Bodyfat testing methods

[w8's]

Whats the difference in the different b/f calculation methods and which is the most reliable.

Jackson/Pollock formula

or

Durnin/Womersley formula


any help would be greatly appreciated

 

[Entity]

Both methods you mentioned are different ways of intergrating the information gathered by the Skinfold Method which is accurate to within 3-5% but its accuracy also depends on the skill of the tester, therefore its the least accurate of the three common methods.
The next is Bioelectrical Impedence where a voltage is passed through your body to determine bodyfat. The signal travels quickly through muscle because muscle is made up of 70% water and water conducts electricity. Fat is only 5 to 10% water so it slows down the signal. The slower the signal the more fat you have. Dehydration can make the readings false because less water is in your system and if you are really fat or really lean this test may not produce good results. Otherwise its accurate to within 3-4% percent.
The most accurate method of testing is Underwater Weighing. You get into a tank of water on a scale. Here is the hard part, you have to blow all of the air out of your lungs and bend forward until you are completely submerged. Make sure to get all of the air out because any extra air makes you appear fatter. You wait about 5 seconds under water while your weight is taken.
Your underwater weight is figured out by a mathematical algorithm that determines your bodyfat. This test is based upon the premise that muscle sinks and fat floats. Muscle is denser than fat therefore it sinks. The margin of error on this test is 2 percent.

 

[homonunculus]

Whats the difference in the different b/f calculation methods and which is the most reliable.

Jackson/Pollock formula

or

Durnin/Womersley formula


any help would be greatly appreciated

Both are skinfold based estimations of body fat, as estimated by underwater weighing.

I would go with the Jackson & Pollock:

Med Sci Sports Exerc. 1985 Feb; 17(1): 124-30. Related Articles, Links

Validity of "generalized" equations for body composition analysis in male athletes.
Sinning WE, Dolny DG, Little KD, Cunningham LN, Racaniello A, Siconolfi SF, Sholes JL.
Equations by Durnin and Womersley [(D-W), Br. J. Nutr. 32:77, 1974], Jackson and Pollock [(J-P), Br. J. Nutr. 40:497, 1978], and Lohman [(L), Human Biol., 53:181, 1981] for estimating body density (BD) purportedly overcome the problem of specificity by accounting for age and/or the curvilinear relationship between skinfolds (SF) and BD. Their equations were validated on 265 male athletes against percent fat measured by underwater weighing [(UWW); mean +/- SD = 9.2 +/- 4.4%]. Equations by Sloan [(S), J. Appl. Physiol. 23:311, 1967], Katch and McArdle [(K-M), Human. Biol. 45:445, 1973], and Forsyth and Sinning [(F-S), Med. Sci. Sports 5:174, 1973] were included as "linear regression models" to compare to the curvilinear models of J-P, D-W, and L. Differences between UWW and estimated mean values ranged from -1.1 to +5.9%; correlations ranged from 0.58 to 0.85; SEE ranged from +/- 2.41 to +/- 3.61% and total error (E) ranged from 2.38 to 6.97%. The seven D-W equations overestimated mean percent fat by from 3.9 to 5.9%. The K-M, S, and L equations overestimated by 1.3, 0.5, and 1.7%, respectively. The F-S equations overestimated by 2.4 to 3.8%. Of the 21 equations evaluated, only 3 by J-P gave estimates not significantly different from UWW percent fat. Regression analyses of the relationship between UWW and estimated (x) percent fat values from those equations were: y = 1.037x - 0.08 +/- 2.38, E = 2.38, r = 0.84; 0.869x + 1.36 +/- 2.45, E = 2.51, r = 0.83; 1.107x - 1.14 +/- 2.51, E = 2.53, r = 0.82.(ABSTRACT TRUNCATED AT 250 WORDS)

-Randy

 

[bigheinz]

I use Parrillo Performance with my clients and athletes, is easy and is very popular. Impedance methods are very bad.

 

[Entity]

Bodyfat Scales

Has anyone ever used one of those scales that also measure bodyfat. Im thinking about getting one but I heard that they can be very inaccurate but I figured that if they are consistant with their measurments then the change in bodyfat can be accuratly tracked and thats really whats important. So what do you think?

 

[w8's]

Re: Re: Bodyfat testing methods

Both are skinfold based estimations of body fat, as estimated by underwater weighing.

I would go with the Jackson & Pollock:

Med Sci Sports Exerc. 1985 Feb; 17(1): 124-30. Related Articles, Links

Validity of "generalized" equations for body composition analysis in male athletes.
Sinning WE, Dolny DG, Little KD, Cunningham LN, Racaniello A, Siconolfi SF, Sholes JL.
Equations by Durnin and Womersley [(D-W), Br. J. Nutr. 32:77, 1974], Jackson and Pollock [(J-P), Br. J. Nutr. 40:497, 1978], and Lohman [(L), Human Biol., 53:181, 1981] for estimating body density (BD) purportedly overcome the problem of specificity by accounting for age and/or the curvilinear relationship between skinfolds (SF) and BD. Their equations were validated on 265 male athletes against percent fat measured by underwater weighing [(UWW); mean +/- SD = 9.2 +/- 4.4%]. Equations by Sloan [(S), J. Appl. Physiol. 23:311, 1967], Katch and McArdle [(K-M), Human. Biol. 45:445, 1973], and Forsyth and Sinning [(F-S), Med. Sci. Sports 5:174, 1973] were included as "linear regression models" to compare to the curvilinear models of J-P, D-W, and L. Differences between UWW and estimated mean values ranged from -1.1 to +5.9%; correlations ranged from 0.58 to 0.85; SEE ranged from +/- 2.41 to +/- 3.61% and total error (E) ranged from 2.38 to 6.97%. The seven D-W equations overestimated mean percent fat by from 3.9 to 5.9%. The K-M, S, and L equations overestimated by 1.3, 0.5, and 1.7%, respectively. The F-S equations overestimated by 2.4 to 3.8%. Of the 21 equations evaluated, only 3 by J-P gave estimates not significantly different from UWW percent fat. Regression analyses of the relationship between UWW and estimated (x) percent fat values from those equations were: y = 1.037x - 0.08 +/- 2.38, E = 2.38, r = 0.84; 0.869x + 1.36 +/- 2.45, E = 2.51, r = 0.83; 1.107x - 1.14 +/- 2.51, E = 2.53, r = 0.82.(ABSTRACT TRUNCATED AT 250 WORDS)

-Randy

Thanks this is what i was looking for. i looking for the best calculation to use on my clients.