Anthropometrics / Body composition

Question 1

What is anthropometry?

Answer 1

The science that deals with the measurement of size, weight, and proportions of the body. Examples include BMI, somatotyping, and waist/hip ratios

Question 2

What is weight bias?

Answer 2

The active or passive formation of unreasonable judgments based on a person’s weight. This can be based on false preconceived notions

Question 3

What is stigma in the context of weight?

Answer 3

The social implication carried by a person who is a victim of prejudice and weight bias.

Question 4

What are the Beliefs About Obese Persons Scale (BAOP) and the Attitudes Towards Obese Persons Scale (ATOPS)?

Answer 4

Tools used to assess one’s own potential weight bias

Question 5

What are some tools to help with assessing individuals with excess weight?

Answer 5

These include a private space for assessments, large-size gowns, sturdy armless chairs, large and extra-large blood pressure cuffs, and a wide-based scale that measures > 350 pounds

Question 6

What are some best practices when assessing individuals with excess weight?

Answer 6

Be prepared to avoid awkward moments, ensure weighing takes place in a private location, record weight without judgment, and offer the choice of not seeing the results

Question 7

When should skinfolds be avoided in an assessment?

Answer 7

If an individual has a BMI greater than 30 (classified as obese), skinfolds should not be included in the assessment

Question 8

How is height measured, and what units are used?

Answer 8

Height is measured using a stadiometer to the nearest 0.5 cm. Conversions: 1 cm = 0.394 inches, 1 inch = 2.54 cm, 1 m = 3.28 feet, 1 foot = 30.5 cm

Question 9

How is weight measured, and what units are used?

Answer 9

Weight is measured using a calibrated scale to the nearest 0.1 kg. Conversions: 1 kg = 2.20 pounds, 1 pound = 0.454 kg, 1 g = 0.035 oz, 1 oz = 28 grams.

Question 10

What is Body Mass Index (BMI)?

Answer 10

• Body mass index (BMI) is a measure of body fat based on height and weight that applies to adult men and women
• BMI is calculated as body mass (kg) / height (m²).
• It’s reasonable for health screening and large populations.
• It was originally conceived by Adolphe Quetelet

Question 11

What are the BMI classifications?

Answer 11

Normal range 18.50-24.99

Question 12

Is BMI a diagnostic tool?

Answer 12

No, BMI should be used as a screening tool, but not as a diagnostic criteria for overweight and obesity

Question 13

What is waist circumference used for?

Answer 13

Waist circumference is used to assess health risk and is adopted by CSEP and Clinical Practice Guidelines

Question 14

What is the cutoff for waist circumference?

Answer 14

Men: greater than or equal to 102 cm
Women: Greater than or equal to 88 cm

Question 15

Why are formulas to predict % body fat from circumferences not recommended?

Answer 15

Because they are regression equations based on cadaver analysis and they are not one size fits all

Question 16

What is the clinical significance of subcutaneous fat?

Answer 16

Subcutaneous fat is not as metabolically damaging

Question 17

What are Z-scores and percentiles used for?

Answer 17

Z-scores indicate how many standard deviations a value is from the mean, and percentiles represent where a value places with respect to the entire distribution. Both are useful for identifying relationship to a cohort (i.e. same age)

Question 18

What are some important considerations when measuring circumferences?

Answer 18

Careful measurement of bony landmarks, consistent technique to not compress the circumference, and frequent inspection of the tape for stretch or wear are important

Question 19

What is the focus of body composition?

Answer 19

Techniques to measure body fat and lean body mass or fat-free mass

Question 20

What are the three categories of methods for measuring body composition?

Answer 20

1. Direct (chemical or cadaver analysis),
2. Indirect (laboratory-based, e.g., hydrostatic weighing, DEXA),
3. Doubly Indirect (field-based, e.g., skinfolds, height/weight/circumference derivations)

Question 21

What is the most common compartment model in body composition?

Answer 21

The two-compartment model, which divides the body into fat and fat-free mass

Question 22

What are the assumed densities in a two-compartment model?

Answer 22

Fat has a density of 0.900 g/ml, and fat-free mass (FFM) has a density of 1.100 g/ml.
* Note FFM and LBM includes muscle, bone, organs etc

Question 23

What are multiple compartment models?

Answer 23

Models that account for a greater number of body compartments, thus reducing error. An example is DEXA, which uses a three-compartment model

Question 24

What is the principle behind hydrostatic weighing?

Answer 24

• Based on Archimedes’ Principle, which states that an object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object.
• In simpler terms, whenever something is put into a liquid, it pushes some of that liquid away. The liquid then pushes back with a force that’s exactly as heavy as the water it moved. If this force is strong enough to counteract the object’s own weight, the object will float; if not, it will sink.

Question 25

What information must be known to conduct hydrostatic weighing?

Answer 25

Residual volume (calculated based on height, age, sex), density of water (varies with temperature), trapped gas (GI approximated to be 100mL), dry body weight, and submerged body weight

Question 26

How is residual volume calculated for men?

Answer 26

RV (L) = 0.019 * height (cm) + 0.0155 * age - 2.24

Question 27

How is residual volume calculated for women?

Answer 27

RV (L) = 0.032 * height (cm) - 0.009 * age - 3.90

Question 28

What is a possible discrepancy between different formulas for calculating % body fat from body density?

Answer 28

There can be a range of variability, with a potential ( ~5% absolute; 23% relative) discrepancy in results

Question 29

What is a limitation of hydrostatic weighing related to the assumption of constant density of fat and LBM?

Answer 29

There is a possible 19% (relative) error in body fat prediction due to variability in the density of lean body mass in women.

Question 30

What is a limitation of hydrostatic weighing related to the assumption of trapped air?

Answer 30

There is a possible 8% (relative) error in body fat prediction based on variability in lung volumes alone

Question 31

What are some factors that can affect body mass determination in hydrostatic weighing?

Answer 31

Hydration/dehydration, and nutritional status can influence the calculation

Question 32

How can the accuracy of hydrostatic weighing be enhanced?

Answer 32

By doing 9-10 trials

Question 33

What is Air Displacement Plethysmography (BodPod)?

Answer 33

A method using air displacement, similar to hydrostatic weighing, but automated.

Question 34

What are some considerations for BodPod?

Answer 34

Need to minimize air displacement, but not full expiration, and population-specific equations should be considered

Question 35

What is DEXA?

Answer 35

Dual Energy X-Ray Absorptiometry, which uses a 3-compartment model (lean soft tissue, fat soft tissue, and bone) and low-level radiation to scan the whole body | DEXA is the gold standard

Question 36

What are the limitations of DEXA?

Answer 36

Relatively expensive, need technical certification, cannot be used in some populations (pregnancy), has size limitations, and metallic implants/other radiological tests may interfere

Question 37

What is Magnetic Resonance Imaging (MRI)?

Answer 37

method that also assumes a 3-compartment model and uses a high-frequency magnetic field to vibrate molecules. It can provide very fine spatial data and is considered the gold standard

Question 38

What are the limitations of MRI?

Answer 38

Very expensive, limited accessibility, and has limitations with respect to the size of individuals

Question 39

What are skinfolds?

Answer 39

A method that measures the thickness of fat folds including the skin at various anatomical sites around the body | - Doubly indirect measure

Question 40

What are the major assumptions of using skinfolds?

Answer 40

The choice of sites are representative of total body fat, and subcutaneous fat is related to total body fat.

Question 41

What are the sources of variability in skinfold measurements?

Answer 41

Type of caliper, jaw tension, landmarking of site, amount of fat pinched, time taken to read measurement, and number of sites/formula used

Question 42

How does the type of caliper affect skinfold measurements?

Answer 42

A 10% difference between Harpenden vs. Lange calipers has been reported.

Question 43

How can accuracy in skinfold measurements be enhanced?

Answer 43

By using consistent technique with respect to landmarking, amount of fat pinched, time taken to read measure, and finger pressure

Question 44

How much can % fat from skinfolds vary?

Answer 44

Approximately ± 5 %, but is usually higher

Question 45

What is a recommendation for skinfold measurements?

Answer 45

Use techniques that include upper and lower body skinfolds.

Question 46

- How are skinfold measurements used to predict body fat? - How equations for skinfolds generally work

Answer 46

The sum of skinfolds is directly entered into a formula that predicts % fat, or the sum is entered into a formula to predict body density, which can then be used to calculate % fat

Question 47

What is the validity of skinfold measurements?

Answer 47

Correlations with UWW reported as high as r = 0.92. Note it is a doubly indirect method that reduces validity

Question 48

What is the reliability of skinfold measurements?

Answer 48

Test retest reliability of r = 0.99, but dependent on technique

Question 49

When is it recommended not to perform skinfolds on the general public?

Answer 49

When BMI is over 30

Question 50

What is Bioelectrical Impedance Analysis (BIA)?

Answer 50

A non-invasive method using a low-level electrical current to measure impedance (opposition to current flow)

Question 51

How does BIA work?

Answer 51

Tissues with more water (like muscle) have less impedance, while tissues with less water (like fat) have greater impedance

Question 52

What are the pre-test guidelines for BIA? | assumptions/ pretest quidelines are questionnable

Answer 52

No eating or drinking within 4 hours, no exercise within 12 hours, must urinate within 30 minutes, no alcohol within 48 hours, no diuretic medications within 7 days, and no testing on certain days of the menstrual cycle

Question 53

What is the validity and reliability of BIA?

Answer 53

Validity is questionable; reliability can be good under controlled conditions, with varied reported range of r = 0.66-0.94. Different manufacturers use different formulas

Question 54

What is Near-Infrared Interactance?

Answer 54

A method that measures optical density of near-infrared light for the bicep of the dominant arm.

Question 55

How does Near-Infrared Interactance work?

Answer 55

Fat absorbs light, and LBM reflects light. A sensor measures the difference between light emitted and reflected back. It uses formulas with assumptions to predict % fat, but can underestimate body fat up to 10%, especially in obese clients

Question 56

What do CSEP CPT and AFLCA CFT recommend for evaluating anthropometrics?

Answer 56

BMI and waist circumference, as opposed to body composition

Question 57

What are some key considerations when selecting a measurement technique?

Answer 57

Validity and reliability of technique, application with respect to performance or health, practicality and cost, and risk

Question 58

What factors should be considered when selecting formula-based outcome measurements?

Answer 58

Population, age, sex, and if anthropometrics/body composition are dynamic based on population (children/pregnancy)

Question 59

What is important when using measurements?

Answer 59

Consider normative data availability, report variability with measurement, ensure good technique, and do not succumb to technology without research support.