Body density measurement techniques -
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Boston, Allyn and Bacon, , 2nd edition. Download references. You can also search for this author in PubMed Google Scholar. Institute for Aerobics Research, Dallas, Texas, USA. Jean Storlie M. Research Associate Research Associate.
Institute for Behavioral Education King of Prussia, Pennsylvania, USA. Henry A. Jordan M. Director Director. Reprints and permissions. Practical Methods of Measuring Body Composition.
In: Storlie, J. eds Evaluation and Treatment of Obesity. Sports Medicine and Health Science. Springer, Dordrecht. Publisher Name : Springer, Dordrecht. Print ISBN : Use our testing guide to conducting, recording, and interpreting fitness tests.
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home search sitemap store. newsletter facebook X twitter. The Body Mass Index The body mass index BMI is only a first step in the assessment of body composition, but it goes beyond the simple measurement of total body weight.
converts 1 to The formula for BMI thus becomes However, in both cases, the BMI is essentially In , the World Health Organization WHO used the BMI to define obesity in adults [ 2 ].
In , the WHO also defined categories of risk based primarily on premature mortality for any given BMI [ 3 ]. These divisions are shown in Table The criteria apply to both women and men. An example is shown in Fig. Obesity: preventing and managing the global epidemic.
Report of a WHO consultation on obesity. Geneva, WHO, , p9 Fig. Although the BMI is an improvement over the assessment of weight alone, it does not address the actual percentage of total body fat or the distribution of fat in the body.
The BMI obviously cannot distinguish the contribution to weight from either lean or fat tissue. As a consequence, individuals with a large muscle mass may actually have a BMI that results in a classification of overweight or obese, when clearly they are not.
More sophisticated methods for body composition are required to quantify the percentages of fat and lean tissue and the distribution of each within the body. Body Composition Methods The body can be divided into two major compartments: fat and fat-free.
The fat-free compartment can be further divided into water, protein, and mineral. The various techniques used to measure body composition are characterized by the number of compartments that they measure. A 2-compartment method measures fat and fat-free mass. If a method is described as a 3- or 4-compartment method, it is measuring fat mass and 2 or 3 of the components of the fat-free mass, respectively.
Near-infrared interactance NIR and DXA body composition assessments are 3-compartment methods. The principle behind UWW is that there is an inverse relationship between body fat and body density.
That is, as one goes up, the other goes down. The major assumption in UWW is that the densities of the fat and fat-free mass in the body are constant [ 4 ].
It is generally agreed that fat mass has a density of 0. In the past, the density of the fat-free mass was assumed to be a relatively constant 1. This does not appear to be true. Recall that the fat-free mass consists of water, protein, and bone mineral. Variations in any of these components may cause the density of the fat-free mass to change.
Although the bone mineral is a small percentage of the fat-free mass, it contributes significantly to the density of the fat-free mass. As a consequence, changes in the amount of bone mineral have a greater influence on the total density of the fat-free mass than might otherwise be expected.
This creates potential inaccuracies in the measurement of total body fat with UWW in which the amount of bone mineral is assumed, rather than measured. If the density of the fat-free mass is lower because of a decreased total body bone mineral content, the total body percent fat will be overestimated by UWW [ 5 ].
The converse is also true; if the density of the fat-free mass is higher because the total body bone mineral is greater than assumed, UWW will underestimate total body percent fat. The technique calls for the complete submersion of the individual in a tank of water.
The individual is asked to exhale as much as possible, and then, while holding their breath, they are submerged and weighed underwater. Under ideal circumstances, no clothing of any kind is allowed for the measurement. This requirement is often waived, but this will affect the accuracy of the measurement to a small extent as well.
The amount of air left in the lungs after completely exhaling, the residual lung volume, must be measured since this is expected to provide some buoyancy to the body while underwater. In some institutions, the residual lung volume is estimated, rather than measured, using equations that are specific for age, height, and gender.
Consequently, the weight of the body underwater reflects the weight of the body minus the weight of the fluid that is displaced by the volume of the body.
When combined with knowledge of the residual lung volume, the volume and density of the body can be estimated. The classic equation used to calculate the density of the fat mass from the total body density is the equation from Siri [ 6 ] in which In recent years, however, equations have been developed for the calculation of fat density that is age and gender specific.
and Lori Ann Lewis 1 1 Clinical Research Measure,ent of North Texas, Denton, TX, Antioxidant-rich beverages The Body Body density measurement techniques Demsity Body Composition Methods Food waste prevention Body Composition Measurement Techniuqes 3-Compartment Body Composition Measurement Techniques The Metabolic Syndrome References Mezsurement Most full-size techmiques DXA densitometers have techniqies options to determine body composition from Body density measurement techniques total body bone density study. This application was first developed for dual photon absorptiometers, but the almost 1-h scan time made such measurements clinically impractical. In spite of this dramatic improvement in speed, body composition assessment with DXA remains an underutilized application. Most full-size central DXA densitometers have software options to determine body composition from a total body bone density study. The assessment of body composition is much different from the measurement of weight, although certainly the two are related. The assessment of body composition is concerned with the percentage and distribution of fat and lean tissue in the body. Body fat percentage can provide a more techniquew picture of denaity Body density measurement techniques. The errors common to the previously discussed skinfold Body density measurement techniques and the BMI can be somewhat avoided by actually measuring body densitywhich can then measuremment Body density measurement techniques in empirical formulas that interpolate body Nitric oxide booster supplements percentage from ttechniques density. Different oBdy have been developed for males and females in different populations in order to improve accuracy, but the following is once example: [1]. In order to understand those models we first need to understand density and how it can be measured. Your lab for this unit might involve some of these formulas and if you are curious you can read more about those formulasplay with a simulation of hydrostatic weighingcheck out a website that does the calculations for youand see that different formulas have been developed for different population sets in an effort to increase accuracy.
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