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Running Head: Body Composition 1

Body Composition: Assignment 2

HPR 304- B

March 3, 2018

In the following paper two body composition formulas were researched in order to help

determine body fat percentage. Before going further it is important to understand what body

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composition is. According to the book ACSM’s Health Related Physical Assessment Manual

body composition can be defined as “the study of the components of the body and their relative

proportions” (American College of Sports Medicine, 2014). The two body composition methods

were tested on two subjects; we had subject A, a female of 24 years of age, and we had subject

B, a male of 46 years of age.

In each case additional estimates were also determined for each subject; such as Resting

Metabolic Rate (RMR), BMI, fat free mass and pounds to lose based on the ACSM

recommendations for body composition. For each body composition method the following were

examined; important variables in measuring body composition, their reliability of these formulas,

and their margin of error. The two body composition formulas that were research were three site

skin-fold test and BIA (bioelectrical impedance analysis).

First the two body composition formulas will be explained along with some information

on the procedure for the two methods. The skin-fold test is an anthropometric measurement

which is used to estimate body fat percentage. For the purpose of this experiment a Lange skin-

fold caliper was used to take measurements. During the procedure a fold of skin is pinched and

using the caliper the measurement for the area is taken.

It is also part of protocol to take all measurements on the right side of the body.

Measurements are to be taken 1 cm away from the skin fold pinch; and caliper is held at skin-

fold site for a minimum of 2 seconds before reading the measurement. It is also important to

make sure that duplicate measurements are taken for each skin-fold site and that measurements

are within 1-2 mm of each other (American College of Sports Medicine, 2014). Each skin- fold

site must be marked with a pen so that measurements are taken at the same spot and more

accurate readings are taken.

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The other method we researched and tested is the bioelectrical impendence analysis

(BIA), this technique uses current to help measure fat content in the body. During the procedure

for the subject receives a small electrical current and resistance is then measured. Fat in the body

usually has very little water so it impedes the current from going through, while lean mass in the

body usually contains more water and therefore allows the current to travel more freely. For this

experiment we used an Omron BIA handheld device, the device uses its own equation and

computes the body percentage of a person.

The device had explicit conditions before taking measurements, as these could affect the

overall estimated body fat percentage. These conditions included no drinking alcohol within 48

hours, no consuming caffeine within 24 hours, no exercise 12 hours prior to testing, no eating or

drinking 2 hours before testing, and lastly testing should not be done after showering or using the

sauna. In the test a person must stand upright and hold the device with both hands, and have their

arms straight out at a 90 degree angle to the body. According to the device manual, the formula

used by this device was developed using research in hydro-densitometry. But no further

information on the formula research is given, this can be something important to consider when

thinking of measurement accuracy.

Second we will check the two method/ formulas of body composition for important

variables in measuring body composition, their reliability of these formulas, and their margin of

error. Starting first with the skin- fold method, for this test we used the 3 skin-fold sites. For the

men we used the chest, abdomen and thigh; meanwhile for women the triceps, suprailiac and

thigh. Using those sites we used the generalized formulas, each three fold site had separate

formulas for men and women. For men the following formula is used, body density = 1.10938 -

(0.0008267 x sum of three skin-folds in mm) + (0.0000016 x (sum of three skin-folds)2) -

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(0.0002574 x age). And for women the formula used is, body density = 1.0994921 - (0.0009929

x sum of three skin-folds in mm) + (0.0000023 x (sum of three skin-folds)2) - (0.0001392 x age).

The two formulas are generalized meaning they can be used on various kinds of people.

A study that compared formulas for DXA and skin- fold for body composition examined their

reliability, the study explains that the skin- fold formulas we used “were developed from non-

obese middle-aged Americans and are based on the assumption that fat is distributed

subcutaneously and internally in a similar manner for all individuals”(Chambers et al., 2014).

That assumption is problematic though because fat distribution and formulas can also vary by the

population being assessed.

The book ACSM’s Health Related Physical Assessment Manual, explains that “the

proportion of subcutaneous fat to total fat is known to vary between genders, ethnic groups, and

age” (American College of Sports Medicine, 2014). That means that the way body fat percentage

is calculated and their results can vary according to these factors. The greatest variability for

skin-fold testing is human error; the spot where the measurement is taken the way the caliper is

used affects the results. Skin- folds can also have variability in the measurements when the

caliper that’s used does not have enough force, so the quality of the tool used matters. The

formulas and technique we used is reliable to a certain degree but there are problems all these

factors can make using this method less reliable. The ACSM has stated that the standard error of

estimate or SEE for skin- fold measures is of + 3.5% (American College of Sports Medicine,

2014). However the skin- fold method is the most reliable manual method for body composition,

assuming that it was done by a trained professional.

The other method we tested which was the bioelectrical impedance analysis (BIA), for

which we used the handheld Omron device. The device uses five factors to calculate the body fat

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percentage; this includes electric resistance, height, weight, age, and gender. A study on the

accuracy of bioelectrical impedance states “BIA results are influenced by factors such as the

environment, ethnicity, phase of menstrual cycle, and underlying medical conditions” (Dehghan

and Merchant, 2008). This means that careful consideration must be taken into account when

deciding if BIA is a suitable method for determining body fat percentage. The test itself is very

sensitive to the conditions that were mentioned before, such as the rules for eating, drinking and

exercise. If any of these conditions are not met they can throw off the measurement the device

makes, this causes variability. This really comes down to human compliance of the conditions,

the health professional gives the patient rules to follow for the test.

There can also be measurement variability based on the hydration level of the person,

which is important for this test since the current introduced in the person heavily relies on water

to measure the impendence and ultimately getting a body fat percentage reading. The study on

BIA accuracy also suggests that in the majority of studies they came across, the BIA method was

not accurate when a generalized equation was used (Dehghan and Merchant, 2008). The same

study also talks about the standard error of estimate (SEE), it states that the Omron handheld

device has a SEE of + 4.5% (Dehghan and Merchant, 2008). However the overall SEE for BIA

in general according to the ACSM ranges from + 3.5% to + 5%. It is apparent then that there is

less reliability with this method and the device being used can greatly cause variability of

measurements.

Third we will go over all the calculations for each subject; we will state their body fat

percentage with each method. We will also estimate the following; Resting Metabolic Rate

(RMR), BMI, fat free mass and pounds to lose based on the ACSM recommendations for body

composition. Subject A is a 24 year old female, weighs 159 lbs and measures 63 inches. This

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subject also lives a sedentary lifestyle. Using the skin-fold method/ formula we got the body

density and then the siri equation was used to convert it to body fat percentage; subject A’s result

was 31.5 % BF.

With the BIA device and method we found that the subjects body fat percentage was

33.3%. Subject A’s BMI was calculated using her height and weight, the estimated BMI for her

is 28.23 kg/m2. The RMR was also estimated using the Harris Benedict formula, for subject A

her RMR is 1,731 kCal. Using results from the two body composition formulas the fat-free mass

was estimated for each. For skin-fold the fat free mass was 68.5%; for the BIA method the fat-

free mass was 66.7%. The ACSM reports the following on healthy body fat percentage range;

men must have between 10-22% body fat, and women can have between 20-32% body fat

(American College of Sports Medicine, 2014). Using these ranges and considering the skin- fold

method calculation as more accurate, subject A is within the range at 31.5%.

Then we tested both formulas/methods on subject B, a man of 46 years of age who is

moderately active. Subject B weighs 229 lbs and measures 5 feet 11 inches; the RMR, BMI, fat

free mass and pounds to lose were also calculated. With the skin- fold measurements and siri

formula we got subject B’s body fat; his body fat was 26.1 %. Using the BIA device we found

that subject B’s body fat was 31.5 %. Then we calculated the BMI using his weight and height,

which is 31.6 kg/m2. Using the Harris Benedict formula we found his RMR, subject B’s RMR

was 2,671 kCcal. For the skin- fold this subject’s fat free mass is 73.9%; and for BIA his fat free

mass was 68.5%. Subject appears not to be within the ACSM range for recommended body fat

percentage, therefore we will determine pounds to lose to get to a desirable range. With the

results of the skin-fold test we estimate subject B needs to lose 5% body fat to be in a desirable

range; to get to 21.1% body fat subject be must lose around 15 lbs.

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To conclude we found both formula’s with their respective methods to be reliable to a

certain degree. The reliability and accuracy depended on each case as long as conditions needed

for each method were met. Human error and compliance were key factors in affecting

measurements in both methods of body composition. It is important to acknowledge that a

formula’s accuracy depends on various factors, such as ethnicity, age and gender. Both methods

were tested on each subject and results did vary, mostly on subject B where the difference in

body fat % was greater between the two body composition methods. The reason for this could

have something to do with human error.

References

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American College of Sports Medicine. (2014). ACSMs health-related physical fitness assessment

manual (4th ed.). Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams &

Wilkins.

Chambers, A., Parise, E., McCrory, J., & Cham, R. (2014). A Comparison of Prediction

Equations for the Estimation of Body Fat Percentage in Non-obese and Obese Older

Caucasian Adults in the United States. Retrieved March 04, 2018, from

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4396823/

Dehghan, M., & Merchant, A. T. (2008). Is bioelectrical impedance accurate for use in large

epidemiological studies? Retrieved March 05, 2018, from

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2543039/