Week 7/8 Flashcards
(7 cards)
WEEK 7
Measuring Body Composition
View Cancer Research Ex - Slide 4/5
Models of body composition
- 2 compartment model:
1
2
- 3 compartment model:
1
2
3 - ## 4 compartment model–
–
1 Fat mass (adipose tissue)
2 Fat free mass (FFM) (water, muscle, bone etc)
1 Fat mass
2 FFM
3 Mineral Mass (separates bone from FFM)
– divides the body into fat, water, protein and mineral
– Avoids the assumptions that the hydration fraction of the FFM, as well as the ratio between mineral and protein in FFM, are constant
– Minor components such as glycogen and DNA are ignored
Common sites for skinfold measurements
name 5:
Single-site skinfold measurements
– A single site ______
– single site can tell you…
The triceps skinfold is ____
Steps:
- How to measure VISUAL slide 13 *
1 Triceps 2 Biceps 3 Subscapular 4 Suprailiac 5 calf
– ___ cannot ___ be used to estimate percent body fat
– … you about the composition of that site
– tricep is most common
Steps:
- Measure the triceps skinfold
- Measure the arm circumference
- Calculate the total arm area, arm fat area and the arm muscle area
Arm muscle area Vs Arm fat area VISUAL slide 14
ASSUMPTIONS
Arm muscle and arm fat areas
-
( )
-
-
-
-
- both fat and muscle areas are circular
(elderly? older you are - shape becomes less circular) - Fat symmetrically distributed throughout the body
- triceps skinfold is x2 the avg adipose tissue diameter at the middle of the upper arm
- the bone area is a constant fraction of the estimated muscle area
- cross-sectional areas of neurovascular tissue and the humerus are relative and ignored
EXAMPLE -
Calculate Total Arm Area - slide 17
Calculate Arm Muscle Area - slide 18
– To correct:
Arm Fat Area
Arm fat area = total arm area - arm muscle area (uncorrected)
- interpretation of anthro parameters - slide 23
– The basic formula overestimates arm muscle area because it includes the cross-sectional area of bone and nervous and vascular tissue
– correct: Males - subtract 10 cm²
Females - subtract 6.5 cm²
Multiple-site skinfold measurements
–> If you have skinfold measurements from multiple sites, you can use equations to:
-
-
–> There are different formulas for different populations
[ young ppl… ]
ASSUMPTIONS of skinfold thickness measurements
–>
-
-
- Calculate body density, which is used to
- Calculate percent body fat
[ppl store about one half of their body fat under the skin, as we age, a greater proportion of our body fat is stored internally]
–> The thickness of the subcutaneous adipose tissue reflects a constant proportion of the total body fat
- However, the relationship between subcutaneous and internal fat is NON-linear, and varies with body weight and age
- Lean VS obese: in fact, lean ppl have smaller proportion of total body fat deposited subcutaneously than obese ppl
–> The skinfold sites selected for measurement either singly or in combination, represents the avg thickness of the entire subcutaneous adipose tissue
- However, variations in the distribution of subcutaneous fat occur with sex, race or ethnicity and age
[Neither of these assumptions are true]
-
-
-
-
-
- look at slide 30 - if skin folds are good for Dr. *
- minimally invasive
- relatively inexpensive - only need calipers and a tape measure
- can get good estimates of body composition if done correctly
- Need training and practice to get reliable results, with low within-examiner and between-examiner errors
- Assumptions of skinfold thickness measurements are not always met
- state of hydration can affect skinfold thickness measurements
- readings can be different when using different brands of calipers
** REVIEW ALL techniques **
MRI - magnetic resonance imaging
CT scan - computed tomography
BIA - Bioelectrical impedance analysis
Total body water - isotope dilution technique
DEXA - Dual-energy X-ray absorptiometry
BodPod
Underwater weighing
Cadavers
