Body Composition

Question 1

Compare reference man & reference woman:

Answer 1

Male:
- age: 20-24
- height: 170 cm
- weight: 70 kg
- total fat: 15%
- ESS fat: 2%
- store fat: 13%
Female:
- age: 20-24
- height: 164 cm
- weight: 57 kg
- total fat: 25%
- ESS fat: 12%
- store fat: 13%

Question 2

What are the assumptions that all us to compartmentalize the body? (4)

Answer 2

1. Densities of fat (0.9 gm/cc) & fat free body (1.1 gm/cc) are known & additive
2. Densities of fat free body relatively constant from person to person
3. Proportions of fat free body constant from person to person
4. Individual being assessed differs from reference only in amount of fat possessed

Question 3

What is Archimedes principle, how does it relate to the underwater weighing procedure, and discuss the details of how this method is used to determine body composition:

Answer 3

Archimedes Principle: a body submerged in fluid will be buoyed up by a force equal to weight of the volume displaced

Fat & FFM assessed by: densitometry
Bd = mass/volume = (BWa - BWw) - (RV + VGI) / Dw

2C method Equations:
%Fat = [(4.95/Bd) – 4.5] X 100
%Fat = [(4.57/Bd) – 4.142] X 100

Problems and increasing age:
- decreases BMC
- hydration levels

Question 4

What are the assumptions associated with the skinfold method of assessing body composition and how does skinfolds change with increasing age.

Answer 4

Practical Assumptions:
- correct anatomical sites chosen
- SF obtained from right side
- SF take correctly, not waiting too long
Theoretical Assumptions:
- total subcutaneous fat represented by selected SF sites
- Subcutaneous fat known relationship with total body fat
- redistribution of subcutaneous fat with increased age:
- fat becomes more internalized
- fat moves from periphery toward central
regions

Question 5

What are the assumptions associated with the BIA method of assessing body composition?

Answer 5

body is a cylinder of constants XSA and uniform density.

Question 6

Compare and contrast the two patterns of fat distribution.

Answer 6

Location of fat related to increased health risk
Android:
- abdominal, apple shape
more visceral fat
- Predominately male
- Beta receptors: epi easier to mobilize fat
Gynoid:
- gluteofemoral, pear shape
- more subcutaneous fat
- Predominately female
- Alpha receptors: epi difficult to mobilize fat