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13 Cards in this Set

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How else can you measure energy expenditure?
heart rate (can measure over days)
In a graph of heart rate vs. energy expenditure, what would the line look like for a trained and untrained athlete
untrained = steeper than trained
What's the problem with using heart rate to measure enery expenditure?
1) must acquire individual heart rate curves
2) curves change w/ physical conditioning (error in measurement)
What is direct calorimetry?
1) measure heat produced directly
2) VERY ACCURATE
3) Can't measure for long periods of time
4)Behaviors are restricted
5)very expensive
Why is body weight a poor indicator of stored energy in the body?
body composition is not homogeneous (don't know how much is muscle mass or storage (adipose))

-metabolic rate of muscle is greater than that of adipose
-energy density of muscle is less than that of adipose

ALSO its affected by other variables other than tissue weight (ex: water, glycogen content--heavy, insufficient energy storage)

ALSO b/c of GI contents (if you dont eat for a day, your weight goes down)
What's a typical body composition of someone weighing 150 lbs?
30 lbs muscle, 30 lbs fat, 60 lbs H20, 30 lbs bone.
One way to measure body composition is underwater densitometry (explain).
-"Archimedes principle"
-density of lean body mass is known (fat = less density so floats)
-density of fat known
-knowing total mass, you can calculate part that is fat and part that is lean
What's the problem with the underwater densitrometry method?
1) air in body b/c take a deep breathe b4 dunking (could just measure lung capasity and correct for amt of air in body)
2)Air in GI tract? anytime you eat you breathe in air
3)not convienient
BUT ITS ONE OF THE MOST ACCURATE BODY COMPOSITION MEASURES
Air densitometry is also used. Does it work?
NOT PROVEN (but water one is)
What's another way to measure body composition?
estimate body water
muscle = 70% water
adipose = 22% water
(use total body electric conductance (ToBEC)
What's the problem with using estimate of body water to measure body composition?
1)body water changes (ex. period)

the bioelectical impedence (ex: handles in gym)-measure body water but it changes

BODY IMPEDENCES HAVE LOTS OF ERROR
Is "skin calipers" good for getting an accurate measure of body composition?
based on principle that 50%-70% of body fat is subcutaneous (stored under the skin)
NOT GOOD FOR GETTING ACCURATE BODY COMPOSITION MEASURE
ALSO not valid for people less than 20 or greater than 50 yrs old OR not valid for people above 40 % fat
Name the last two ways to estimate body compostion. Which one is the best?
1) BMI: weight(kg)/height(m2)
LOTS OF ERROR: good for population studies but so inaccurate for individuals
2) Duel Energy X-ray Absorptiometer (DEXA)-tells you where the fat is deposited (can measure distribution of fat) BEST