Body Composition Flashcards
1
Q
Body composition focuses on techniques to measure…
A
- body fat
- lean body mass
- fat free mass
2
Q
Direct body composition:
A
- chemical analysis
- cadaver analysis
3
Q
Indirect body composition:
A
- hydrostatic weighing
- skinfolds
- BIA
- etc.
4
Q
Body composition is the separation of ____ ____ into _____ _____.
A
- bodily tissues
- quantifiable compartments
5
Q
____ compartment model is most common.
A
2
6
Q
2 compartment model divides body into:
A
- fat vs FFM (essential
- fat removed) or lean body mass (includes essential fat)
7
Q
Nonessential fat is….
A
adipose tissue
8
Q
Essential fat is….
A
intra organ/muscle/other tissues
9
Q
FFM and LBM includes…
A
- muscle
- bone
- organs
- etc.
10
Q
Fat has a density of _____g/ml.
A
0.900 g/ml
11
Q
FFM has a density of ______ g/ml.
A
1.100 g/ml
12
Q
Why can there be error with 2 compartment model?
A
assuming fat and FFM density
13
Q
Multiple compartment models:
A
models that account for more than 2 body compartments
14
Q
The greater number of body compartments accounted for, the greater the…
A
reduction of error
15
Q
Example of multiple compartment model:
A
- Dual Energy X-ray Absorptiometry (DEXA)
- 3 compartments: fat, soft tissue, bone
- the measurement of bone density significantly reduces the error associated with amount of variation in bone density among individuals (aging)
16
Q
Hydrostatic weighing is based on _____ ____.
A
Archimedes’ Principle
17
Q
Archimedes’ Principle:
A
- any object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object
- not to be confused with the volume of fluid displaced by an object
18
Q
For hydrostatic weighing, we must know….
A
- residual volume
- density of water
- trapped gas (GI)
- dry body weight
- submerged body weight
19
Q
Residual volume is calculated based on…
A
- height
- age
- sex
20
Q
Density of water varies with _____.
A
temperature
21
Q
Trapped gas (GI) is approximated to be ____ mL.
A
100 mL
22
Q
Dry body weight is with…
A
- minimal clothing
- minimal trapped air
23
Q
Submerged body weight is with…
A
- same clothes
- minimal trapped air
24
Q
Minimum equipment required for hydrostatic or underwater weighing technique:
A
- body of water
- accurate hanging scale
- thermometer
- water density table/calculator
- may need weights to assist with submersion
- body density (BD) calculation
25
BD =
dry weight / [((dry weight - wet weight) / water density) - total gas volume]
26
Procedure for hydrostatic weighing:
- full end expiration and submersion for 5-10s
- minimize movement
- repeat 5-10 times
27
Several formulas have been derived by a variety of research to predict _____ from BD.
% body fat
28
% body fat can be used to calculate...
- fat mass (kg)
| - lean body mass (% or kg)
29
Siri (1961):
% fat = (4.95/BD) - 4.50 * 100
30
Brozek (1963):
% fat = (4.57/BD) - 4.142 * 100
31
Lohman (1986):
% fat = (5.3/BD) - 4.89 * 100
32
Limitations of hydrostatic weighing:
- assumption of the constant density of body fat and LBM
- assumption of the magnitude of trapped air: GI tract, lung, body cavity
- variability in body mass determination
- number of trials performed
33
Possible ____% (_____) error in body fat prediction is possible due to the variability in the density of ____ ____ ____ in women.
- 19% (relative)
| - LBM
34
Possible ____% (_____) error in body fat prediction based on the variability in ____ volumes alone.
- 8% (relative)
| - lung
35
How is variability in body mass determination a limitation?
in air, things such as hydration/dehydration, nutritional status can influence calculation
36
Accuracy of hydrostatic weighing is enhanced if ____ trials are done.
9-10
37
Hydrostatic weighing: if all factors are carefully controlled, repeated measurement of % fat from UW varies approx _____.
- +/- ~3%
| - range 2.5-3.8%
38
Reliability of hydrostatic weighing:
- can be good
| - test/retest r = 0.98
39
In hydrostatic weighing, there is limited ____ measurements done, so ____ is difficult.
- direct
| - validity
40
Hydrostatic weighing as an _____ measure is considered to be ____.
- indirect
| - valid
41
BodPod is aka...
air displacement plethysmography
42
BodPod uses the same theory as ____ _____, but uses ____ _____.
- hydrostatic weighing
| - air displacement
43
BodPod is _____.
automated
44
In BodPod, we need to minimize ____ _____ (...) but not full _____.
- air displacement (clothing, swim cap)
| - expiration
45
BodPod can be used in many _____.
populations
46
BodPod: Concurrent validity with UWW:
r = 0.94
47
BodPod: test-retest reliability:
r = 0.96
48
DEXA =
Dual Energy X ray Absorption
49
DEXA is a 3 compartment model:
- lean soft tissue
- fat soft tissue
- bone
50
DEXA uses a ____ type of radiation to scan the whole body, and can provide ____ data with respect to fat distribution.
- low
| - regional
51
DEXA: inter-day reliability:
r = 0.90 to 0.99
52
DEXA: concurrent validity with UW:
r = 0.90
53
DEXA: claim is that the error is less than ____% for fat.
~3%
54
Limitations of DEXA:
- relatively expensive
- need technical certification (Alberta) to operate
- due to radiation, cannot be used in some populations (pregnancy)
- can only accommodate individuals of a certain size
- metallic implants will interfere with measurements
- other radiological tests may interfere with measurements/results
55
MRI assumes a __ compartment model:
- 3
- lean soft tissue
- fat, soft tissue
- bone
56
MRI uses a high frequency ____ ____ to ____ molecules.
- magnetic field
| - vibrate
57
MRI can provide very fine ____ (____) data with respect to fat distribution.
spatial (regional)
58
____ is the most accurate determination of body composition.
MRI
59
MRI is considered by many as the new ___ ____.
gold standard
60
Limitations of MRI:
- very expensive
- limited accessibility
- limitations with respect to size of individuals (bone diameter)
61
Skinfolds measure...
the thickness of fat-folds including the skin at various sites around the body that can be anatomically land-marked
62
Skinfolds can be used as a ____ of various sites and can be used in a formula to predict ____ or ____ ____.
- sum
- % fat
- body density
63
Major assumptions of skinfolds:
- the choice of sites are representative of total body fat
| - subcutaneous fat is related to total body fat
64
Skinfolds: Equations for predicting body fat generally work 2 ways:
1. sum of skinfolds is directly entered into a formula that predicts % fat
2. sum of skinfolds is entered into a formula to predict body density, then can be used in same formulas as hydrostatic weighing for predicting % fat
65
Limitations of skinfolds:
- need consistency with respect to land-marking of site and amount of fat pinched
- time taken to read measure and finger pressure
- # of sites measured for sum or prediction of % fat formula
66
If all factors are carefully controlled: % fat from skinfolds varies approx. ___% but is usually higher.
+/- 5%
67
Skinfolds is recommended using techniques that include ____ and ____ _____ skinfolds.
upper and lower body
68
Variability in skinfolds:
type of caliper used and jaw tension
69
3 types of calipers:
- Harpenden
- Lange
- Slim guide
70
A ___% difference between Harpenden vs Lange calipers has been reported.
10%
71
Skinfods: spring load of jaw should be ___ gm/mm^2.
8-10
72
Skinfolds are a ____ ____ method.
doubly indirect
73
Are skinfolds reliable?
can be depending on technique
74
Skinfolds test retest reliability of ...
r =
75
Skinfolds are not recommended for...
- people with BMI greater than 30
| - otherwise can be used with a variety of individuals
76
BIA:
bioelectrical impedance
77
Advantages of BIA:
- easy to use
- non-invasive
- practical
- fast
78
BIA uses ...
a low level electrical current
79
BIA measures the _____.
impedance (opposition to current flow)
80
BIA: since water/electrolytes conduct ____ ____ with ____ impedance, tissues with more water (eg. ___) have _____ opposition to current flow.
- electrical current
- less
- muscle
- lower
81
BIA: the greater the resistance to current flow, the greater the....
- fat content
| - since fat has lower water/electrolyte content
82
Limitations of BIA:
- numerous assumptions many of which may be questionable
- requires strict adherence to pre-test guidelines
- validity is questionable
- reliability is varied r = 0.66-0.94
- different manufacturers use different formulas for determining % fat
83
BIA: pre-test guidelines:
- no eating or drinking within 4 hours of test
- no exercise within 12 hours
- must urinate within 30 minutes
- no alcohol within 48 hours
- no diuretic type medications within 7 days
- no testing at certain days of the menstrual cycle
- body position important, arms away from sides, legs apart/not crossed
84
Near-infrared interactance measures....
- optimal density of near-infrared light of 2 wavelengths for the bicep of the dominant arm
- at the 2 wavelengths used, fat absorbs light and LBM reflects light
85
With near-infrared interactance, a ____ measures the difference between....
- sensor
| - amount of light emitted and reflected back
86
Near-infrared interactance uses formulas that have a variety of _____ to predict % fat.
assumptions
87
Near-infrared interactance has ___estimation of body fat up to ___% and is worse in _____ clients.
- underestimation
- 10%
- obese
88
Near-infrared Interactance: _____ is questionable; ____ can be good.
- validity
| - reliability
89
Both CSEP CPT and AFLCA CFT recommend ____ and ____ to evaluate anthropometrics as opposed to _____ _____.
- BMI
- WC
- body composition
90
What factors should be consider when choosing which techniques to use?
- consider validity and reliability of technique
- application with respect to performance or health
- practicality and cost
- risk
91
Anthropometrics and body composition may be changing naturally in some populations such as...
- normal development and maturity
| - pregnancy
92
With children, _____ growth can be calculated with respect to population based _____.
- standardized
| - means
93
With children, ____ indicate how many ____ a value is from the mean.
- z-scores
| - standard deviations
94
Children: ______ represent where a values places with respect to the entire _____.
- percentiles
| - distribution
95
PHV:
- peak height velocity
| - the maximum rate of growth in stature during the growth spurt
96
PHV is determined using charting of...
- height
- sitting height
- arm span
97
PHV can be used by ____ for tracking ____ ____ of children and allows _____ of training fitness components around _____.
- coaches
- developmental age
- planning
- growth
98
Formula to predict maturity offset:
how long until (or after) a child reaches PHV
99
Age of PHV =
age + maturity offset
100
Weight by height ratio =
(weight/height) * 100
101
Pregnancy: when excess weight is gained, most of the excess will be laid down as ____ ____ and ____ ____.
- body reserves
| - heavier baby
102
Body composition is very important for ___ ____ (___) and _____ (_____).
- general population (health)
| - athlete (performance)
103
Consider _____, _____, _____ etc. if selecting formula-based outcome measurements.
- population
- age
- gender
104
Consider if anthropometrics/body comp are dynamic based on _______.
population (children/pregnancy)
105
Consider ____ data availability.
normative
106
Report ____ with measurement.
variability
107
Ensure good _____.
technique
108
Do not succumb to technology without ____ _____.
research support
