Slide 5 - Hydrostatic

Question 1

What Densitometry measure

Answer 1

Measurement of body density

Db = body mass/body volume

Question 2

How is body volume measured

Answer 2

Hydrodensitometry

Air displacement

Question 3

What is hydrodensitometry

What do we measure air displacement with

Answer 3

Underwater weighing

BodPod

Question 4

How is % body fat calculated using these methods

Answer 4

Calculated from Db using equations

Question 5

Hydropdensitometry has been used for

It measures

What is the principle based off

Answer 5

Decades in fitness facilities and research

mass per unit volume of persons body

Archimedes principle

Question 6

What is archimedes principle

Answer 6

The buoyant force is equal to the weight of the displaced water

Loss of weight under water is directly proportional to the volume and weight of the water displaced by the body

Question 7

Volume of an object submerged in water equals

Answer 7

The volume of water displaced by the object

Question 8

The loss of weight under water is directly proportional to

Answer 8

The volume and weight of the water displaced by the body

Question 9

Object submerged in water is acted on by

That is equal to

Answer 9

A buuoyancy force

The weight of water displaced by the object

Question 10

Mass displaced =

Answer 10

Weight (air) - Weight(water)

Question 11

Volume =

2 equations

Answer 11

Loss of weight in water / density of water

Or

Weight (air) - weight (water) / density of water

Question 12

Db =

Answer 12

Total body weight in AIR / volume

Question 13

When does the forumla work

What do we therefore have to additional corrections

Answer 13

When the object has no hollow spaces

Lungs and other trapped air spaces in body

Question 14

What is residual lung volume

Answer 14

Air trapped in lungs after maximal expiration

Question 15

Can we directly measure residual volume

Answer 15

NO

Can estimate based on sex, height and age

Or on % of vital capacity

Question 16

How much approx is residual volume

What is the deviation in % body fat when using ESTIMATED RV

Answer 16

1 - 2 litres

1 - 4%

Question 17

Is gastrointestinal gas larger or smaller than RV

What is it assumed to be

Answer 17

Smaller amount

100ml

Question 18

How do you control gastrointestinal gas

Answer 18

With pre test diet

Avoid gas producing food or soda

Question 19

What is the additional correction for working out:

Db =

Answer 19

Body weight in air
______________
((Weight in air - weight in water) / Density) - (RV + 0.1L)

Question 20

What are the assumptions made when doing hydrodensitometry

Answer 20

Separate densities of body compnents are additive

Densities of components are relatively constant from person to person
e.g. Density of fat = 0.9007 and FFM = 1.1000

Two component model:
Proportions of components in FFM are relatively constant from person to person
e.g. 73.8% water, 6.8% mineral, 19.4% protein

Question 21

What is the validity of hydrostatic weighing

Answer 21

Chemically determined body density agrees within 0.6% with Db

Question 22

What are the sources of error in hyrdrostatic weighing

Answer 22

Getting an accurate underwater weight

Value used for density of FFDb

Residual volume estimated

Question 23

Hydrodensitometry is based on what principle

Answer 23

Archimedes

Question 24

Body density is calculated by total body weight in air divided by body volume

Answer 24

True

Question 25

Residual lung volume is approximately 0.1L

Answer 25

False

Question 26

To correctly calculate the body volume, both the amount of water that is displaced and the density of water should be considered

Answer 26

True

Question 27

Hydrodensitometry follows a 3 component model assuming that the proportions of components in fat free mass are relatively constant from person to person

Answer 27

False

Question 28

A 30 year old women with body weight of 68 kg and height of 5’5’’ went through hydrostatic weighting assessment. The water temperature in the tank was 32 degree Celsius. What is the density of water

Answer 28

0.9951

Question 29

A 30 year old women with body weight of 68 kg and height of 5’5’’ went through hydrostatic weighting assessment. The water temperature in the tank was 32 degree Celsius. What is the estimated residual volume

Answer 29

1.467

Question 30

A 30 year old women with body weight of 68 kg and height of 5’5’’ went through hydrostatic weighting assessment. The water temperature in the tank was 32 degree Celsius. The density of water is 0.9951. What is her body density if her underwater weight was 1.0 and what is her % body fat

Answer 30

1.03589 28%

Question 31

A 30 year old women with body weight of 68 kg and height of 5’5’’ went through hydrostatic weighting assessment. The water temperature in the tank was 32 degree Celsius. Her % body fat was 28%. She wants to go through exercise training and lose weight. What is her desired body weight if she wants 20% body fat assuming that she wants to keep same amount of lean body mass

Answer 31

61.2kg

Question 32

A 30 year old women with body weight of 68 kg and height of 5’5’’ went through hydrostatic weighting assessment. The water temperature in the tank was 32 degree Celsius. She wants to go through exercise training and lose weight. Her desired body weight is 61.2kg. How much does she need to lose weight

Answer 32

6.8 kg

Question 33

One of the assumptions of hydrostatic weighing method for body composition assessment is that densities of components are relatively constant from person to person

Answer 33

True

Question 34

If underwater weight is measured higher that what it is, body density will be calculated higher and % body fat will be estimated higher

Answer 34

False

Question 35

If you are a trained (strength and resistance-based exercise training) individual, using Siri equation after hydrostatic weighing method to estimate % body fat may result higher value

Answer 35

True

Question 36

To evaluate _______ of the test, you will have another person measure on the same client

Answer 36

Objectivity

Question 37

What describes the amount air trapped in lungs after a maximal expiration

Answer 37

Residual volume

Question 38

The assumed amount of gas trapped in the gastrointestinal system when you use hydrostatic weighing method to assess body composition is approximately

Answer 38

0.1L

Question 39

Which method will you report the best represent your body composition

Answer 39

DXA

Question 40

Is hydrostatic weighing a more valid method than the skinfolds method.

Answer 40

True

Question 41

How do you calculate desired body weight using LBM

Answer 41

Actual LBM / desired % LBM

Question 42

How do you calculate RV for male and female

Answer 42

Male = 0.033 (ht inch) + 0.022(age) - 1.232 Female = 0.046 (ht inch) + 0.016(age) - 2.003

Question 43

How do you work out FM

Answer 43

Body fat % x BW

Question 44

How do you work out LBM

Answer 44

BW - FM

Question 45

What is the equation for SIRI What is the equation for Brozek

Answer 45

((4.950 / body density) - 4.5) x 100 ((4.570 / body density) - 4.142) x 100