Lab 7 Flashcards
What can body composition be used for
Risk assessment, individualization of exercise regimens, and evaluating interventional progress
What is anthropometry
Measurements of the body
What is the calculation for body mass index
Weight (kg) / height (m^2)
Is BMI an accurate measurement of disease risk
Not for all individuals because there is no way to determine the composition of the weight (e.g. in weight-training individuals)
What does waist measurement aid in
Assessing central obesity to monitor the efficacy of weight loss programs
Is visceral (abdominal) or peripheral fat associated with greater health risk
Visceral (serves as independent risk-factor when BMI isn’t really increased)
What are indirect methods to assess body composition
Derived from direct methods using cadavers
What are double indirect methods to assess body composition
Derived from indirect methods
When will a population-specific equation be innacurate
When it is applied to people who differ in physical characteristics
How are generalizable equations derived
From diverse, heterogenous samples that account for differences in age, gender, race or ethnicity, etc.
What generalizable equation does lab 7 use to predict percent body fat
The Siri equation
Body fat % = (495/bone density) - 450
What is the SEE of skinfold measurements
~3.5%
The equations used to predict bone density from skinfold measurements use what method
Hydrostatic weighing (indirect method using water displacement to estimate fat mass)
What are the 2 primary assumptions in skinfold measurements
Subcutaneous fat is directly proportional to fat and skinfold sites are representative of total body subcutaneous fat
What factors can vary the proportion of subcutaneous fat to total body fat
Age, sex, race or ethnicity, etc.
What are 4 major limitations of skinfold tests
Training of technicians, application of equations, skinfold site measurement accuracy, and measurement technique
What principle is biometric impedance analysis (BIA) based on
Electric current flows at different rates through the body depending on its composition
What effect does body fat have on current flow
It causes resistance (impedance) that slows the rate the current travels
What does DEXA stand for
Dual-energy x-ray absorptiometry
What 3 chemical components do DEXA scans separate the body into
Lean soft tissue, fat soft tissue, and bone
Why is the percentage of body fat often higher using DEXA scans than anthropometric methods
Because DEXA scans measure not just subcutaneous fat but also retroperitoneal, visceral, and intramuscular fat
What do T-scores compare bone density to
Average bone density of healthy adults of the same sex
What do Z-scores compare bone density to
Average bone density of someone your same age, sex, and race/ethnicity
How does the risk for bone fracture change with bone density
Every SD below average BD doubles the risk of bone fracture
What are the levels of bone density
Normal (+/- 1SD), low BD (1 - 2.5 SD below), osteoporosis (2.5+ SD below), and severe osteoporosis (2.5+ SD below and at least one bone fracture)
What body fat percentage is recommended by NHANES and Institue of Aerobics Research for people under 35
Females: 20-25%
Males: 8-22%
What is the athlete triad
Syndrome connecting low energy availability (with or without disordered eating), functional hypothalamic amenorrhea (females) or hypogonadotropic hypogonadism (males), and osteoporosis
What is the equation for energy availability
(Dietary intake - exercise energy expenditure) / fat free mass
EA below what values have deleterious effects
30 kcal/kg FFM/day
What are the skinfold sites for lab 7
Abdomen, triceps, chest, midaxillary, subscapula, supraillium, and thigh
*All are vertical folds except chest, subscapula, and supraillum which are diagonal
What are the current BMI standards
Underweight < 18.5
Normal 18.5 - 24.9
Overweight 25 - 29.5
Obese Class I 30-34.9
Obese Class II 35-39.9
Obese Class III >40
For non athletic, non-resistance training adults, what do they gain when they gain 1 lb
1lb of body fat
What is the difference between android (upper body) and gynoid (lower body) obesity
Android obesity is primarily in the abdominal region as opposed to gynoid obesity and poses more of a health risk because it restricts blood flow to the heart
What methods in lab 7 are indirect vs. doubly indirect
DEXA scans are indirect while skinfold and BIA methods are doubly indirect
How does body fat % change with age
Increases ~2% per decade
What is the mneumonic for risk factors for osteoporosis
A lcohol use
C orticosteroid use
C alcium low
E strogen low
S moking
S edentary lifestyle
What is amenorrhea
Absence of menstrual cycle > 90 days
What is hypogonadotropic hypogonadism
Androgen deficiency resulting in decreased libido, impaired erectile function, muscle weakenss, increased adiposity, depressed mood, and decreased vitality
