yesterday I had my body fat percentage tested. here is a little info for those interested:
The most accurate estimation of body composition is achieved by use of the underwater or hydrostatic weighing technique. Obviously this method places severe restrictions on both practicality and convenience, and the alternative basis of skinfold thickness measurements are therefore used in all but the most stringent of requirements.
The use of skinfold calipers in the performance of skinfold thickness measurements(form which are derived the estimates of body fat) has been well established and documented over the last 40 years. These thickness measurements do not measure overall body fat mass or it’s percentage directly but rely on validated equations that describe the relationship between measures of skinfold fat as well as other body dimensions and the measured body density. Body fat percentage is determined from the estimate of body density.
Various experimenters have put forward equations which are used with either skinfold thickness alone or in conjunction with other measurements such as body circumference of limb lengths. Two of the most common sets of equations used are attributable to Durin & Womersley (skinfolds alone), and to Jackson & Pollack (skinfolds and body measurements). The results obtained from the equations (that of body fat density) is subsequently used in the siri equation to calculate the body fat.
Skinfold measurements, when properly taken, correlate very highly (0.83 to 0.89) with hydrostatic weighing, with standard error of only about 3 or 4%. In comparison, the correlation of height and weight charts is much lower at about 0.60.
Taking Skinfold Measurements:- The accuracy of measurement is, as one would expect, dependent upon the accuracy of the equipment used, the correct selection and location of the skinfold sites, the proper technique in taking the measurements, and the experience of the tester.
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Measurement should be taken on dry skin. Moist skin is harder to grasp and can influence the measurement.
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Instruct the test subject to keep muscles relaxed during the test.
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Take all measurements on the right side of the body. An exception might be where a deformity or missing limb would necessitate using the left side.
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Mark the skinfold site using a pen . Use a tape measure to accurately find the mid points.
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The skinfold should be firmly grasped by the thumb and index finger, using the pads at the tip of the thumb and finger. Gently pull skinfold away from the body.
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The calipers should be placed perpendicular to the fold on the site marked, dial up, at approximately 1cm below the finger and thumb. While maintaining the grasp of the skinfold. Try to visualise the location of a true double fold of skin thickness, and place calipers there.
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A minimum of two measurements should be taken at each site. If repeated tests vary by more than 1mm, repeat the measurement. If consecutive measurements become increasingly smaller, the fat is being compressed. Go to another site, come and test the site a little later.
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The final value recorded should be the average of the two that seems to best represent the skinfold site.
Site selection:- is very important and frequently a source of error in skinfold testing. The sites selected must match the particular protocol being used. There are two protocols usually involved, the 4-site system being the most commonly used. This system is the same for male and female subjects.
The second system uses three sites, the sites differeing for either male and female subjects, and are used in conjunction with the body density formulae (Jackson & Pollock).
The 4-site system for male and female subjects. Biceps- The anterior surface of the biceps midway between the anterior auxiliary fold and the antecubital fossa. Triceps- A vertical fold on the posterior midline of the upper arm, over the triceps muscle, halfway between the acrosion process, and olecranon process. The elbow should be extended and the arm relaxed. Subscapular- The fold is taken on the diagonal line coming from the vertebral border to between 1 and 2 cm from the inferior angle of the scapulae.
Suprailiac- A diagonal fold above the crest of the ilium at the spot where an imaginary line would come down from the anterior auxiliary line.
and here are my measurements and and precentages:
Skinfold Site Skinfold (mm)
Triceps 3.25
Biceps 2
Subscapular 8
Suprailiac 8.25
Supraspinale 6
Abdomen 8.25
Chest 2.5
Front Thigh 5.25
Medial Calf 3
- Durin and Womersley (1974)
∑ triceps, biceps, subscapular, suprailiac= 21.5mm
8.1% fat mass
- Yuhasz (1982)
∑ triceps, subscapular, suprailiac, abdomen, front thigh, chest=35.5 mm
6.7% fat mass
- Jackson and Pollock (1985)
∑ abdomen, chest, front thigh= 16mm
3.8% fat mass
Comments:
I’m glad to see it’s low, but a little skeptical on some of the figures (3.8% ~ ya right). I’ll stick with the 8.1 or even 10 and base my caloric intake on that.
My nutrition is very close to this:
Non-Workout Days (4 days/week):
112g Carbs
240g Prot
3090 Cal
Work-Out Days (3 days/week):
333g carbs Carbs
300g protein
4333 Cal
Enjoy the weekend!