Background Information:

It is easy to divide the body into two compartments: lean tissue and fat tissue. Lean tissue is comprised of muscle, bone, skin, organs, blood, etc., while fat tissue is composed of fat. Please do not hold the stereotype that fat is ‘bad tissue to have,’ as fat has many very important roles in the body (such as cushioning, insulation, as an energy source, and as a critical component of cell membranes and nervous tissue). Don’t be fooled, however, into thinking that fat is great. Excess body fat has been linked with cardiovascular disease, strokes, adult-onset diabetes, colon cancer, arthritis, etc.

The absolute best method to determine your body com position is very final-it involves cutting you open to directly measure the amount of fat in your body. Not surprisingly, this is not considered an acceptable technique.

The ‘gold standard’ of body composition estimation is called hydrostatic weighing. It is also called underwater weighing. An individual’s dry weight is compared to their weight while submerged underwater. The closer the two weights are, the leaner a person is (since fat tissue is more buoyant than lean tissue ). Since hydrostatic weighing has numerous drawbacks (time, mathematical calculations, hygiene, etc.), it is rarely a practical alternative.

Other measurements have their advantages. The waist to hip ratio is a good indicator of cardiovascular risk, since fat stored in the abdominal area is easily mobilized, leading to coronary artery disease. The more fat that is stored in the abdominal area, the greater the waist to hip ratio.

Skinfolds are a great way to measure the subcutaneous fa t stored by the body. From skinfold measurements, a wide variety of formulas exist with which to estimate percent body fat. Be careful not to become to attached to a certain formula; each is very specific to a certain population. Rather, keeping track of the actual skinfold thickness is probably a more valuable way to measure changes in body composition.

A final note: body composition is a very sensitive issue for most individuals. You need to have maturity and sensitivity when deal ing with this issue. Be sure to keep results confidential and avoid making any judgments on your subjects.

Procedures:

Assess body composition using the following techniques:

• Weight: Measure your weight in pounds, and your height in inches. Compare to NIH Consensus Table.

• Waist to Hip Ratio: measure the circumference of the bo dy at the level of the umbilicus (the waist), and at the level of the greatest circumference around the pelvis (hips). Divide the waist score by the hip score to determine the ratio. Compare to norm charts.

Waist to Hip Ratio: __________ Category: __________

• Body Mass Index (BMI): measure your height and weight (without shoes). Be sure that measurements are done in the SI (metric) system. Calculate BMI and compare to norm charts.

BMI: __________ Category: __________

• Bioelectrical Impedance Analysis (BIA)

• record the following information: name, age (yrs), weight (kg), height (cm).
• Lie supine on the table with your shoe and sock from the right foot removed.
• Electrodes will be placed on your right wrist/hand and ankle/foot. Cables will be attached between the electrodes and the analyzer. A 50 ohm current will be passes through the body and the resistance (R) will be recorded.
• Calculate percent body fat using the equations listed with the directions, or enter data into BIA web site.

• Skinfolds: Probably the biggest problem with measuring skinfolds deals with the accuracy of the measurements made by the investigator. It is very important that the following points be observed:

• Be sure that you are pulling out a true double-thickness of skin and fat (don’t worry about pulling out muscle, it really isn’t possible. Also, be aware that it may be a little uncomfortable for the subject).
• Identify the site for the skinfold as accurately as possible.
• Place the fingers about 2 cm above or below the site. Pull the skin out.
• Place the jaws of the caliper on the middle of the skinfold (avoid being at the top or the base of the fold), and release your fingers form the calipers. Be su re to keep holding onto the skinfold!
• The calipers should be placed perpendicular to the skinfold. Avoid any ‘weird’ angles.
• After ~2 seconds, read the dial. Be sure to avoid errors of parallax.
• Open up the jaws of the calipers, and remove them from the skinfold. Don’t just slide them off (it is bad for the subject and the calipers). Release the skinfold.
• Measure each site once before measuring each site a second time; measure each site twice before taking the third measurements.

Abdomen = a vertical fold taken 2 cm lateral to the umbilicus.

Chest = a diagonal fold taken in line with the anterior axillary crease and the nipple. Should be _ of the distance from the anterior axillary crease and the nipple for men, 1/3 of the distance for women.

Midaxillary = a vertical fold taken at the intersection of lines drawn vertically form the anterior axillary crease and horizontally from the xyphoid process

Subscapular = a diagonal fold taken parallel to the inferior angle of the scapular. The inferior angle of the scapula is often found by having the subject place their right hand behind their back.

Suprailiac = a diagonal fold taken above the iliac crest, in the midaxillary line (there is usually a natural fold here).

Thigh = a vertical fold taken at the midpoint between the inguinal crease and the proximal border of the patella. Usually, having the subject stand with the right leg on a chair makes the site identification easier).

Tricep = a vertical fold taken at the midpoint of the acromion process and the olecranon process, with the arm relaxed. Often, having the arm in the ‘karate-chop’ position makes olecranon process identification easier.
 
 
 
 
 

Measurements	1	2	3	Mean
Abdominal
Chest
Midaxillary
Subscapular
Suprailiac
Thigh
Tricep

 
 
 

A final note: There are hundreds of equations to match skinfolds with body fat. Each equation is specific for a specific population. The equations we will use (Jackson & Pollock) are general equations. Choose the equation you use carefully!

Calculations (males):

7-Site Formula

Body Density = 1.112 — (.00043499)(S7) + (.00000055)(S7) ² — (.00028826) (age)

% Fat = (495/Body Density) - 450

4-Site Formula (abdomen, suprailiac, thigh, tricep)

% Fat = (.29288)(S4) — (.0005)(S4) ² + (.15845)(age) — 5.76377
 
 

3-Site Formula (abdomen, suprailiac, thigh)

% Fat = (.39287)(S3) — (.00105)(S3) ² + (.15772)(age) — 5.18845
 
 

2-Site Formula (abdomen, thigh)

*This is probably only accurate with trained athletes!

% Fat = (S2)/2< /P>
 
 

Calculations (females):

7-Site Formula

Body Density = 1.0970 — (.00046971)(S7) + (.00000056)(S7) ² — (.00012828) (age)

% Fat = (495/Body Density) - 450

4-Site Formula (abdomen, suprailiac, thigh, tricep)

% Fat = (.29669)(S4) — (.00043)(S4) ² + (.02963)(age) + 1.40 72
 
 

3-Site Formula (abdomen, suprailiac, tricep)

% Fat = (.41563)(S3) — (.00112)(S3) ² + (.03661)(age) + 4.03653
 
 

2-Site Formula (abdomen, thigh)

*This is probably only accurate with trained athletes!

% Fat = (S2)/2

Report for turn in lab:
1.  Briefly state the purpose of this experiment /laboratory session.
2.  Results: Prepare the following results section

a. In a table present the data (% Body Fat) for all students in lab of both sexes.

b. Compute the mean average for both genders. Also, calculate the range of percent body fats.

c. Make a histogram (bar chart) of the mean averages for men and women (+/- st. dev.) from our class.

d. Record all of your specific data in the spaces provided in the lab.

e. In a table, present your own percent body fat as calculated by: 4 site, and BIA and underwater weighing (if done).

3.  Discussion: (each questions should require at least one paragrpah to answer)
a.  Was there a difference in percent body fat in our class between males vs. females? If so, what was the difference and how much of a difference? Is this difference what you would expect? How does our class compare the norms for percent body fat?

b.  Was there a difference your own percent body fat using the different methods? If so how much of a difference (ie. range).
4. Application:
a.  In one well-written paragraph, apply the findings of this lab and your new knowledge of body composition techniques to your futurew career as a physical educator, exercise physiologist , coach, or fitness professional
 
 

Normative Data:

Table 1

NIH Consensus Panel Height-Weight Tables
 

Height (inches)	Weight (pounds)
	Men	Women
58		100-131
60		103-137
62	125-148	108-144
64	129-155	114-152
66	133-163	120-160
68	137-171	126-167
70	141-179	132-173
72	147-187
74	1 53-197

 

Table 2

Waist to Hip Ratio Rating Scale
 

Classification	Men	Women
High Risk	> 1.0	> 0.85
Moderate Risk	0.90 - 1.00	0.80 - 0.85
Optimal Low Risk	< 0.90	< 0.80

 

Table 3

Body Mass Index (kg/m²) Classification of Body Fatness
 

Degree of Body Fat	Men	Women
Optimal	< 25	< 27
Moderately High	25 — 30	27 - 30
High	31 — 40	31 - 40
Very High	> 40< /TD>	> 40

 

Table 4

Percent Body Fat Classifications
 

Classification	Men	Women
Lean	< 8%	< 13%
Optimal	8 — 15%	13 — 23%
Slightly Overfat	16 — 20%	24 — 27%
Fat	21 — 24%	28 — 32%
Obese	> 25%	> 33%