Illinois State University Anthropometry Chapter 5

Illinois State University Anthropometry u The measurement of the size and shape of the body. u height, u weight, u length, u breadth, u circumference, u diameter, u and skinfold thickness.

Illinois State University Anthropometry u Advantages: u Instruments are portable u Relatively inexpensive u Disadvantages: u Less accurate

Illinois State University Anthropometry u Procedures are noninvasive, and training can be provided “on the job” without prerequisite courses.

Illinois State University Anthropometry u Methods are applicable to large samples u Can provide national estimates u Provides data for the analysis of secular changes.

Illinois State University Anthropometry Assumption: u the tissues included in the measurement are in a “standard” state, u for example, that muscles are relaxed and that soft tissues are normally hydrated.

Illinois State University Anthropometry u If these conditions are not met, the interpretation may be invalid.

Illinois State University Height and Weight Measures

Illinois State University Height and Weight u Initial attempts to gauge the relationship between body type and health relied on measures of height and weight. u Driven by the life insurance industry.

Illinois State University Body Mass Index

Illinois State University Body Mass Index u BMI is determined by measuring your weight in kilograms and dividing it by your height in meters 2 u This allows for comparisons of “stoutness”, not body composition.

Illinois State University BMI u Used to classify individuals at risk for obesity-related diseases, and to monitor changes in body fatness of clinical populations.

Illinois State University BMI u BMI is a significant predictor of cardiovascular diseases and type 2 diabetes.

Illinois State University BMI u BMI is widely used in population-based and prospective studies to identify at- risk individuals.

Illinois State University BMI u However, BMI is limited as an index of obesity (i.e., body fatness) because it does not take into account the composition of an individual’s body weight.

Illinois State University BMI u In addition, factors such as age, ethnicity, body build, and frame size affect the relationship between BMI and %BF.

Illinois State University BMI u Using BMI as an index of obesity may result in misclassifications of underweight, overweight, and obesity. u It is also not a preferred method of assessing fat distribution.

Illinois State University Overweight and Obesity (BMI) III> 40 II I Obesity Overweight Normal Wt <18.5Underweight Obesity ClassBMI (kg/m 2 ) WHO 1998

Illinois State University Lengths and Breadths

Illinois State University Anthropometry u Lengths and breadths are interpreted as skeletal dimensions because they are made between bony landmarks. u Table 5.2, p 71 contains information on commonly measured sites.

Illinois State University Lengths and Breadths u The effects of soft tissues on recorded lengths and breadths can be reduced and made less variable by the use of recommended calipers and the application of firm pressure.

Illinois State University Circumferences

Circumferences u Limb and trunk circumferences are measured with a tape measure while minimal tension is applied so that the soft tissues will not be compressed; therefore enlargement of muscle and SAT due to edema increases the recorded measurements.

Illinois State University Circumferences u Figure 5.1, p. 72 shows the locations of common circumference measures. u Table 5.1, on pp describes how these measures should be taken.

Illinois State University Circumferences u Circumferences of the limbs are difficult to interpret because they include skin, SAT, muscle, bone, blood vessels, nerves, and small amounts of deep adipose tissue (DAT).

Illinois State University Circumferences u It is even harder to interpret trunk circumferences, which include organs in addition to various tissues.

Illinois State University Circumferences u Interpretation of buttocks (hip) circumference is uncertain because it includes large amounts of adipose tissue and muscle and it is affected by pelvic size and shape.

Illinois State University Circumferences u Even standing for 1-2 hrs., or prolonged sitting, causes an accumulation of extracellular fluid in the lower limbs leading to increases in ankle and calf circumferences.

Illinois State University

Circumferences u Abdominal circumferences are correlated with body density (r = -0.7), and the correlation of limb circumferences with body density are about -0.4.

Illinois State University Circumferences u The correlation of abdominal and limb circumferences with FFM are about 0.6 in each gender.

Illinois State University Waist to Hip Ratio

Illinois State University Waist to Hip Ratio u The WHR is commonly used as an indirect measure of lower and upper body fat distribution. u Figure 5.4, p. 74 (pdf file) illustrates how these measures are made.

Illinois State University WHR u Upper body or central adiposity, measured by the WHR, is moderately related (r = 0.48 to 0.61) to risk factors associated with cardiovascular and metabolic diseases in men and women.

Illinois State University WHR u Young adults with WHR values in excess of 0.94 for men and 0.82 for women are at high risk for adverse health consequences.

Illinois State University WHR u Limitations: u In women, it is affected by menopausal status. u Not valid for evaluating fat distribution in prepubertal children. u The accuracy of assessing VAT decreases with increasing levels of fitness.

Illinois State University WHR Limitations u And finally: u Hip circumference is influenced by subcutaneous fat deposition only, whereas waist circumference is affected by both VAT and SAT. u Thus, the WHR may not accurately detect changes in VAT.

Illinois State University WHR u Table 5.4, p. 78 (pdf file) contains norms for waist-to-hip circumference ratios for men and women.

Illinois State University Waist Circumference

Illinois State University Waist Circumference u WC is gaining support as an alternative to WHR for assessing regional adiposity in field and clinical settings.

Illinois State University WC u Compared to the WHR, WC provides a more accurate indirect measure of visceral fat and is not greatly influenced by age, gender, standing height, and degree of overall adiposity.

Illinois State University WC u WC is highly related (r = 0.76 to 0.88) to MRI and CT measures of intra- abdominal (visceral) fat in men and women, and to cardiovascular risk factors in older (67-78 yrs) women.

Illinois State University WC u The National Cholesterol Education Program (2001) recommends using WC cutoff values of > 102 cm (40 in) for men and > 88 cm (34.6 in) for women to evaluate obesity as a risk factor for coronary heart disease and metabolic disease.

Illinois State University Anthropometry u Anthropometry, when used in relation to body composition, is based on the assumption that the tissue composition is independent of tissue size.

Illinois State University Anthropometry u This assumption may be violated. u For example, the fat content of adipose tissue is positively related to SAT thicknesses within age groups and the fat content becomes larger as SAT thicknesses increase during growth.

Illinois State University Anthropometry u The choice of anthropometric measures, and the procedures used, differ for some groups.

Illinois State University Anthropometry u For example, the precise measurement of infants and preschool children requires that they be content; one cannot obtain precise measurements of hungry or thirsty children.

Illinois State University Anthropometry u Precise refers to repeatability judged from inter- or intraobserver differences, and the term validity refers to comparisons between observed measures and the true values.

Illinois State University Anthropometry u Disabled and elderly subjects who cannot stand erect must be measured recumbent to obtain precise and valid data.

Illinois State University Anthropometry u The utility and interpretation of anthropometric variables are related to their short-term variations.

Illinois State University Anthropometry u There is a loss of stature and an increase in abdominal and calf circumferences with prolonged standing, and there is considerable day-to-day variability of weight due mainly to the intake and elimination of food and water.

Illinois State University Anthropometry u These fluctuations in weight reflect alterations in extracellular water but are not otherwise related to changes in body composition.

Illinois State University Anthropometry u Because of these short-term fluctuations, it is recommended that relationships between anthropometric variables and body composition be determined from data recorded in the morning from fasting subjects after they have eliminated.

Illinois State University Anthropometry u It is also recommended that data not be collected in the week before a menstrual period or during a menstrual period, when there may be an increase in the fluid content of the fat-free mass.

Illinois State University Anthropometry u Knee height can be used to predict stature in those who are unable to assume the standard position for the measurement of stature.

Illinois State University Anthropometry u Alternatively, arm span, which is also little affected by aging, can be used in place of stature for elderly individuals who are unable to stand.

Illinois State University Anthropometry u Abdominal depth is of interest because it is related to the amount of deep abdominal adipose tissue.

Illinois State University Anthropometry u In the discussion of the relationships between anthropometric variables and total body composition, some of the anthropometric variables are referred to as “indices” because they can be used to categorize individuals (e.g., lean, obese), but, they do not provide metric values for aspects of body composition.

Illinois State University Anthropometry u Some variables that are indices of total body composition are actually measures of regional body composition.

Illinois State University Anthropometry u All reported relationships between anthropometric variables and total body composition understate the actual relationships because neither the anthropometric variables nor the body composition variables are measured with exact precision.

Illinois State University Anthropometry u The total body composition variables considered here are percent fat (% BF), fat-free mass (FFM), total body muscle, and total body bone mineral (TBBM).

Illinois State University Anthropometry u Some prefer body density to % BF as the dependent variable in predictive equations because the relationships with anthropometric values are not affected by the uncertain calculation of % BF or FFM from body density.

Illinois State University Anthropometry u After body density has been predicted, a body composition variable is calculated from it and these calculations are based on assumptions that may be inaccurate.

Illinois State University Anthropometry and Fat-free Mass u Stature is not an effective predictor of FFM when used alone.

Illinois State University Anthropometry and Fat-free Mass u Skeletal lengths and breadths have only low correlations with % BF, but breadths have a correlation with FFM of about 0.6 that are reduced to about 0.3 when the effects of stature are removed.

Illinois State University Anthropometry u The term RMSE is used instead of the standard error of the estimate to summarize the differences between observed and predicted values. u These terms are mathematically the same.

Illinois State University Anthropometry u BMI values are moderately correlated with % BF (r about 0.6 to 0.8), but the RSME of the prediction of % BF from BMI is about 3.5 to 5% BF.

Illinois State University Anthropometry u Despite these errors, BMI has high specificity (recognition of true negatives) in screening for high % BF values.

Illinois State University Anthropometry u Predictive equations should be applied only after they have been successfully cross-validated for a population similar to the one that will be studied.

Illinois State University Anthropometry u While some anthropometric predictive equations have been successfully cross- validated, they may not perform well in all other groups.

Illinois State University Anthropometry u There is no advantage in predicting FFM in preference to % BF since a predicted value for either can be used to calculate the other.

Illinois State University Anthropometry u Nevertheless, it is logical to predict FFM if BIA, circumferences, breadths, and lengths have been measured and to predict % BF if skinfold thicknesses dominate among the predictor variables.

Illinois State University Anthropometry u In judging equations to predict FFM, it should be recalled that the error in FFM values from body density is about 1.9 kg for men and 1.5 kg for women.

Illinois State University Anthropometry u The PE of anthropometric equations to predict FFM are about 1.2 kg in boys and 3.0 kg in young adults.

Illinois State University Anthropometry u There is a lack of equations to predict total muscle mass because it is difficult to measure the dependent variable.

Illinois State University Anthropometry u The only methods for the measurement of total muscle mass in the living are serial whole-body CT or MRI scans, which are not applicable to large samples.

Illinois State University Anthropometry u Indices of muscle mass from creatine excretion, labeled creatine, or the potassium/nitrogen ratio are too uncertain to be used as the dependent variable.

Illinois State University Anthropometry u Total body bone mineral (TBBM, g) affects body density and, therefore, it is included in four-component models based on density.

Illinois State University Anthropometry u TBBM, which is usually measured by DEXA, is the sum of the osseous and non-osseous mineral, but the latter is a small near-constant proportion of the total mineral.

Illinois State University Anthropometry u Anthropometric values, in combination with age, gender, and ethnicity, may be useful in predicting TBBM.

Illinois State University Anthropometry u During infancy and childhood, TBBM is highly correlated with weight and stature (r = 0.9), but the corresponding correlations in adulthood are only moderate ( r= 0.3 to 0.7).

Illinois State University Frame Size

Illinois State University Frame Size u Skeletal dimensions are used to classify frame size. u The rationale for measuring frame size is that skeletal breadths are important estimators of the bone and muscle components of FFM.

Illinois State University Frame Size u The best estimators of frame size are those that are highly related to FFM (independent of stature) and poorly related to FM. u The wrist, ankle, and elbow breadths are valid measures of frame size.

Illinois State University Frame Size u Table 5.5, p. 80 shows how measures of elbow breadth can be used to estimate frame size.

Illinois State University Anthropometry u There are considerable errors in all body composition measures; u these errors may be larger in the obese u and they are necessarily larger for predicted values than for observed values.

Illinois State University Anthropometry u Therefore, anthropometry is unlikely to provide accurate measures of changes in body composition.

Illinois State University Anthropometry u Efforts to estimate the changes in body composition with weight loss in the obese should be based on equations that use circumferences rather than skinfold thicknesses because the changes in circumferences are larger, with the possible exception of subscapular skinfold thickness.

Illinois State University Anthropometry u Adipose tissue distribution will be used in reference to the absolute and relative amounts of adipose tissue in body regions.

Illinois State University Anthropometry u The term fat patterns, which is in common use, is misleading since it usually refers to adipose tissue distribution. u Fat is a chemical term u Adipose tissue contains more than fat (lipid)

Illinois State University Anthropometry u Further research is needed to establish the best anthropometric description of SAT distribution taking into account relationships with risk factors for selected cardiovascular and metabolic diseases and the functional characteristics of adipocytes at different locations.

Illinois State University Anthropometry u DAT areas are markedly larger in the elderly than in young adults at the same BMI.