Body Composition

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Body Composition
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Body Composition

• Definition describes the percentages of fat,
  bone, muscle, and fluid that make up body weight.
• Because muscular tissue takes up less space in
  our body than fat tissue, our body composition,
  as well as our weight, determines leanness.
• Factors that affect a persons body composition
  may include heredity, diet, exercise, occupation.

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Two people at the same height and same body
weight may look completely different from each
other because they have a different body
composition.
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Male and Female

• The National Institute of Health recommends that
  a healthy adult male's body should have between
  13 and 17 percent fat.
• A healthy female's body should be composed of
  between 20 and 25 percent fat.
• FITNESSGRAM suggest that there is an optimal
  range within the HFZ. Ideally, students should
  strive to be within the optimal range, which is
  10 to 20 fat for boys, and 15 to 25 fat for
  girls.
• Why is the FitnessGram different than that of an
  adult? Answer kids are still growing.
• Levels significantly above these amounts may
  indicate excess body fat.

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Body composition (particularly body fat
percentage) can be measured in several ways.

• Skinfold measures
• Bioelectrical Impedance
• Underwater Weighing
• Body Mass Index (BMI)

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Skinfold Measurement

• Description This method is the most widely used
  body composition testing method for assessing
  percent body fat. Equipment used for this
  assessment includes a skinfold caliper. A
  Skinfold Caliper is designed specifically for
  simple accurate measurement of subcutaneous
  tissue. Either a 7 or 3 site skinfold may be
  assessed.

7 site skinfold chest triceps subscapular axilla suprailiac abdomen thigh 3 site skinfold (Men) chest abdomen thigh
3 Site Skinfold (Women) tricep suprailiac thigh How accurate is it? If each test is performed correctly according to the recommended guidelines, there is a /- 3 error
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Advantages and Disadvantages

• Disadvantages
• Technical sources of error
• Mostly concerned with subcutaneous fat (under the
  skin)
• May not be an ideal measurement for those who are
  obese and very lean

• Advantages
• Easy to use once skill has been mastered
• Does not require much time
• Noninvasive method
• Inexpensive way of estimating percent body fat

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Bioelectric Impedance

• Description By standing barefoot on metal foot
  plates, an undetectably low voltage electric
  current is sent up one leg and down the other.
  Since fat is a very poor conductor of
  electricity, a lot of fat will impede the current
  more so than a lot of lean tissue. By measuring
  the resistance to the current, the machine
  estimates the percent body fat.

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Advantages vs. Disadvantages

• Advantages
• Requires little or no technical knowledge of the
  operator or the client
• Testing itself takes less than a minute
• The unit can be easily transported from place to
  place
• Requires only an electrical outlet and the
  machine itself

• Disadvantages
• This method has a higher standard error range
  than most people desire
• Tends to consistently overestimate lean people
  and underestimate obese people

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Underwater WeighingA.K.A. Hydrostatic Weighing

• Description This method uses Archimedes
  principle which states that when a body is
  submerged in water, there is a buoyant counter
  force equal to the weight of the water which is
  displaced. Because bone and muscle are more dense
  than water, a person with a larger percentage of
  fat free mass will weigh more in the water and
  have a lower percent body fat. Conversely, fat
  floats. Therefore, a large amount of fat mass
  will make the body lighter in the water and have
  a higher percent body fat.

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How accurate is it? If each test is performed
correctly according to the recommended
guidelines, there is a /- 1.5 error. (Note
Accuracy depends on the clients ability to blow
all the air out of their lungs both during a
pre-test screening with a spirometer, and during
the test itself. Since air makes the body float,
inability to perform either of these maneuvers
will result in miscalculation of the percent body
fat.)

• Advantages
• This method is currently considered the "gold
  standard" in percent body fat measurement
• Repeat measures usually prove consistent, and can
  be used to chart progress

• Disadvantages
• This method usually requires a lot of equipment
  and space
• Testing is time consuming and involved
• Requires in-depth knowledge to administer the
  tests and compute the calculations
• Being submerged under water may be difficult and
  produce anxiety for some

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Body Mass Index (BMI)

• Provides an indication of the appropriateness of
  a childs weight relative to height.
• Body mass index is determined by the following
  formula weight (kg) / height squared (m)
• Example a student weighing 100lbs (45.36
  kilograms) who is 5 feet (1.52 meters) tall would
  have a BMI of 19.6. Another student of the same
  weight but 5 feet 2 inches tall would have a BMI
  of 18.3.

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BMI

• Advantage
• Fast
• Does not require much skill
• Procedure is less invasive than skinfold testing
  and may be better accepted in some districts.

• Disadvantage
• Estimates based on height and weight such as BMI
  result in 5 to 6 error because body weight
  reflects muscle and bone mass and not just fat
  mass.
• Body mass index is not the recommended procedure
  for determining body composition because it does
  not estimate the percent of fat.
• It merely provides information on the
  appropriateness of the weight relative to the
  height.

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Good Body Composition

• Decrease levels of body fat that cause obesity
• Decrease risk of coronary heart disease
• Decrease chances for stroke
• Decrease chances for diabetes
• Lower blood pressure
• Lower Cholesterol levels

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Lifetime

• Like other dimensions of health-related fitness,
  body composition does affect health status (even
  in childhood) and does improve with regular
  participation in physical activity and diet.