI and fitness in a large sample of children and adolescents in Xinjiang, China. Our result suggested BMI and physical fitness have an inverted U-shaped or U-shaped curve relationship in children and adolescents in Xinjiang, China, that is to say, children and adolescents with a BMI above or below the normal ranges have lower physical fitness than those with normal BMI.

All data generated or analysed during this study are included in supplementary information files. Alves Junior CA, Mocellin MC, Goncalves ECA, Silva DA, Trindade EB.

Anthropometric indicators as body fat discriminators in children and adolescents: a systematic review and meta-analysis. Adv Nutr. Article PubMed PubMed Central Google Scholar. Gillman MW, Block JP. Children with obesity: how are they different?

JAMA Pediatr. Baran M, Celikkalkan K, Cagan Appak Y, et al. Body fat mass is better Indicator than indirect measurement methods in obese children for fatty liver and metabolic syndrome. SciMed J. Article Google Scholar. Hens W, Vissers D, Hansen D, et al. The effect of diet or exercise on ectopic adiposity in children and adolescents with obesity: a systematic review and meta-analysis.

Obes Rev. Article CAS PubMed Google Scholar. Hadwin JA, Lee E, Kumsta R, et al. Cortisol awakening response in children and adolescents with autism spectrum disorder: a systematic review and meta-analysis.

Evid Based Ment Health. Article PubMed Google Scholar. Qin B, Zhou XY, Michael KD, et al. Psychotherapy for depression in children and adolescents: study protocol for a systematic review and network meta-analysis.

BMJ Open. Muller O, Krawinkel M. Malnutrition and health in developing countries. World Health Organization. Department of Nutrition for Health and Development. Nutrition for health and development: a global agenda for combating malnutrition: progress report, vol.

Google Scholar. Ortega FB, Ruiz JR, Castillo MJ, et al. Physical fitness in childhood and adolescence: a powerful marker of health. Int J Obes. Article CAS Google Scholar.

Zhang F, Bi C, Yin X, et al. Physical fitness reference standards for Chinese children and adolescents. Sci Rep. Stodden DF, Goodway JD, Langendorfer SJ, et al. A developmental perspective on the role of motor skill competence in physical activity: an emergent relationship.

Barnett LM, Morgan PJ, Beurden E, et al. Perceived sports competence mediates the relationship between childhood motor skill proficiency and adolescent physical activity and fitness: a longitudinal assessment.

Int J Behav Nutr Phys Act. Cochrane T, Davey RC, Castella FR. Influence of school community and fitness on prevalence of overweight in Australian school children.

Prev Med. Beets MW, Pitetti KH. Med Sci Sports Exerc. Michael WB, Kenneth HP, Bradley JC. Progressive aerobic cardiovascular endurance run and body mass index among an ethnically diverse sample of year-olds.

Res Q Exerc Sport. Kwiecinski J, Konarski JM, Strzelczyk R, et al. Non-linear relationships between the BMI and physical fitness in polish adolescents. Ann Hum Biol. Mak K-K, Ho S-Y, Lo W-S, et al. Health-related physical fitness and weight status in Hong Kong adolescents. BMC Public Health.

Onis MD, Blssner M, Borghi E, et al. Estimates of global prevalence of childhood underweight in and Li YP, Huang WY, Qiqige AY, et al. Prevalence and causes of blindness, visual impairment among different ethnical minority groups in Xinjiang Uygur autonomous region, China.

BMC Ophthalmol. Liu F, Shi B, Li S. Analysis of nutritional status of Kazakh children and adolescents in boarding schools in Xinjiang pastoral areas. Chin J School Health. Bi C, Yang J, Sun J, et al.

Benefits of normal body mass index on physical fitness: a cross-sectional study among children and adolescents in Xinjiang Uyghur autonomous region, China. Plos One. Article CAS PubMed PubMed Central Google Scholar.

Zhang F, Bi C, Yang J, et al. The sex-based disparity in BMI-for-age z-score trends among Xinjiang children and adolescents using four rounds of cross-sectional surveys from to J Public Health.

Bi C, Zhang F, Gu Y, et al. Secular trend in the physical fitness of Xinjiang children and adolescents between and Int J Env Res Public Health. Association CNSSCH. Cohen J. Statistical power analysis for the behavioral sciences.

In: Perceptual and motor skills, vol. Dong Y, Lau PWC, Dong B, et al. Trends in physical fitness, growth, and nutritional status of Chinese children and adolescents: a retrospective analysis of 1·5 million students from six successive national surveys between and Lancet Child Adolesc Health.

Lopes VP, Cossio-Bolanos M, Gomez-Campos R, et al. Linear and nonlinear relationships between body mass index and physical fitness in Brazilian children and adolescents. Am J Hum Biol. Tittlbach SA, Jekauc D, Schmidt SCE, et al.

The relationship between physical activity, fitness, physical complaints and BMI in German adults - results of a longitudinal study. Eur J Sport Sci. Casonatto J, Fernandes RA, Batista MB, et al.

Association between health-related physical fitness and body mass index status in children. J Child Health Care. Gulias-Gonzalez R, Martinez-Vizcaino V, Garcia-Prieto JC, et al. Excess of weight, but not underweight, is associated with poor physical fitness in children and adolescents from Castilla-La Mancha, Spain.

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Body fat scales can be an easy way to track your body fat percentage, but they may not tell the complete story about your health. Accuracy can also…. It is a myth that a pound of body fat contains exactly 3, calories.

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Researchers say the type 2 diabetes drug semaglutide can help people lose weight by decreasing appetite and energy intake. A Quiz for Teens Are You a Workaholic? How Well Do You Sleep? Health Conditions Discover Plan Connect.

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Share this article. Read this next. Medically reviewed by Daniel Bubnis, M. How Accurate Are Body Fat Scales? Accuracy can also… READ MORE. How Many Calories Are in a Pound of Body Fat? Types of Body Fat: Benefits, Dangers, and More. What Are the Three Male Body Types?

READ MORE. How to Calculate Your Basal Metabolic Rate You can easily estimate your basal metabolic rate using the Mifflin-St. Apple, Pear, or Something Else? Body mass index BMI is a calculation that is sometimes used in healthcare settings as an indirect method to determine a person's body weight category.

This BMI calculator can help you learn what this measurement means and how it relates to your health and fitness. BMI is a measurement that takes into account your height, and weight to produce a calculation.

This calculation is a measurement of your body size and can be used to determine how your body weight is related to your height. It is a method of determining whether you may be underweight, average weight, overweight, or obese, but it has flaws.

BMI is not a diagnostic tool nor is it a measurement of body fat percentage. A high BMI may or may not be an indicator of high body fat, but it doesn't necessarily mean that a person is overweight or obese and it alone is not a direct indicator of health.

In some populations, BMI has been found to be a fairly reliable indicator of body fat measures. But the calculation is less effective in other groups, such as bodybuilders and older adults. There are other methods that are more accurate in estimating body fat. Your BMI is calculated using your height and weight.

It can be a starting point for understanding the way your body fat may impact your overall health. You can use the number along with other health measurements to begin a conversation with your healthcare provider about ways to reduce your risk for disease and improve your overall wellness.

Note that BMI is interpreted differently in children. Growth charts and percentiles are used. If children are at or above the 95th percentile of children their age, they are considered obese. For adults, BMI results are interpreted as follows. The reason BMI is used for screening the health of the general population is due to the correlation between being overweight or obese and having certain health problems.

People who are overweight or obese have an increased risk for:. While a high BMI may be an indicator for increased health risk, low BMI can also be indicative of health issues. People who are underweight according to the BMI scale can be predisposed to:.

Maintaining a normal BMI Not only are you less likely to have high blood pressure, heart disease, or diabetes, but maintaining a normal BMI can also help with better sleep, improved circulation, and even better energy throughout the day.

The original index was developed to create statistics about population samples using European men as a baseline. It has since been used to assess people of all ages and races, perpetuating the creators' bias that the male, European body was the ideal body and measure of a person's fit-ness.

There are several known limitations of body mass index. First, the calculation does not take age or gender into account. Men tend to carry more muscle than women and this is not factored into the equation.

BMI does not distinguish between muscle mass and fat mass in its calculation. Also ethnic and race variations are not considered. While BMI can be a tool doctors use to understand your health status better, it is not a solitary diagnostic tool.

When measuring your body fat composition, physicians also take into account your diet, lifestyle, level of physical activity, family history and genetics, as well as other health screenings. Fitness, especially, is very important.

Researchers have found that being fit negates the adverse effects of excess body fat, as well as other traditional cardiovascular risk factors, including obesity, metabolic syndrome, type 2 diabetes mellitus, and hypertension.

Athletes who have higher levels of muscle mass need to be leery of the BMI calculation. Because the BMI number cannot distinguish the different components that make up total body weight, an athlete is better served by using a direct measurement of body composition and body fat.

The BMI calculation is used to screen the general population for health risks related to having too much body fat. This tool does not work well for most athletes who are curious about their body composition. BMI does not measure body fat. If you're interested in knowing your percentage of lean mass versus fat mass there are several methods of assessing a body's percentage of fat.

These methods are referred to as body composition analysis. Some of the most common measurements include:. While body mass index can be a useful tool for some people, it is just one number that should always be considered within the context of other data.

Talk to your healthcare provider about the best way to understand your BMI as part of a comprehensive plan for good health and longevity. Centers for Disease Control and Prevention.

About adult BMI. National Institute of Diabetes and Digestive and Kidney Diseases. Health risks of overweight and obesity. American Heart Association. Body Mass Index BMI in Adults. Eknoyan G.

BMI stands for Body Mass Index. It is a measure of body composition. The higher the figure the more overweight you are. Like any of these types of measures it is only a guide, and other issues such as body type and shape have a bearing as well. Remember, BMI is just a guide - it does not accurately apply to elderly populations, pregnant women or very muscular athletes such as weight lifters.

BMI is calculated by taking a person's weight and dividing by their height squared. The standard is to use metric units. For instance, if your height is 1. If your weight is equipment required: scales and stadiometer required for measuring weight and height.

procedure: BMI is calculated from body mass M and height H. The higher the score usually indicating higher levels of body fat. scoring: Generally, a BMI between 20 and 25 is considered normal weight for height, and outside these values is either underweight or overweight.

The rating scale is the same for males and females. See the table of BMI Norms based on the World Health Organization BMI classification system. You can also use the reverse lookup BMI table for determining your ideal weight based on height.

target population: BMI is often used as a general population measure to determine the level of health risk associated with obesity. advantages: only simple calculations are required from standard height and weight measurements. disadvantages: in certain populations BMI can be inaccurate as a measure of body fatness, for example large and muscular though lean athletes may score high BMI levels which incorrectly rates them as obese.

Second, body composition influences performance on many fitness tests and itself is also an indicator of health. The committee thus defined body composition operationally as a component of fitness, a marker of health, and a modifier of fitness, for the purposes of this report.

Finally, the relationships between body composition, in particular percent body fat, and health outcomes are well established in both youth and adults. Thus, the committee did not collect evidence on the relationship between any body composition field measures and health outcomes.

The committee identified appropriate measures of body composition by selecting field-based items that were valid, reliable, and feasible for implementation in either a national survey or a school or other educational setting. This chapter provides an overview of the existing measures of body composition and presents the committee's conclusions about the best measures of body composition based on their relationship to health in youth, as well as their integrity and feasibility.

The committee's full recommendations for measuring body composition in a national fitness survey and in schools and other educational settings can be found in Chapters 8 and 9 , respectively.

Body weight is a gross measure of the mass of the body. The partitioning and quantification of mass into its basic elements has been a major focus of study historically and has accelerated with the refinement of models Wang et al.

A variety of models and methods—developed largely in adults—have been used to partition body mass into several elements: fat-free mass, fat mass, total body water, fat-free dry mass, and bone mineral. Body composition can be approached at several levels: atomic, molecular, cellular, tissue, and whole body Wang et al.

The technology for measuring specific elements of body mass at each level and factors influencing body composition have been summarized Heymsfield et al. While no single criterion measure of body composition is universally accepted as the gold standard Ackland et al.

DXA provides measures of bone mineral and of fat and lean tissues. The other three laboratory measures have major limitations. Underwater weighing is used to estimate body density, which is then converted to percentage body fat; total body potassium and total body water provide measures of fat-free mass.

Quite often, the laboratory measures are used together especially underwater weighing, total body water, and a measure of bone mineral to provide an estimate of body composition, depending on the model selected see, e.

Several additional laboratory techniques, as well as field measurements available for estimating body composition in youth in various settings e. Critical evaluation of body composition methodology at each level of analysis Wang et al. Further, while laboratory methods—such as DXA, hydrostatic weighing, ultrasound, densitometry, and air displacement plethysmography e.

Some of the equipment also lacks the mobility that may be necessary to access large samples of youth. Overall, the measurement of body composition is dependent on the question being addressed, the information necessary, and the application of the assessment protocols Ackland et al.

For example, techniques used for collecting data to track the health status of a given population epidemiologically will likely differ from those used to collect data to achieve advances in sports performance. Also, many laboratory methods are not feasible for use in the field because of limitations cited earlier.

Direct evaluation of body composition i. Body mass index BMI is used for classification of weight status underweight, normal, overweight, obese , although it does not accurately predict percent body fat Moreno et al.

Accordingly, the selection of body composition measures depends on what element is of interest, which in turn depends on the question s being asked. Given the desirability of a comprehensive understanding of an individual's body composition, as well as considerations of feasibility in practice settings such as schools, the committee focused its review on low-cost field-based measures of body composition.

Laboratory measures, such as DXA, may be appropriate for some national surveys, like the National Health and Nutrition Examination Survey NHANES , for which the equipment is transported in a trailer and only a small sample of youth is studied.

For large national surveys in which youth are tested nationwide in a school setting, however, field-based measures are more suitable than laboratory measures.

Field-based measures include anthropometry skinfolds, weight, height [weight-for-height in the form of BMI], waist circumference and bioelectric impedance analysis BIA. These measures were selected based on their relationship to health markers, their integrity and reliability, and their previous use.

As noted earlier, the fact that body composition is a measure of health is well established. Also well established is that percent body fat is related to health outcomes and that there are various tests with which to measure percent body fat, subcutaneous fat, or abdominal adiposity.

Therefore, the Centers for Disease Control and Prevention's CDC's literature review, described in Chapter 3 , did not include body composition as a fitness component; the CDC review, however, included articles in which body composition appeared as a modifier of fitness or as a health marker or both.

For this reason, the committee considered each such article for inclusion in its review, and this chapter includes findings from selected studies from the CDC review, as well as others, in which body composition was considered as a fitness component, a health marker, or a modifier of physical fitness.

A body of literature from obesogenic intervention research was also reviewed. In addition, the committee reviewed validity and reliability data specific to field tests that measure various aspects of body composition. Further, articles on specific topics related to body composition e.

The following discussion is based on trends described in Malina , and Malina et al. Fat-free mass, fatness, and relative fat distribution in late childhood and adolescence approximate school ages vary with age, between genders, and among individuals of contrasting maturation status.

Age- and gender-related changes are discussed in the subsections that follow. Variation associated with maturation status is then briefly considered.

The principles underlying several methods for estimating body composition warrant special consideration when applied to growing and maturing youth.

It is important to determine when mature adult levels of the primary elements of fat-free mass are reached. This relates to the concept of chemical maturity, defined by Moulton , p.

When adult values of its primary components are reached, fat-free mass is chemically mature. On average, fat-free mass has a growth pattern like that of stature and body mass.

Differences over time until chemical maturity is reached reflect a larger fat-free mass, specifically bone mineral content and skeletal muscle mass in males.

That is, the relative contribution of water to body mass decreases while the relative contributions of solids—protein, mineral, and fat—increase during approximately the first two decades of life, which are dominated by the biological activities of growth and maturation.

Sex differences are apparent during the adolescent growth spurt. On average, fat-free mass in males contains relatively less water and more protein and mineral compared with that in females from childhood into young adulthood Malina et al.

Density of fat-free mass is also greater in males, which reflects primarily sex differences in skeletal muscle mass and bone mineral. These are only average trends, and it should be noted that there are variations among individuals and with biological maturation status and timing.

Although efforts continue to derive more accurate estimates of the chemical composition of fat-free mass, three points should be noted: 1 the composition of fat-free mass changes during growth and maturation, 2 variation among individuals is considerable, and 3 chemical maturity is not attained until late adolescence or young adulthood.

Ideally, equations and constants used to estimate body composition should be adjusted for the chemical immaturity of the fat-free mass in growing and maturing individuals. Fat mass increases more rapidly in girls than in boys during childhood and continues to increase through adolescence in girls Malina, Fat mass appears to reach a plateau, or to change only slightly, near the time of the adolescent spurt in boys around age Malina, Fat mass as a percentage of body mass percent body fat increases gradually during childhood, and sex differences are small.

Percent body fat increases through adolescence in girls; it increases into early adolescence in boys and then declines. The decline during male adolescence is a function of the adolescent spurt in fat-free mass, more specifically muscle mass.

Sex differences in body composition are negligible in childhood, and are established during the adolescent spurt and sexual maturation Malina, Although estimated fat mass is similar in male and female adolescents, females have greater percent body fat. BMI, as a measure of weight-for-height, declines from infancy through early childhood and reaches its lowest point at about age It then increases linearly with age through childhood and adolescence and into adulthood.

Sex differences in BMI are small during childhood, rise during adolescence, and persist into adulthood Malina et al. It has been suggested that individuals who have an early adiposity rebound have an increased probability of being overweight in late adolescence and young adulthood Rolland-Cachera et al.

The concept of adiposity rebound needs further study. In the context of body composition, there is a need to document specific changes in body composition during the rebound.

Does it reflect an increase in fat mass or an increase in fat-free mass? Some evidence suggests the latter Katzmarzyk et al. A skinfold thickness is a double fold of skin and underlying soft tissues, primarily adipose tissue.

Two commonly used skinfolds are the triceps and subscapular. The former increases with age from childhood through adolescence in females, whereas it decreases during the adolescent spurt in males Malina, On the other hand, the latter increases from childhood through adolescence in both sexes.

As a result, the adolescent sex difference in the triceps skinfold is marked compared with the relatively small difference in the subscapular skinfold.

Any number of skinfolds can be and have been measured. Changes in individual skinfolds are variable during growth and specifically relative to the timing of peak height velocity, more so in boys than in girls Malina et al.

Such variation may influence age-associated trends. Fat distribution refers to regional variation in the accumulation of adipose tissue in the body. With advances in technology computed tomography [CT] scans, magnetic resonance imaging [MRI] , attention shifted to abdominal fatness, specifically visceral versus subcutaneous.

With widespread availability of DXA, trunk and extremity distribution of adipose tissue also has received more attention Malina, , Ratios of skinfolds measured on the trunk to those measured on the extremities are commonly used to estimate relative subcutaneous fat distribution.

Ratios of trunk to extremity skinfold thicknesses increase gradually through childhood in both sexes, and there is no sex difference in the ratios. Subsequently, ratios tend to be rather stable in females but to increase in males through adolescence.

Males accumulate proportionally more subcutaneous fat on the trunk than the extremities, while females accumulate relatively similar amounts on both the trunk and extremities Malina, ; Malina and Bouchard, Ratios of trunk to extremity adiposity based on DXA show similar trends He et al.

Ratios of abdominal visceral and subcutaneous adiposity show small differences with age and sex from childhood into early adolescence in normal-weight youth, but males have proportionally more visceral adiposity in later adolescence.

Children and adolescents advanced in maturity status compared with their chronological-age peers tend to be fatter and to have proportionally more subcutaneous fat on the trunk Malina and Bouchard, ; Malina et al. The maturity-associated trend also continues into young adulthood Beunen et al.

Samples in studies using DXA, CT scans, and MRI generally involve several age groups, so that it is difficult to clearly specify maturity differences in each gender.

When it is described, youth typically are grouped by pubertal stage or stages so that several ages are represented within a group Katzmarzyk et al. African Americans have greater total bone mineral content during childhood, adolescence, and adulthood than whites.

Comparisons between Mexican Americans and whites show small differences in fat-free mass and bone mineral content, although Mexican Americans tend to have greater adiposity. Data for skinfolds indicate proportionally more subcutaneous adipose tissue on the trunk in African Americans, Mexican Americans, and Asian Americans compared with whites.

In contrast, data on the distribution of visceral and subcutaneous adiposity overlap among ethnic groups. This section considers body composition as both a modifier of physical fitness and a health marker.

Body composition is one of many factors that influence performance on laboratory- and field-based tests of physical fitness. Fat-free mass and its major tissue component, skeletal muscle mass force-generating tissue of the body , obviously are important to performance on many tests.

Absolute fat-free mass is significant in tests requiring the projection of objects e. Fat-free mass also is highly correlated with height in children and adolescents.

Fat mass and percent body fat are more variable, but excess fatness absolute and relative tends to exert a negative influence on performances on fitness tests that require movement or projection of the body through space i.

Two studies of national samples of Belgian youth considered relationships between the sum of skinfolds four in boys, five in girls and a variety of fitness tests Beunen et al.

Among males aged , partial correlations controlling for height and body mass and several relevant fitness test items static arm pull strength, sit-and-reach, vertical jump, left lifts, flexed arm hang, agility were negative and low to moderate, —0. Corresponding partial correlations in girls aged ranged from —0.

Comparison of the fattest and leanest 5 percent of participants highlighted the negative influence of excessive subcutaneous fatness for all fitness test items except sit-and-reach, arm pull strength, and PWC Differences in flexibility were negligible.

The fattest were absolutely stronger boys and girls and generated more watts girls only , reflecting their larger body size. The fattest youth of both sexes also were advanced in skeletal maturation compared with their leanest peers of the same age groups Beunen et al.

Trends were generally similar in more recent samples of normal-weight and obese youth. Low levels of cardiorespiratory endurance were associated with percent body fat in African American and white adolescents Gutin et al. Studies evaluating the relationship between BMI and fitness tests generally have focused on the negative influence of obesity Chatrath et al.

Correlations between BMI and indicators of fitness tended to be linear in well- and undernourished children aged Malina et al. A recent study with a representative sample of Brazilian youth showed that, after adjusting for potential confounding factors, weight and BMI were negatively correlated with performance on the long jump, curl-up, pull-up, 9-minute run, meter run, and 4-meter shuttle run Dumith et al.

Data on variations in fitness across the broad spectrum of BMI within relatively narrow age groups are limited. Relationships between BMI and fitness varied among fitness test items in four age groups—, , , and —in a national sample of Taiwanese youth Huang and Malina, Correlations were low to moderate and did not vary among age groups or between sexes.

In a national sample of Taiwanese youth Huang and Malina, , sex-specific regressions of fitness items on BMI, using a nonlinear quadratic model, indicated differential effects for individual tests, which varied with age and sex.

Relationships for the sit-and-reach were similar and slightly curvilinear in girls aged and boys aged , but were parabolic among girls aged and boys aged Peaks of the parabola were sharper in adolescent boys than in adolescent girls. Youth of both sexes aged with either higher or especially lower BMIs had the poorest flexibility.

Relationships for sit-ups were similar in girls and boys aged The decline was initially slight but accelerated with increasing BMI, more so in girls. The relationship between BMI and performance on sit-ups was parabolic in youth aged , more so in boys.

The relationship was curvilinear in other age groups of boys and all age groups of girls, and was especially parabolic in boys aged Excessive adiposity and especially abdominal obesity have been associated with risk factors for cardiovascular disease and metabolic syndrome in youth e.

The Bogalusa Heart Study, a longitudinal study investigating the risk factors for cardiovascular disease since , provides many insights into the relationship between different measures of body composition and cardiovascular health in a biracial population African American and white.

The study found that by age 10, 60 percent of children who were overweight had at least one biomarker or risk factor for cardiovascular disease Freedman et al. More than one cardiovascular disease risk factor besides body weight was seen in 49 percent of overweight and 60 percent of obese adolescents May et al.

Other studies have confirmed these findings, suggesting that elevated weight status is associated with increased risk for cardiovascular disease Chang et al. Markers of metabolic syndrome a cluster of precursory risk factors also are associated with elevated childhood weight status Rizzo et al.

For example, obese youth have an increased risk for prediabetes compared with nonobese youth Li et al. Among overweight children, those with prediabetes had 4 percent lower bone mineral content than those without prediabetes Pollock et al.

Higher levels of body fatness predicted from skinfolds have been linked to increased cardiovascular disease risk in youth Going et al. Estimated fatness levels above 20 percent in boys and 30 percent in girls were associated with risk factors for cardiovascular disease and metabolic syndrome, especially elevated C-reactive protein and insulin levels Going et al.

The location of adipose tissue stores also influences cardiometabolic risk. Compared with more generalized obesity measured as BMI , abdominal obesity was more strongly associated with risk of myocardial infarction, stroke, and premature death in adult men Larsson et al.

Waist circumference has been associated with cardiovascular risk factors such as insulin levels Bassali et al. A review of the adult literature, however, found that neither waist circumference nor BMI had superior discriminatory capability in identifying cardiovascular disease risk Huxley et al.

Abdominal adipose tissue also was associated with higher blood pressure, type 2 diabetes, and dyslipidemia in adults, but the relationship remains unclear in children Daniels et al.

Nevertheless, relationships between markers of disease risk and body composition were noted in school-aged youth in the Bogalusa Heart Study, specifically among African American girls aged , in whom a cm increase in waist circumference was associated with a decrease in concentration of HDL cholesterol and increases in triacylglycerol and insulin Freedman et al.

The association with the risk factors was stronger for waist circumference than for skinfold thickness subscapular and triceps measurements. In overweight children, neither BMI nor the sum of skinfolds was a good predictor of risk factors for cardiovascular disease; a measure of fat distribution waist-to-height ratio was a better predictor of cardiovascular risk factors low-density lipoprotein [LDL] cholesterol, HDL cholesterol, fasting insulin, and systolic and diastolic blood pressure Freedman et al.

Evidence for the contribution of measures of body composition to cardiovascular health also was noted in the European Youth Heart Study. Among children aged 9 and 15 from Denmark, Estonia, and Portugal, waist circumference and the sum of skinfolds were associated with clustered cardiovascular disease risk, determined by a composite score of systolic blood pressure, triglycerides, insulin resistance using the homeostasic model assessment-insulin resistance [HOMA-IR] level , and ratio of total cholesterol to HDL Andersen et al.

The relationship between weight status and risk for cardiovascular disease tends to track from childhood and adolescence into adulthood Freedman et al. For example, changes in BMI and childhood blood pressure were found to be strongly correlated with adult blood pressure in both sexes Lauer and Clarke, Based on logistic models developed with BMI data from youth aged and adults aged in the Fels Longitudinal Study, childhood and adult obesity are related, and the risk becomes stronger in adolescence Guo et al.

Another analysis of data from the Bogalusa study showed that the sum of skinfold thicknesses triceps and subscapular measurements and BMI z-score in childhood were the main contributors to higher levels of high-sensitivity C-reactive protein in adults, a risk factor for cardiovascular disease.

The effect of skinfold thicknesses was greater in African Americans than in whites and in girls than in boys Toprak et al. A recent systematic review of the tracking of obesity and its association with metabolic risk in adulthood, however, suggests that weight status and cardiometabolic risk factors should perhaps be considered independently of each other, given the limitations of current research designs Lloyd et al.

Finally, analysis of data from the Bogalusa study shows that BMI and subscapular skinfold measurements are positively correlated with the risk of becoming a diabetic adult Nguyen et al.

In summary, indicators of body composition, specifically adiposity, are determinants of health. Health implications of fat-free mass in youth apparently have not been systematically addressed. By definition, field-based measurements such as skinfolds, BMI, and waist circumference are, to a large extent, indirect estimates of body composition.

The advantages of field measures include minimal subject burden, adequate reliability in the hands of trained technicians see more on quality control in Annex , and relatively rapid data acquisition for a large number of subjects. Limitations include reduced accuracy, high variability, and lack of broad applicability in all populations.

The validity of field-based measurements is usually assessed by comparison with laboratory measures e. Although evidence for the validity of field-based measures of body composition is variable see below , their associations with markers of health risk justifies including them in a survey of youth fitness.

It is important to note that the accuracy of anthropometric measures is strongly dependent upon the experience and training of technicians in implementing the measurements.

Care in interpreting the data also is necessary in working with youth. Elements of body composition, especially bone mineral content, also may be influenced by regular physical activity Strong et al.

BMI is an indicator of weight-for-height. As discussed earlier, in contrast to height and weight, which increase with age during childhood, BMI declines from infancy through early childhood and reaches its lowest point at about age BMI is reasonably well correlated with fat mass and percent body fat in heterogeneous samples of youth, but has limitations Goran et al.

Among youth aged in the Fels Longitudinal Study, age-specific correlations between BMI and components of body composition ranged from 0.

When chronological age was statistically controlled in five samples of boys and girls aged , correlations for BMI were a bit lower: percent body fat, 0.

Correlations for fat mass and fat-free mass were similar in four of the five samples, but those for BMI and percent body fat were variable.

In a nationally representative sample of American children aged in NHANES III, BMI was better than other anthropometric indicators Rohrer index and weight-for-height in predicting underweight and overweight when percent body fat or total fat mass based on DXA was the criterion measure Mei et al.

Nevertheless, youth with the same BMI can differ considerably in fat mass and percent body fat, so care is essential when interpreting BMI as an indicator of fatness in youth. BMI is, more appropriately, an indicator of heaviness and, indirectly, of adiposity; at the extremes of heaviness, BMI is probably a reasonable indicator of fatness in general population surveys, but its limitations must be recognized Pietrobelli et al.

Limited evidence supports higher intra- and interobserver reliability for BMI and waist circumference than for skinfold thicknesses Artero et al. Beyond the debate about what the measurement of BMI actually represents body composition, body fat, body weight, etc. Waist circumference is an emergent measure of body composition.

Its use as a dimension of body composition is justified for various reasons. First, it is an indicator of abdominal fat as opposed to waist-to-hip circumference ratio, which is an indicator of fat distribution Despres et al. Second, criterion measures that relate to health have already been established in certain populations of youth Liu et al.

Further, other measures are more challenging to administer, such as measuring hip circumference to determine waist-to-hip ratio WHO, Additionally, other waist measures have insufficient data to support their consideration and have not been found to be a better predictor of health risk than waist circumference Huxley et al.

On the other hand, it has been suggested that waist circumference has no advantage over BMI for diagnosing high fat mass in youth aged Reilly et al. According to a measurement protocol for adolescents, intra- and interobserver technical errors of measurement for waist circumference have been calculated at 1.

As mentioned above, a review of reliability found higher intra- and interobserver reliability for BMI and waist circumference than for skinfold thicknesses Artero et al.

Mueller and Malina report high intra- and interobserver reliabilities for waist circumferences of 0. Technical errors have also been reported in national surveys ODPHP, , Unlike other field measures, waist circumference may not be a good indicator of percent body fat or fatness in youth.

However, it is an indicator of abdominal adiposity Lee et al. Skinfolds are considered valid and reliable estimates of subcutaneous fat and predictors of percent body fat, assuming they are measured by trained individuals.

Specifically, reliability coefficients for sum of skinfolds vary by pubertal status in girls Gutin et al. Others have reported acceptable interobserver reliability coefficients of 0. The technical error of measurement for subscapular skinfold varies from 0. For triceps skinfold, the technical error of measurement ranges from 0.

The triceps and subscapular skinfolds are the most widely used in growth studies, and national reference data were developed by using the samples included for BMI in the CDC growth charts Addo and Himes, Skinfolds can be and have been measured on any number of bodily sites.

A key is standard definition and location of the sites and proper marking of the sites prior to application of the skinfold calipers.

As noted earlier, ratios of skinfolds measured on the trunk to those measured on the extremities are commonly used to estimate relative subcutaneous fat distribution, which has been related to chronic disease risk factors in youth.

When selecting fitness test items, an important criterion is the feasibility and practicality of the measures. The committee evaluated the feasibility and practicality of body composition measures assuming that they would be implemented by trained personnel as recommended in this report.

The measurements recommended for inclusion in a youth fitness test battery are height, weight, waist circumference, and triceps and subscapular skinfolds. All of these measurements can be taken reasonably quickly. The selected measurements, however, are not free of potential motivational or self-esteem influences; self-esteem may be affected by the interpretation of results for estimated body composition.

For this reason and to protect privacy, waist circumference and subscapular skinfold thickness should not be assessed in group settings. It is assumed that appropriate space e. This setting also would minimize the potential for embarrassment when two test administrators are needed in the room see below.

Equipment needed to measure body composition using the tests recommended above includes a stadiometer, a scale, skinfold calipers, and a tape measure. The NHANES measurement techniques are presented in Annex as an example of commonly used methodology for indicators of body composition.

As noted there, these anthropometric measurements, while not difficult, are highly error-prone. To avoid error, only high-quality equipment should be used, and test administrators should have the necessary technical training. This training includes proper positioning for measuring height standard erect posture with the head and eyes in the Frankfurt horizontal plane , procedures for stepping on and off the scale for example, some children may require assistance, and children must be kept from jumping on the scale , positioning for measuring waist circumference feet together , identification of the correct level for measuring waist circumference, and identification of the correct sites for measuring the triceps and subscapular skinfolds.

The level for measuring waist circumference and the sites for each skinfold measurement should be marked on the skin. Height and weight typically are measured without shoes and in light indoor clothing e.

Waist circumference is measured from the side measurements taken face-to-face are generally invasive. Two technicians may be needed to measure waist circumference in some overweight and obese youth.

This should not be a problem as a separate individual who is well versed in the measurement protocols should serve as recorder for the measurements. Other duties of the recorder include observation of the position of the subject e.

The lack of a recorder will slow down the measurement process and contribute to potential error in transcribing measurements. The committee acknowledges that there are multiple approaches to establishing cut-points cutoff scores for estimates of body composition depending on the purpose and on the available data.

In general, the committee considered the following two approaches:. The committee concludes that these two approaches are appropriate for interpretation of body composition measurements administered in the context of a national youth fitness survey.

For these approaches, a cut-point is determined specifically for each body composition test recommended. Obtaining information for the different indicators of body composition in this manner allows for a more complete and accurate description of an individual's body composition.

As a result, the interpretation of the tests in terms of health risks is expanded and possibly more accurate than if only one test is administered. A third approach, which involves transforming the raw data to a measure of percent body fat by using prediction equations, has been used for interpreting body composition test items.

This approach makes it possible to compare results from more than one measurement with a selected standard for percent body fat. This approach may be appropriate when test administrators must select one measure of body composition from multiple alternatives, such as when a battery of tests is applied in schools and other educational settings.

Cut-points for BMI have been calculated by age and gender from percentiles developed using the CDC growth charts based on data from large national surveys. The CDC growth charts are based primarily on data from the National Health Examination Survey NHES and NHANES from to NHES II and III and NHANES I, II, and III.

Sample sizes were sufficiently large in the national surveys, which were combined to produce the charts. Percentiles were derived for specific age groups by sex and were subsequently smoothed.

The recommendations have remained unchanged with the exception of overweight being used in place of risk of overweight and obesity in place of overweight Barlow and Expert Committee, The CDC developed cut-points for underweight youth based on the 5th percentile as recommended by the World Health Organization's Expert Committee on Physical Status WHO, A national survey of youth fitness in the United States should use the CDC cut-points for weight status Table An alternative set of cut-points is that developed by the International Obesity Task Force Cole et al.

Centers for Disease Control and Prevention CDC Reference Values for Body Mass Index BMI. The same U. national data used to develop growth charts for body weight and BMI were used to develop reference curves for the triceps and subscapular skinfolds for youth through age 19 Addo and Himes, The committee recommends using the established percentiles for BMI to derive interim cut-points until more studies are conducted to determine health-related cut-points in youth.

The interim cut-points could be verified using the corresponding percentiles for the concurrent relationship to health in adults. The development of cut-points for waist circumference is complicated by methodological variation, that is, different levels at which the measurement is taken in various studies.

Although the recommended level is midway between the iliac crest and the lowest rib WHO, , NHANES reference data and were based on measures taken at the uppermost lateral border of the iliac crest McDowell et al.

Corresponding reference values for Canadian youth were derived at the narrowest waist Katzmarzyk et al. Wang and colleagues found that waist circumference estimates taken at different levels on adults are not comparable, especially among females. A systematic review of the adult literature, however, found that differences in the level of measurement did not have a considerable influence on the relationship between waist circumference and health outcomes Ross et al.

Criterion-referenced cut-points for waist circumference have been established in adults WHO, Although recommendations for cut-points have been developed for different samples, generally reflecting the 90th percentile by age and gender, standardized cut-points for youth have not yet been established.

Body composition can influence performance on some physical fitness tests and is also a health-related risk factor associated with physical fitness. The committee operationally defined body composition as a component of fitness, a marker of health, and a modifier of fitness for the purposes of this report.

Given its well-known central role in both fitness and health, body composition should be included in a survey of youth fitness and measured across the life span. The committee's recommendations with respect to body composition are premised on the committee's intention that the test administrators will have the necessary knowledge and training in test protocols and interpretation of results.

The committee recommends inclusion of the following anthropometric measurements in a youth fitness test battery: 1 height and weight for the derivation of BMI, 2 waist circumference, and 3 triceps and subscapular skinfold thicknesses.

Height also serves as an indicator of linear growth status. See Annex for common examples of measurement techniques. The committee concluded that the above three measures of body composition are important to collect in a national youth fitness survey for several reasons. First, each measure is a proximal estimation of body fat and has increased standard of error of over laboratory measures.

Also, there is consensus that the measurement of body composition is multidimensional Bouchard et al. Second, no single measure is considered the gold standard and representative of all body composition tenets for children of all morphologies: BMI is a marker of obesity, waist circumference is a marker of abdominal adiposity, and skinfold thicknesses are a measure of subcutaneous fat.

The measures recommended have acceptable validity and reliability. To interpret the findings of body composition testing and determine whether individuals or populations are at risk of negative health outcomes, the committee recommends employing two approaches.

For BMI, the CDC's current established cut-points for underweight, overweight, and obesity should be applied. Interim cut-points for the waist circumference and skinfold measures should be set at levels that are analogous to those currently being applied by the CDC for BMI.

This approach should be used until the necessary evidence becomes available to support establishing waist circumference and skinfold cut-points by associating those measures with cardiometabolic risk factors. The committee's full recommendation for including body composition in a national youth fitness survey is presented in Chapter 8.

When body composition is measured in schools and other educational settings, important concerns arise related to the measurement of waist circumference and skinfolds.

Therefore, the committee recommends that only BMI be used in these settings. A full description of considerations and the committee's recommendation for schools and other educational settings is included in Chapter 9. Body composition measurements should be taken by trained individuals using established techniques.

Error—the discrepancy between a measured value and its true quantity—is inherent in anthropometry. It can be random 3 or systematic. Replicate measurements of the same subject are used to estimate variability or error.

Replicates on the same individual are taken independently by the same technician after a period of time has elapsed intraobserver or are taken on the same individual by two different technicians interobserver. Replicate measurements provide an estimate of imprecision. The technical error of measurement is a widely used measure of replicability Malina et al.

Technical errors are reported in the units of the specific measurement. Intra- and interobserver technical errors for a variety of dimensions in national surveys and several more local studies are summarized by Malina Accuracy is another aspect of the measurement process.

Note, however, that well-trained, expert anthropometrists do make errors. The height, weight, waist circumference, and triceps and subscapular skinfold measurement techniques described below are provided as examples from the commonly used NHANES Anthropometry Procedures Manual.

Stature , or standing height, is the linear distance from the floor or standing surface to the top vertex of the skull. It is measured to the nearest millimeter with the subject in standard erect posture, without shoes.

Body weight is a measure of body mass. It is measured to the nearest grams depending on the type of scale with the individual attired in ordinary, light, indoor clothing without shoes e.

It assumed that the scales would be calibrated regularly for a national survey. The protocol for waist circumference calls for measuring just above the uppermost lateral border of the right illium after normal expiration.

The level should be marked on the skin. When the tape is applied, it should make contact with the skin without indenting it. The measurement should not be made over clothing. Two individuals may be needed, especially for some overweight and obese individuals.

A skinfold thickness is a double fold of skin and underlying soft tissue at a specific site. Skinfolds are measured to the nearest 0. Three measurements usually are taken for each skinfold some protocols recommend two. Triceps skinfold is measured on the back of the arm over the triceps muscle at the level midway between the lateral border of the acromial process of the scapula acromion and the inferior border of the olecranon process of the ulna.

With the arm flexed to 90 degrees at the elbow, the acromion is marked. A measuring tape is placed on the acromion zero marker and run down the lateral side of the upper arm.

The distance midway between the acromion and the olecranon is marked and extended to the back of the arm. The skinfold is measured with the arm hanging relaxed loosely at the side by grasping a vertical fold about 1 cm above the mark, with the caliper being placed at the level of the mark.

Subscapular skinfold is measured 1 cm below the tip inferior angle of the scapula. The measurement site should be marked on the skin. The skinfold should follow the natural anatomical cleavage lines of the skin.

It is not a vertical fold like that taken over the triceps. Questions arose over which population was appropriate for establishing such percentiles related to health given concern for the increasing prevalence of obesity between NHANES II and NHANES III Kuczmarski et al.

Developing percentiles for weight using elevated values from NHANES III would have raised the percentiles and thus resulted in a false sense of having a satisfactory weight, specifically relative to stature. Data used to develop the criteria for children and adolescents were based on six nationally representative cross-sectional samples from Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States.

In establishing the cut-points for children and adolescents, curves were mathematically fit to the pooled BMI data from the six studies so that they passed through the adult criteria for overweight BMI of Cut-points recommended by the World Health Organization were used for adults: overweight, BMI Random error is associated with variation within and among individuals in measurement technique, problems with the measuring instruments e.

Random error is nondirectional, i. Random errors tend to cancel each other out in large-scale surveys and ordinarily are not a major concern. Systematic error results from the tendency of a technician or a measuring instrument to consistently under- or overmeasure a dimension.

Such error is directional and introduces bias. Measurement variability also is associated with the individual e. pdf accessed May 10, Turn recording back on. National Library of Medicine Rockville Pike Bethesda, MD Web Policies FOIA HHS Vulnerability Disclosure.

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Show details Committee on Fitness Measures and Health Outcomes in Youth; Food and Nutrition Board; Institute of Medicine; Pate R, Oria M, Pillsbury L, editors.

Contents Hardcopy Version at National Academies Press. Search term. KEY MESSAGES Body composition is a physiologic characteristic that affects an individual's ability to carry out daily tasks with vigor. For example, A high BMI is related to the risk of type 2 diabetes and hypertension.

Waist circumference is linked to risk factors for cardiovascular disease, type 2 diabetes, and all-cause mortality. Elevated skinfold thicknesses and proportionally more subcutaneous fat on the trunk are associated with an elevated risk for cardiovascular disease and metabolic syndrome.

Skinfolds provide an indication of subcutaneous fat at specifically defined measurement sites. Skinfolds can also be used to predict percent body fat. They can be expressed as a sum of skinfolds overall subcutaneous fat and as a ratio of trunk to extremity skinfolds relative subcutaneous fat distribution.

It is used internationally in public health and nutrition surveys to monitor weight status, specifically overweight and obesity. At the extremes of heaviness, BMI is probably a reasonable indicator of fatness in the general population.

Waist circumference increasingly is used as an indicator of central or abdominal adiposity rather than percent body fat, which can vary greatly among individuals with a similar BMI. Located in the abdominal region, abdominal fat is composed of three elements: visceral, retroperitoneal, and subcutaneous.

BIA provides a measure of resistance or impedance; some BIA systems are calibrated directly to fat-free mass or fat. Some other systems provide a measure of total body water that is then transformed to an estimate of fat-free mass.

The equation for converting resistance to total body weight usually includes height. Algorithms used in estimating body composition with BIA with commercially available units are considered proprietary information, which is a major shortcoming.

Given its shortcomings and the abundant evidence on the effectiveness of other field-based measures, the committee did not explore BIA further. Variation in Body Composition with Age, Gender, and Maturation Status Fat-free mass, fatness, and relative fat distribution in late childhood and adolescence approximate school ages vary with age, between genders, and among individuals of contrasting maturation status.

Fat-Free Mass The principles underlying several methods for estimating body composition warrant special consideration when applied to growing and maturing youth. Fat Mass Fat mass increases more rapidly in girls than in boys during childhood and continues to increase through adolescence in girls Malina, Weight-for-Height BMI, as a measure of weight-for-height, declines from infancy through early childhood and reaches its lowest point at about age Subcutaneous Fat A skinfold thickness is a double fold of skin and underlying soft tissues, primarily adipose tissue.

Relative Fat Distribution Fat distribution refers to regional variation in the accumulation of adipose tissue in the body. Maturity-Associated Variation Children and adolescents advanced in maturity status compared with their chronological-age peers tend to be fatter and to have proportionally more subcutaneous fat on the trunk Malina and Bouchard, ; Malina et al.

Body Composition as a Modifier of Physical Fitness Body composition is one of many factors that influence performance on laboratory- and field-based tests of physical fitness. Body Composition and Health Excessive adiposity and especially abdominal obesity have been associated with risk factors for cardiovascular disease and metabolic syndrome in youth e.

Body Mass Index BMI BMI is an indicator of weight-for-height. Waist Circumference Waist circumference is an emergent measure of body composition. Sum of Skinfolds Skinfolds are considered valid and reliable estimates of subcutaneous fat and predictors of percent body fat, assuming they are measured by trained individuals.

In general, the committee considered the following two approaches: Direct associations with health-related biomarkers —This method involves examining associations between BMI, waist circumference, or sum of skinfold scores and cardiometabolic risk factors in youth. Ideally, as discussed in Chapter 3 , data necessary to establish those associations will exist from broad populations of youth.

Indirect associations with health-related biomarkers using adult cut-points or data from other body composition measures —When the necessary data in youth are not available, associations can be examined in adult data, and cut-points established for adults can be projected to the corresponding percentile in children, if appropriate.

When data needed to establish associations between a specific test and health do not exist in youth or adults or when a cut-point exists in adults but extrapolation to youth is not appropriate i. As research progresses, cut-points based on the measure's relationship to health in youth should be developed.

Body Mass Index Cut-points for BMI have been calculated by age and gender from percentiles developed using the CDC growth charts based on data from large national surveys. Skinfolds The same U.

Waist Circumference The development of cut-points for waist circumference is complicated by methodological variation, that is, different levels at which the measurement is taken in various studies. Waist Circumference The protocol for waist circumference calls for measuring just above the uppermost lateral border of the right illium after normal expiration.

Skinfolds A skinfold thickness is a double fold of skin and underlying soft tissue at a specific site. Current status of body composition assessment in sport review and position statement on behalf of the ad hoc research working group on body composition health and performance, under the auspices of the I.

Medical Commission. Sports Medicine.