Human Anthropometry class 2 notes Dr Somashekar C.pptx

human anthropology

1. ANTHROPOMETRY-2 Dr. Somashekar C MBBS, MD Assistant professor Department of Forensic Medicine and Toxicology Adichunchanagiri Institute of Medical Sciences Adichunchanagiri University B G Nagar, Nagamangala taluk, Mandya district Karnataka -571448 DATE: 17/12/2020 GOOGLE MEET LINK: https://meet.google.com/vcn-pycj-kyu

2. TOPICS Definition Anthropometric parameters Digital anthropometry Measurements of body composition Height/stature measurement technique Mass/weight measurement technique Body mass index Waist: Hip circumference ratio Child anthropometry Regression equation formula Anthropometric measurement usage in medical sciences

3. 4. MEASUREMENTS OF BODY COMPOSITION Human body can be quantified at several levels. Quantification level Assesment /measurement of At atomic level Carbon Calcium Potassium and hydrogen At molecular level Amounts of water Protein and fat At cellular level Extracellular fluid and Body cell mass At tissue level Amounts and distributions of adipose tissue Skeletal tissue and Muscular tissue

4. Methods of measurement of body composition INDIRECT METHODS Anthropometry Body mass, size, shape and level of fatness Weight, stature and Body Mass Index (BMI) Abdominal circumference Abdominal circumference (waist): Hip circumference Skin fold measurements (triceps, subscapular) Bioelectrical Impedance Analysis (BIA) DIRECT METHODS Total body water Total body counting and neutron activation CRITERION METHODS Body density Hydrodensitometry Air displacement plethysmography Dual energy X-ray Absorptiometry (DEXA) (DXA) CT & MRI

5. INDIRECT METHODS Anthropometry Anthropometric measurements are the most basic method of assessing body composition  Anthropometric measurements describe body mass, size, shape, and level of fatness. Because body size changes with weight gain, anthropometry gives the researcher or clinician an adequate assessment of the overall adiposity of an individual. Weight, Stature, and Body Mass Index (BMI) Abdominal Circumference .

6. INDIRECT METHODS Skinfolds Skinfold measurements are used to characterize subcutaneous fat thickness at various regions of the body , but it should be noted that they have limited utility in the overweight or obese adult. A few skinfold calipers take large measurements, but this is not a significant improvement because of the difficulty of grasping and holding a large skinfold while reading the caliper dial The majority of national reference data available are for skinfolds at the triceps and subscapular locations. Skinfolds are particularly useful in monitoring changes in fatness in children because of their small body size, and the majority of fat is subcutaneous even in obese children. However, the statistical relationships between skinfolds and percent or total body fat in children and adults are often not as strong as that of BMI.

7. INDIRECT METHODS BIOELECTRIC IMPEDANCE ANALYSIS The analysis of body composition by bioelectrical impedance produces estimates of total body water (TBW), fat-free mass (FFM), and fat mass by measuring the resistance of the body as a conductor to a very small alternating electrical current. Bioelectrical impedance analyzers do not measure any biological quantity or describe any biophysical model related to obesity. Rather, the impedance index, stature squared divided by resistance (S 2 /R) at a frequency [ most often 50 kHz] is proportional to the volume of total water and is an independent variable in regression equations to predict body composition.

8. DIRECT METHODS TOTAL BODY WATER Total body water is easy to measure because it does not require undressing or any real physical participation. Water is the most abundant molecule in the body, and TBW volume is measured by isotope dilution . Water maintains a relatively stable relationship to FFM; therefore, measured water/isotope-dilution volumes allow prediction of FFM and fat (i.e., body weight minus FFM) in normal weight individuals TOTAL BODY COUNTING Total body counting (also called whole body counting ) measures the amount of naturally radioactive potassium 40 (40K) in the body. Because potassium is found almost entirely within cell bodies, measuring potassium can provide an estimate of body cell mass. Fat-free mass can then be estimated once total body potassium is known, assuming a constant concentration of potassium in FFM

9. DIRECT METHODS Neutron Activation Neutron activation techniques have been reported to be highly accurate for tissue-specific body composition , with a typical body scan occupying up to 1 hour. After subject exposure to a neutron field, gamma output can be measured as the cell nucleus relaxes and goes back to its pre-exposed state. Gamma output can be measured immediately upon activation (“prompt gamma neutron activation”) or at a somewhat delayed period (“delayed gamma neutron activation”). Using this technique, many elements in the body can be measured, including carbon, nitrogen, sodium, and calcium

10. CRITERION METHODS Body density Hydrodensitometry (commonly called “underwater weighing”) is a technique that estimates body composition using measures of body weight, body volume, and residual lung volume. Air displacement plethysmography works under many of the same assumptions as hydrodensitometry and affords some advantages over it (e.g., subject compliance does not involve breath holding or aversions to being under water).

11. CRITERION METHODS Dual-Energy X-ray Absorptiometry Dual energy X-ray absorptiometry is the most popular method for quantifying fat, lean, and bone tissues. The two low-energy levels used in DXA and their differential attenuation through the body allow the discrimination of total body adipose and soft tissue, in addition to bone mineral content and bone mineral density. DXA is fast and user-friendly for the subject and the operator. A typical whole body scan takes approximately 10 to 20 minutes and exposes the subject to <5 mrem of radiation. Mathematical algorithms allow calculation of the separation components using various physical and biological models

12. CRITERION METHODS Computed Tomography and Magnetic Resonance Imaging The other imaging modalities, such as CT and MRI, are gaining in popularity and represent important new techniques for body composition assessment. CT is able to accommodate large body sizes but has high radiation exposures and, as such, is inappropriate for whole body assessments, but it has been used to measure intra-abdominal fat CT can also distinguish body tissues based on signal attenuation. This technique is especially useful for assessing nonadipose fat or the fatty infiltration of skeletal muscle or liver tissue

13. 5. HEIGHT/STATURE MEASUREMENT TECHNIQUE Stature is the standing height of an individual Also called as height vertex or body height or vertex-soles distance It measures the vertical distance from the standing floor to the vertex of the subject Vertex (v): It is the height point on the head when the head is in Frankfurt-Horizontal (FH) plane, also known as eye-ear plane. Vertex is not an anatomically fixed point and is dependent on the orientation of the head. Instrument used: Stadiometer/anthropometer

14. Now with this position of the subject set, you stand on the right side of the subject with anthropometer in the median sagittal plane of the subject and allow moving cross-bar to touch the vertex lightly. Note that the anthropometer is in vertical position. Precautions: The subject is barefoot. The heels, back and buttocks of the subject should touching the wall The toes are at an angle of 45 degrees The arms should be in standard arm hanging position The head of the subject should be in eye-ear plane The face of the subject should be stretched adjusting the mastoid process.

15. 6. MASS/WEIGHT MEASUREMENT TECHNIQUE Body weight is the most frequently used measure of obesity. Persons with high body weights typically have higher amounts of body fat. Changes in weight correspond to changes in body water, fat and/or lean tissue . Body weight should be taken by means of standard weighing machine with fine accuracy. The weight should be taken with minimum clothes and barefoot Body weight is measured in kilograms, which gives an idea of body mass Instrument used: weighing machine Method: Adjust the needle of the weighing scale to remove the zero error Ask the subject to stand with equal weight on both the feet. The head of the subject should be forward. Note the reading on the weighing scale when the needle is stationary.

16. Precautions: Take care that the subject is wearing minimum number of clothes Weight should not be taken right after taking meals Make proper adjustment for clothes worn by the subject at the time of taking weight It is recommended that at the time of recording, weight of the clothes should also be noted Jackets and shoes should not be worn in any case Spring scales are not recommended. Accurate electronic scales are available. Accuracy of the scale should be checked and calibrated regularly and frequently with a set of standard weights. Normal values: Newly born – 2.5 to 3.5 kg Adult male – 60 to70 kg Adult female – 50 to 60 kg

17. 7 . BODY MASS INDEX Also called as Quetelet Index or Kaupscher Index or Index of Bardeen-Gould- Kaup Body weight lacks specificity. This can be over come by BMI BMI is a descriptive index of body habitus that encompasses both the lean and the obese It is expressed as weight divided by stature squared BMI = Body weight (kg) / Stature (in mt)2 Normal range: 18.0 to 24.9 A significant advantage of BMI is the availability of extensive national reference data and its established relationships with levels of body fatness, morbidity, and mortality in adults.

18. BMI is particularly useful in monitoring the treatment of obesity, with a weight change of about 3.5 kg needed to produce a unit change in BMI In adults, BMI levels above 25 are associated with an increased risk of morbidity and mortality, with BMI levels of 30 and greater indicating obesity. In children, BMI is not a straightforward index because of growth. However, high BMI percentile levels based on CDC, BMI growth charts and changes in parameters of BMI curves in children are linked to significant levels of risk for adult obesity

19. 8 . WAIST: HIP CIRCUMFERENCE RATIO Abdominal circumference (AC): It is often referred to incorrectly as ‘waist’ circumference. It is measured around the abdomen at the level of umbilicus Expressed in centimeters. Obesity is commonly associated with increased amounts of intra-abdominal fat. A centralized fat pattern is associated with deposition of both intra-abdominal and subcutaneous abdominal adipose tissue. It should be noted that AC is an imperfect indicator of intra-abdominal adipose tissue, as it also includes sub-cutaneous fat deposition, as well as visceral adipose tissue. This does not preclude its usefulness as it is associated with specific health risks. Steady increase in prevalence of high AC in general population (from 10-20% in 1960s to 40-60% in 2000)

20. The ratio of AC to Hip circumference (incorrectly called as waist circumference : hip circumference ) is a rudimentary index for describing adipose tissue distribution or fat patterning. The ratio greater than 0.85 represent a centralized distribution of fat Most men with ratio greater than 1.0 and women with ratio greater than 0.85 are at increased risk for cardio-vascular disease, diabetes and cancers.

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