APK4125 Lab 6 Body Comp

the two-compartment model

fat free mass = density of 1.1g/cm3

fat =density of 0.9g/cm3

rank the body comp assessments from most to least valid

DXA

hydrostatic weighing

BodPod

BIA

Skinfold

Ultrasound

Air Displacement Plethysmography: measurement

Volume measured by changes in pressure using Boyle's law

Volume is then used to calculate density.

Then density is used to estimate body fat using the 2-compartment model

Hydrostatic Weighing measurement

volume measured by water displacement.

Volume is then used to calculate density

bioelectrical Impedance (multi-frequency)​ measurement

total body water measured by current resistance in the body.

Then regression equation is used to estimate body fat​

skinfold testing measurement

Measurement of skinfold -> Sum of skinfolds -> estimation of body density -> estimation of body fat using 2-compartment model assumptions​

Calipers should be calibrated to what force

10 g/mm2

Skinfold Assumptions:​

1 - Skinfold is a good measure of subcutanous fat​

2 - The distribution of fat (subcutaneous vs. internal) is similar for all individuals within each sex​

3 - There is a LINEAR relationship between the sum of skinfolds and body density​

Linear relationship only for homogenous samples -> population-specific​

Assumed that roughly___ of total body fat is subcutaneous fat​

1/3

Triceps​ ​

On the posterior midline of the upper arm, halfway between the acromion and olecranon processes, with the arm held freely by to the side of the body.​

Vertical

Subscapular Measurement​

Diagonal fold (at a 45-degree angle); 1-2 cm below the inferior angle of the scapula​

Diagonal

Chest Measurement​

One-half the distance between the anterior axillary line and the nipple (men), or one-third of the distance between the anterior axillary line and the nipple (women)​

Diagonal ​

Suprailiac Measurement​

In line with the natural angle of the iliac crest taken in the anterior axillary line immediately superior to the iliac crest

Diagonal

Abdominal Measurement​

2 cm to the right of the umbilicus​

vertical

Midaxillary measurement​

On the midaxillary line at the level of the xiphoid process of the sternum ​

Vertical

Thigh measurement​

On the anterior midline of the thigh, midway between the proximal border of the patella and the inguinal crease (hip)​

Vertical

Gold-standard of skinfold measurements in the US​

Lange Metal Calipers​

Gold-standard of skinfold measurements internationally​

Harpenden Calipers​

Android

known as central adiposity. Larger amounts of fat are stored around the waist and are associated with higher risk of metabolic disorders​

Gynoid

Larger amounts of fat are distributed around the thighs and hips instead of the waist. ​

BMI formula

kg/m^2

lbs to kg

divide lbs by 2.2

inches to cm

inches x 2.54

BMI classifications

underweight: <18.5

normal: 18.5-24.9

overweight: 25-29.9

obese: >30

Low Impedance on BIA means

high lean mass​

High Impedance on BIA means

high fat mass​

high total body water (TBW) means what

good current flow (low impedance)​

low total body water (TBW) means what

poor current flow (high impedance)​

Multi-frequency BIA

These devices send out multiple frequencies in order to get a better assessment of total body water. They're also known as bioelectrical spectroscopy (BIS) devices.​

Hand-held BIA

electrodes mounted on handgrips​

Foot-to-Foot BIA

Electrodes mounted on a foot-plate​

Hand-to Foot BIA

Electrodes mounted on a foot-plate and hand grips​

BIA Client Protocol​: what you can't do

No eating or drinking within 4 hrs of test​

No mod-vigorous exercise within 12 hrs of test​

Void bladder within 30 min prior to test​

No alcohol consumption 48 hrs prior to test​

No diuretics (including coffee) prior to test​

Do not test female clients if they perceive that they are retaining water​

what is the direct body comp method

dissection

4 compartment

Protein

total body water

bone mineral content

fat mass

3 component

fat mass, lean mass, and bone mineral content

lean mass vs fat free mass

Lean mass is the sum of body water, total protein, carbohydrates, non-fat lipids and soft tissue mineral​

Fat-free mass includes everything that isn't fat. ​

DXA measurement

Density measured by high and low energy x-ray photons. This allows the break-up of 3 and 4 compartment models. But body fat can be estimated in traditional 2-compartment model ​

BMI measures or estimate body composition. ​(T or F)

False

BMI does not measure or estimate body composition. ​

Multiple research studies have shown that BMI has incorrectly labeled the body composition of up to ___% of individuals​

40