Lab Exam 2- Lab 7 Flashcards
being overweight or obese increases the risk of
several chronic diseases
obesity
a complex, multifactorial disease involving the interaction of physiological, metabolic, genetic, social, cultural, and behavioral factors
body composition
makeup of the body
what is the information obtained from body composition used for
risk assessment
individualization of exercise Rx
evaluating interventional progress
anthropometry
measurement of the body
what measurements are used to assess components of the body
weight, height, and waist circumference
BMI
uses height and weight measurements and is a measure of the ratio of body weight to height
BMI= body wieght (kg)/height (m2)
how many categories is BMI divided into for adults
6
under weight
normal
over weight
obese class 1
obese class II
obese class III
why is BMI not an adequate measurement of disease risk
because there is no way to determine the composition of the weight
waist circumference
assess central obesity by measuring abdominal obesity and fat distribution and provides additional information to BMI
fat located in the abdominal region (visceral fat) is associated with
a greater health risk than peripheral fat and is an independent risk predictor when BMI not markedly increased
what measurement system should be used for assessments of obesity and monitoring efficacy of weight loss programs
waist circumference
why is there so much error in assessing body composition
no direct in vivo method to measure the different components of the body
any body composition technique performed on live humans is
indirect or doubly indirect
indirect methods
derived from direct methods involving cadavers
doubly indirect methods
derived from indirect methods
as methods become further away from the direct method
there is greater error in the estimate
body composition measurements may utilize what to make estimates
prediction equations
population specific & generalizable equations
population specific equation
inaccurate if applied to individuals who differ in physical characteristics
generalizable equation
developed from diverse, heterogenous samples, and account for differences in age, gender, sex, or ethnicity
what equation does this lab use
the Siri equation
Siri equation
predicts percent body fat, a generalizable equation
individuals who are farther away from the average in physical characteristics can be
under or overestimated in terms of body fat percentage using the Siri equation
skinfold measurements
performed using a quality skinfold caliper
assess % body fat with a SEE ~3.5%
are skinfold measurements indirect or doubly indirect
doubly indirect - the equations used to predict body density from skinfolds are based on hydrostratic weighing, which is an indirect method that utilizes water displacement to estimate fat mass
skin fold measurements are based on two primary assumptions
1) subcutaneous fat is directly proportional to total fat
2) the skin fold sites selected are representative of total body subcutaneous fat
the proportion of subcutaneous to total body fat varies with
age
sex
race/ethnicity
among other factors
major limitations of skinfold analysis
technician training
applicability of equations to the individual being tested
skinfold site measurement accuracy
measurement technique
what is the SEE of skin fold measurements
3.5%
bioelectrical impedance analysis (BIA)
simple, inexpensive, quick, and non-invasive way to measure body composition
based on idea that electrical current flows at different rates through the body depending on its compositions
body is mostly composed of
water with ions, through which an electrical current can flow
what else other than water with ions does the body contain
non-conducting materials (body fat) that provide resistance to the flow of the electrical current
body fat causes what in BIA
a greater resistance (impedance) than fat-free mass and slows the rate at which the electrical current travels
DEXA
dual energy x-ray absorptiometry
uses X-ray scan to quantify the parameters of body composition
DEXA quantifies body weight into three chemical components
lean soft tissue
fat soft tissue
bone
why is the % body fat significantly higher in DEXA than anthropometric results?
because DEXA can measure subcutaneous fat, visceral fat, retroperitoneal and intramuscular fat
bone mineral density scores (BMD)
measured as SD from the mean and include a t and z score
t score
compares your bone density to the average bone density of young healthy adults of the same sex
z score
compares your bone density to the average bone density of someone your same age, sex, and race/ethnicity
the risk for bone fractures doubles with
every SD below normal in regards to BMD
what is the accepted standard for interpretations of body fat %
there are NO accepted standards for % body fat and all methods of measurement are indirect or involve error
is there a national standard for body fat %
no
is there a national standard for BMI and waist circumfrence?
yes
according to NHANES what is the recommended “health standard” for body fat percentage in both men and women
men-8-22% under 35 years old
women- 20-35% under 35years old
accuracy
how close a measured value is to the true value
precision
how close measured values are to each other
bias
whether there are systematic differences between measured and true values
athlete triad
recognized by ACSM as a syndrome of three interrelated conditions that include low energy availability, functional hypothalamic amenorrhea, or hypogonadic hypogonadism, and osteoperosis
energy availability (EA)
(dietary intake-exercise EE)/FFM
expressed in kcal/kg
the cutoff at EA at which negative health consequences occur
varies within individuals but studies where EA has been manipulated show deleterious effects with EA less than 30kcal/kg FFM/day
how many sites are used for skin fold measurements
7
body mass index is indicative of
body size
waist circumference is indicative of
body fatness
upper body obesity is aka
android - fat in abdominal area
greater health risk
lower body obesity is aka
gynoid - fat in hips and thighs
lower health risk
DEXA assessment is what type of measurement
indirect
skin fold and BIA are what type of measurement
doubly indrect
osteoporosis risk factors
ACCESS
alcohol use
corticosteroid use
calcium low
estrogen low
smoking
sedentary lifestyle
