Plicometro

[Fandango]

Vorrei valutare la % di grasso misurando le pliche in almeno 5 punti del corpo. Qualcuno sa indicarmi dove reperire la formula?:cool:

[max_power]

Gawain dovrebbe avere i punti di repere.

max_power

[mikeshell]

http://weightrainer.virtualave.net/bodycalc.html

però è solo 3 e 7.

Altrimenti usa il prog. bodycomp

Ciao
Mike

[Gawain]

Skinfold Methods for Bodyfat Estimation in Men



( by Konstantin Zahariev)

Note: The methods listed here were chosen on the basis of being popular (widely used) and/or adequate for lean men and/or adequate for exercising men and/or adequate for young athletes. See the usage recommendations below. Listed are methods incorporating only skinfold measurements. The methods (but not every one of them) cover men from 16 to 60 years old.

Measurement sites:


[1] Chest
[2] Abdomen
[3] Thigh
[4] Triceps
[5] Biceps
[6] Subscapular
[7] Suprailiac
[8] Axilla
[9] Calf
[10] Lower back

Measurements:


[1] Chest: a DIAGONAL fold on the lateral edge of the pectoral muscle, halfway between the nipple and the anterior axillary line (front of underarm crease). The fold should be parallel to the edge of the pectoral muscle.

[2] Abdomen: a VERTICAL fold one inch to the right of the umbilicus.

[3] Thigh: a VERTICAL fold in the middle of the front thigh, halfway between hip and knee joints.

[4] Tricep: a VERTICAL fold halfway between the shoulder and elbow joints, on the posterior midline of the upper arm (over the tricep muscle).

[5] Bicep: a VERTICAL fold halfway between the shoulder and elbow joints, on the anterior midline of the upper arm.

[6] Subscapular: a DIAGONAL fold at the back, just below the inferior angle of the scapula, at a 45deg. angle WRT horizontal, turning clockwise.

[7] Suprailiac: a DIAGONAL fold just above the iliac crest, at the spot where the anterior axillary line would come down (this is about 1/4 way between the midaxillary line and the umbilicus), at about 30deg. angle WRT horizontal, turning clockwise.

[8] Axilla: a VERTICAL fold on the midaxillary line at the level of the nipple.

[9] Calf: a VERTICAL fold in the middle of the medial head of the gastrocnemius.

[10] Lower back: a HORIZONTAL fold approximately at the position of the kidney (about 2 inches to the right of the spine,
and 1 inch above the umbilicus level).

Methods:

- Jackson-Pollock 7-site [JP-7]: S=[1]+[2]+[3]+[4]+[6]+[7]+[8]
- Jackson-Pollock 3-site [JP-3]: S=[1]+[2]+[3]
- Pollock et al. 3-site [Pa-3]: S=[1]+[4]+[6]
- Lohman 3-site [L-3]: S=[2]+[4]+[6]
- ?? 4-site [??-4]: S=[1]+[2]+[7]+[8]
- Forsyth-Sinning 4-site [FS-4]: [2], [4], [6], [8]
- Sloan 2-site [S-2]: [3], [6]
- Parrillo 9-site [P-9]: S=[1]+[2]+[3]+[4]+[5]+[6]+[7]+[9]+[10]
- Durnin-Womersley 4-site [DW-4]: S=[4]+[5]+[6]+[7]

Organizations:


- NHCA (uses ??-4)
- ACSM (uses JP-3) [American College for Sports Medicine]
- CHP (uses DW-4) [Creative Health Products - SlimGuide calipers]

Formulae:


[JP-7]: (S=[1]+[2]+[3]+[4]+[6]+[7]+[8], in mm)

a. Body_Density = 1.112 - 0.00043499*S + 0.00000055*(S^2) - 0.00028826*Age
b. Bodyfat_% = 495/Body_Density - 450 (Siri, 1961. Also see Addendum)

[JP-3]: (S=[1]+[2]+[3], in mm)

a. Body_Density = 1.1093800 - 0.0008267*S + 0.0000016*(S^2) - 0.0002574*Age
b. Bodyfat_% = 495/Body_Density - 450 (Siri, 1961. Also see Addendum)

[Pa-3]: (S=[1]+[4]+[6], in mm)

a. Body_Density = 1.1125025 - 0.0013125*S + 0.0000055*(S^2) - 0.000244*Age
b. Bodyfat_% = 495/Body_Density - 450 (Siri, 1961. Also see Addendum)


[L-3]: (S=[2]+[4]+[6], in mm)

a. Body_Density = 1.0982 - 0.000815*S + 0.0000084*(S^2)
b. Bodyfat_% = 495/Body_Density - 450 (Siri, 1961. Also see Addendum)

[??-4]: (S=[1]+[2]+[7]+[8], in mm)

Bodyfat_% = 0.27784*S - 0.00053*(S^2) + 0.12437*Age - 3.28791

[FS-4]: ([2], [4], [6], [8], in mm)

a. Body_Density=1.10647 - 0.00144*[2] - 0.00077*[4] - 0.00162*[6] + 0.00071*[8]
b. Bodyfat_% = 495/Body_Density - 450 (Siri, 1961. Also see Addendum)

[S-2]: ([3], [6], in mm)

a. Body_Density = 1.1043 - 0.001327*[3] - 0.001310*[6]
b. Bodyfat_% = 495/Body_Density - 450 (Siri, 1961. Also see Addendum)

[P-9]: (S=[1]+[2]+[3]+[4]+[5]+[6]+[7]+[9]+[10], in mm)

Bodyfat_% = (27*S)/Body_Weight (Body_Weight is in pounds)

[DW-4]: (S=[4]+[5]+[6]+[7], in mm)
Has 5 different formulae of the type Density=c-m*log10(S) for 5 different age groups, for determining body density; 4 out of 5 groups are small (35 people or less), and 1 out of these four did not have very lean people in it, and its regression fit has a much different slope than the other 4. Instead, I've constructed one proxy formula with a linear age dependence, for (my) convenience: [DW-4m] =>[DW-4m]:

a. Body_density = 1.1714 - 0.063*log10(S) - 0.000406*Age
b. Bodyfat_% = 495/Body_density - 450 (Siri, 1961. Also see Addendum)

If you use or have access to matlab, you might benefit from this matlab script I wrote. It takes your age, weight, and all 10 measurements, and produces a table of the respective skinfold sums and their squares, and of body densities and bodyfat (percentages and pounds), for all 9 methods.

[Image] You can also enter a reference age now (see Usage Recommendations below for details).

To use it only for one particular method (or several), enter the appropriate measurements, and enter zeros for the measurements that do not apply.

General notes:


(I cannot comment on [??-4] and [P-9] as I have no idea how they were developed and validated; incidentally they are the only ones not following the practice of relating skinfolds to body density)

In mfw archives I found info on [DW-4], [JP-3], [P-9], [??-4]. Other popular methods seem to be [JP-7] and [S-2] - they were mentioned by name.

[Gawain]

Historically the methods evolved as follows:

- first were formulae with one or several skinfolds, each skinfold entering linearly but with different factor (examples are [S-2],
[FS-4]); no age dependence;
- it was realized that 1) all skinfolds should have the same factor, i.e. the sum of skinfolds S should be used, 2) the skinfolds-density
relationship is not linear, 3) age should enter the formulae because with aging a higher proportion of one's bodyfat is internal;
- [DW-4] devised their formulae incorporating the above, but used an awkward method, separating subjects into age groups (most of which
too small statistically - groups had 24,92,34,35,24 men) and formulating different equations for each separate group. The sum of skinfolds S entered the formulae, and a logarithmic dependence was assumed (i.e. a linear log10(S)--density relationship);
- Jackson-Pollock introduced 1) a polynomial (quadratic in S) dependence, 2) a linear age dependence. Their group had 308 men, with a cross-validation of the formulae on another 95 men.
- subsequently, investigators devised formulae generally having the same characteristics as Jackson-Pollock's.

Usage recommendations:

(remember those do not include [??-4] and [P-9] due to lack of info)

- Men in early 20s or younger can use any of the above (however [DW-4] has a significantly larger error than the rest when validated on adolescent athletes) according to Thorland et al. (1984);
- Men older than early 20s should probably shy away from formulae that do not have an age dependence, so good choices for them are [JP-7], [JP-3], [Pa-3]. [Image] - however, if you are concerned with visual appearance only (i.e. subcutaneous fat), then internal fat (a function of age) is irrelevant and you might want to use a constant "reference" age for the equations in order to correlate BF% with your appearance, year after year.
- Lean men should probably avoid [DW-4], especially if they are in the 30-39 age range.
- overall, [JP-7] and [JP-3] should probably be on top of your list.
- you can use several methods and average the results.


Addendum: Relating body density to bodyfat percentage; the Siri formula


Consider a 2-compartment model of the human body:
- lean body compartment with volume Vb, (average) density Db, mass Mb;
- fat compartment with volume Vf, density Df, mass Mf;
- the whole body has volume V, (average) density D, mass M.
Equazioni Siri:

Volume conservation: Vb + Vf = V (1)

Therefore Mb/Db + Mf/Df = M/D (2)

Let f=Mf/M be the fat mass proportion, b=Mb/M be the lean body mass proportion.



Note that b=1-f (3)
infatti la massa magra corrisponde alla differenza tra' l'intero (il peso corporeo) e la massa grassa

Divide (2) by M, and use (3): 1/D = f/Df + (1-f)/Db (4)

Therefore f = 1/D*(Db*Df/(Db-Df)) - (Df/(Db-Df)) (5)

Several studies (using human cadavers) calculated the density of lean body Db to be 1.100 kg/L (yes, that's four significant figures), and that of fat Df to be 0.900 kg/L.

Siri took these values and plugged them into the general formula (5), getting:

f = 4.95/D - 4.5, which, multiplied by 100 to get percentages, is:

Bodyfat_% = 495/Body_Density - 450

Note that Siri's formula would blow up and give you negative Bodyfat_% if you feed it with densities higher than 1.1 kg/L, since 1.1 kg/L is the assumed density of lean body mass.


Methods References:

[JP-7, JP-3] Jackson and Pollock 1978:
Generalized equations for predicting body density of men.
A.S. Jackson and M.L. Pollock. Br J Nutr, 40(3):497-504, Nov 1978.

[Pa-3] Pollock et al. 1980:
Measurement of cardiorespiratory fitness and body composition in the
clinical setting. M.L. Pollock, D.H. Schmidt, and A.S. Jackson.
Compr Ther 6:12-27, 1980.

[L-3] Lohman 1981: (listed under review articles below)

[FS-4] Forsyth and Sinning 1973:
The anthropometric estimation of body density and lean body weight
of male athletes. H.L. Forsyth and W.E. Sinning. Med Sci Sports
5(3):174-180, 1973.

[S-2] Sloan 1967:
Estimation of body fat in young men. A.W. Sloan. J Appl Physiol,
23(3),:311-315, Sep 1967.

[P-9] Parrillo 1993:
High-performance bodybuilding. J. Parrillo and M. Greenwood-Robinson.
Berkeley Publishing group, NY. pp. 169-172.

[DW-4] Durnin and Womersley 1974:
Body fat assessed from total body density and its estimation from
skinfold thickness: measurements on 481 men and women aged from 16
to 72 years. J.V. Durnin and J. Womersley. Br J Nutr, 32(1):77-97,
Jul 1974.

Review articles:

- Lohman 1981:
Skinfolds and body density and their relation to body fatness: a
review. T.G. Lohman. Hum Biol, 53(2):181-225, May 1981.

- Lohman 1982:
Body composition methodology in sports medicine. T.G. Lohman. Phys
Sportsmed, 10(12):47-58, Dec 1982

- Jackson and Pollock 1985:
Practical Assessment of Body Composition. A. S. Jackson and M.L.
Pollock. Phys Sportsmed, 13(5):76-90, May 1985.

Other references:

- Siri, A.W. 1961:
Body composition from fluid spaces and density: Analysis of
methods. In: Techniques for measuring body composition, J. Brozek
and A. Hanschels, ed. National Academy of Science, National Research
Council, Washington, D.C., pp. 223-244. 1961.

- Brozek et al. 1963:
Densitometric analysis of body composition: revision of some
quantitative assumptions. J. Brozek, F. Grande, J.T. Anderson, and
A. Keys. Ann NY Acad Sci, 110:113-140, 1963.

- Thorland et al. 1984:
Validity of anthropometric equations for the estimation of body
density in adolescent athletes. W.C. Thorland, G.O. Johnson,
G.D. Tharp, T.G. Fagot, and R.W. Hammer. Med Sci Sports Exerc,
16(1):77-81, 1984

- Behnke and Wilmore 1974:
Evaluation and regulation of body build and composition. A.R. Behnke
and J.H. Wilmore. Englewoon CLiffs, NJ, Prentice Hall, 236pp., 1974.

Abbreviations:

Ann NY Acad Sci = Annals of the New York Academy of Sciences
Br J Nutr = British Journal of Nutrition
Compr Ther = Comprehensive Therapy
Hum Biol = Human Biology
J Appl Physiol = Journal of Applied Physiology
Med Sci Sports = Medicine and Science in Sports
Med Sci Sports Exerc = Medicine and Science in Sports and Exercise
Phys Sportsmed = The Physician and Sportsmedicine

[Fandango]

Non ho parole :

mi sento come un cercatore che ha appena trovato una miniera (d'informazioni questa volta)
Vi ringrazio.