Perform body composition assessments on at least three individuals. Record all m

Question

Perform body composition assessments on at least three individuals. Record all measurements and use them to calculate body fat in pounds, total lean body mass, and the percentage of each to total body weight. Discuss the method that you used and what possible deviations could have occurred during testing. Show all measurements or readings for each individual. What are the most important factors in ensuring that you are assessing body composition accurately and consistently? How will you use body composition assessment in your future training endeavors?

Explanation / Answer

There are several methods to assess body composition such as : skinfold method, body mass index, girth measurement but most widely accepted method is hydrostatic underwater weighing. Therefore it is recommended to select 3 subjects from your institution and follow the technique which has been described below to get a result :

Hydrostatic underwater weighing measures a person's total body density using Archimedes' Principle of displacement and it is a gold standard method to assess.

Principle : It is based upon that the buoyant force on a submerged object is equal to the weight of the fluid that is displaced by the object. This method can be used to determine person's body fat percentage because the density of fat mass and fat free mass are constant. Lean tissues such as bone and muscle are denser than water and fat tissue is less denser, so muscle sinks and fat floats. Therefore a person with more body fat will weigh less underwater and be more buoyant. Someone with more muscle will weigh more underwater.

Method : To perform the test, a person is first weighed on dry land. Next, the person will get into a large tank of water. While sitting on a special scale, he is lowered underwater and asked to expel all the air from his lungs and remain motionless while the underwater weight is measured. This procedure is repeated 3 times and averaged. Then the calculation can be done by densitometry. Generally, for an adult the density of fat and fat free mass are assumed to be 0.9 g/ml and 1.1 g/ ml. If the body density is known it is possible to convert it into a % body fat using the following equation which was derived by Siri and the whole equation can be done with the help of computerized device :

% fat = (495/body density)-450

Density of the body = ( mass in air/ (( mass in air)- mass in water))÷ (density of water- residual volume)

Residual volume = volume of air in the lungs + respiratory passages after a maximum exhalation

Residual volume in inches for men = 0.033×height(inches)+0.22×age(years)-1.232

Residual volume in meters in men = 1.310×hgt(m)+0.022×age(yrs)-1.232

Residual volume in women :

Inches = 0.046×hgt(inchs)+0.016×age(yrs)-2.033

Meters = 1.812×hgt(m)+0.016×age(yrs)-2.003

By knowing the density of water it is possible to calculate the volume of water they displace and therefore determine the volume of the body.

The density of fat free mass is known to be influenced by factors like age, gender , ethnicity and little information exists in children.

Limitation is pediatric population include practical problems and theoretic considerations.The technique requires climbing into a large tank of water,exhalation of air in practical point of view which is quite cumbursome for young children and infants. Theoretically it needs additional knowledge of specific densities of fat and fat free mass of children in different state of maturity, gender and ethnicity.

Accuracy : it is consistent method and it can be used to measure progress. This method is used to judge other method's accuracy. However calculation should be correct.

Source of errors : need to get all air out the subject's lungs when weighing underwater as any air remaining will make them float and throw off the results. This is the reason that 3 underwater weights are taken so they can ensure they match.

In future body composition assessment can be used to design a work out routine tailored to a unique body composition and specific fitness and health needs.

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