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anthropometry

Plicometry

One of the most precise methods for assessing body composition

INTRODUCTION

Among the various methods of measuring the percentage of body fat, the PLICOMETRY represents one of the simplest, most precise and with the purchase costs of the contained instrumentation.

THE PLACER

The plicometro is an instrument that can be compared to the caliber of a mechanic because it consists essentially of a caliper and a graduated scale that measures the distance between the tips. The plicometer should exert a constant pressure between the folds of 10g / mm ² (if the pressure is different the suboptimal compression of the plica will cause errors in the detection phase). It is therefore advisable to periodically check the gauge according to the manufacturer's instructions (pressure, distance from the tips). As we have seen in the introductory part, there are various types ranging from the cheapest ones in plastic, not suitable for scientific surveys, to the more professional ones in metal. The latter are the most used in the anthropometric field and are essentially three: Lange USA, 65mm; Harpenden GB 55 mm, Holtain 50 mm (the mm represent the measure of the maximum opening of the pliers).

The type of gauge used introduces error in the measurement

GAUGEJACKSON-POLLOCKDurnin-Womersley
Lange23.4%26.9%
Harpeden19.6%23.8%

Note: The calculation of fat mass was done using the Lohman equations

Analyzing the following table we can appreciate how between one type of caliber and the other (note that both are scientific calibres) there is an error of about 15%. This data is a further confirmation that in assessing body composition there are no 100% precise methods; in fact only the dissection of the corpse would give correct results but I believe that none of you wishes to undergo this method !!

DETECTION TECHNIQUE

The correct detection technique is FUNDAMENTAL to avoid introducing further measurement errors. The following guidelines must therefore be respected:

  1. Carry out the measurements on the left side of the body by convention (without taking into account the preference side of the subject, unless the left is impossible or you want to detect both or just the right for rehabilitation problems). On the other hand, in the literature there are also authors who advise to carry out the surveys on the right side of the body.
  2. Identify the site and mark it with a lapographic paper
  3. Hold the caliper with the right hand and grasp a fold between the thumb and forefinger of the left hand, trying to detach the underlying muscle tissue.
  4. The fingers must be 8 cm apart, on a line perpendicular to the longitudinal axis of the panniculus.
  5. Use a right hand pressure to separate the branches of the gauge, apply the gauge to the base by inserting it at 90 °.
  6. Always keep the fold between your fingers and release the caliper pressure slowly.
  7. Read after 2 seconds.
  8. Open the gauge, remove it and close it slowly.
  9. Repeat the measurement 2 times (with at least 2 minutes interval to allow the plica to return to the incompressed form) and then average. If the two measurements vary between them more than 10% need to perform a third one.

THE POINTS OF REPERE

The size of the fat pads can be taken in different locations, the most used are:

Chest : the fold is taken in a diagonal direction between the axilla and the nipple;

Subscapular : the plica is taken diagonally, at the lower corner of the scapula;

Axillary : the fold is taken horizontally below the area covered with hair;

Abyssilia : the plica is taken obliquely, just above the iliac crest;

Abdominal : the fold is taken vertically (or horizontally depending on the authors), 2 cm lateral to the navel;

Triceps : the fold is taken vertically, in the middle of the measured arm flexed;

Biceps : the fold is taken vertically, in the middle of the extended arm;

Thigh : the fold is taken vertically, at the center of the distance between the inguinal fold and the patella;

Calf : the plica is taken vertically, at the point of greatest development of the part and in its medial portion;

MISTAKES

The errors that can be committed during the survey are very many and it is important to know them in order to reduce them as much as possible. Below are schematically reported all the possible causes of error.

1) Operator skill

The wrong location of the folds causes errors in the measure:

a) Intra-observer error: error associated with the same detector on repeated measurements on the same subject. It varies with the site and is greater for abdomen (8.8%) and thigh (7.1%) because in these sites the amount of subcutaneous adipose tissue is greater. Experience. Subject's amount of fat: the more fat a person is, the more difficult the detection becomes; in fact, in obese and very muscular individuals, subcutaneous adipose tissue does not easily separate from the underlying muscle. Moreover in the obese the thickness of the folds exceeds the maximum opening of the caliber. The only alternative is to take sites where the subcutaneous fat is minimal (biceps).

b) Inter-observer error: error associated with different detectors The objectivity of the measurements improves when the detectors follow standardized procedures, practice together and mark the sites.

2) Type of caliber

Check: Accuracy Accuracy Measurement range Pressure N: B: Use the same gauge for repeated measurements on the same subject.

3) Factors related to the subject

Skin thickness (0.5-2 mm). Compressibility of adipose tissue. Hydration level. Do not take the measurement after workout, sauna, Turkish bath, swimming or shower as physical exercise, hot water and heat produce hyperemia (increased blood flow) in the skin with consequent increase in skin thickness.

4) Prediction equations used: there are two classes of equations:

specific population equations, derived from a limited and homogeneous sample and applicable only to a specific population (for example in the evaluation of the body composition of cyclists).

generalized equations, derived from large heterogeneous samples that vary in age and adiposity (eg evaluation of body composition of Italians)

CONTINUE: Usefulness of plicometry »

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