NPA: Anthropometry and Body Composition

surrogate measures of height

knee height, forearm (ulnar) length, arm span/half arm span

Frankfort plane

horizontal head position necessary for measuring height using a stadiometer

the ______ growth chart is recommended for children age 0-2

WHO

the ______ growth chart is recommended for children ages 2+

CDC

what body weight measure is most pertinent when considering an individual patient?

UBW

BMI equation

mass(kg) / ht(m) squared

BMI is also called the

Quetlet index

underweight BMI range

< 18.5

normal BMI range

18\.5-24.9

overweight BMI range

25\.0-29.9

obesity class I BMI range

30\.0-34.9

obesity class II BMI range

35\.0-39.9

extreme obesity (class III) BMI range

40\.0 +

head circumference is typically used up to age

3

where is the waist measured?

iliac crest

high risk waist circumference for m/f

m- >40in/102cm

f- >35in/88cm

desirable waist to hip ratio m/f

m-
f-

why is sagittal abdominal diameter used?

helps determine amount of visceral fat, since it does not spread out when lying down like subcutaneous fat does. more visceral fat (greater diameter) means higher risk

assumption is that ______ of body fat is subcutaneous

50%

density of lean mass vs fat mass

1\.1g/cm3; 0.9g/cm3

underwater weighing advantages

gold standard for accuracy

underwater weighing limitations

expensive and bulky equipment

participant must be trained and able to submerge

not practical for large number of participants

requires skilled technician

DXA stands for

dual-energy x-ray absorptiometry

2 uses for DXA

BMD and body composition

two types of results given in DXA

T score and Z scoreT

T score vs Z score in DXA

T compares subject BMD to that of young adult of same gender at peak bone mass

Z compares subject BMD to someone of same age and gender

DXA is a __ compartment model

3 (bone, fat, lean)

advantages of DXA

gold standard for both body comp and BMD

non-invasive- very little radiation exposure

instant results

limitations of DXA

may be up to $100-200

must remain still

exempt pop. - pregnant people, those who can’t lay down

air displacement plethysmography is used to determine body comp by

measuring body volume, which can then be used to calculate body density. use density value in equations, which depend on gender and ethnicity, to calculate est BF%

air displacement plethysmography is a ___ compartment model

two (lean mass and fat mass)

requirements for air displacement plethysmography

4hr fast

empty bladder and bowels preferred

no exercise for 4hrs

bathing suit and swim cap

advantages of air displacement plethysmography

non-invasive

limited pt effort

relatively easy

can be used in obese pop.

limitations of air displacement plethysmography

claustrophobia

specific clothing

better precision if lung vol is measured

expensive equipment

req skilled technician

bioelectrical impedance analysis (BIA) advantages

portable

low cost

non invasive

BIA is less accurate at measuring body comp in populations with

abnormal body fat distribution

advantages of skinfolds

cheap

mobile

demonstrates fat distribution

limitations of skinfolds

significant skill and practice required

must use correct equation

50% subcutaneous fat assumption may be wrong for certain pop.