Assessing percent body fat: Skinfolds

Introduction

A well organised and established set of procedures will ensure that test sessions go smoothly and that there can be no implication of impropriety when measuring subjects. The procedures should include:

·  Prior preparation of equipment and recording forms.

·  Arrangements for a suitable space which is clean, warm and quiet.

·  Securing the assistance of an individual who will record values.

·  Forewarning the subjects that testing will occur at a given time and place.

·  Ensuring that females bring a bikini style swimsuit to facilitate measurements in the abdominal region and that males wear loose fitting shorts or speed swimsuit.

·  The measurer’s technique must include recognition and respect for the notion of personal space and sensitive areas.

·  Great care must be taken in the consistent (reliable) location of measurement sites.

·  Recognition that the data are very powerful in both a positive and negative sense. Young adolescents in particular are very sensitive about their body image and making public specific or implied information on body composition values may have a negative effect on an individual.

Equipment

·  Harpenden Skinfold Callipers

·  Anthropometrical Tape measure

·  Marker Pen

·  Recording Sheet

Skinfold Measurements: General Technique

·  A warm room and easy atmosphere will help the subject to relax which will help you to manipulate the skinfold.

·  During the measurement the subject should stand erect but relaxed through the shoulders and arms.

·  The site should be marked with a washable felt pen.

·  The objective is to raise a double fold of skin and subcutaneous adipose leaving the underlying muscle undisturbed.

·  All skinfolds are measured on the right side of the body.

·  The measurer takes the fold between the thumb and forefinger of the left hand. The procedure is facilitated by a slight rolling and pulling action. The calliper is held in the right hand and the pressure plates of the calliper are applied perpendicularly to the fold and 1cm below or to the right of the fingers depending on the direction of the raised skinfold.

·  The calliper is held in position for 2 seconds prior to recording the measurement to the nearest 0.2mm. The grasp is maintained throughout the measurement.

·  All skinfolds should be measured three times with at least a 2 minute interval to allow the tissue to restore its uncompressed form. The median value is the accepted value.

Percent fat equations

It should be observed that while inter-individual comparisons of percent fat may not be valid between populations, intra-individual comparisons or repeated measurements may provide useful information. The summation of skinfold values will also provide comparative values avoiding some of the assumptions associated with estimates of proportionate fatness. For the purposes of this practical you will use the 4-sites protocol of Durnin and Womersley (1974).

Durnin and Womersley (1974): 4 Sites

·  Body Density = 1.1610 – 0.0632 log∑4 (men)

·  Body Density = 1.1581 – 0.0720 log∑4 (women)

·  Body Density = 1.1533 – 0.0643 log∑4 (boys)

·  Body Density = 1.1369 – 0.0598 log∑4 (girls)

Calculating %Fat (Siri, 1956) = [(4.95/body density) – 4.5] x 100

(where ∑4 = ∑4 skinfolds in millimetres (mm))

The Sites

·  Triceps

·  Biceps

·  Subscapular

·  Iliac Crest (Termed by Durnin and Womersley as ‘Suprailiac’)

Locations of Skinfolds

·  Triceps: Vertical skinfold raised on posterior aspect of the triceps, exactly hallway between the olecranon process and the acromion process when the hand is supinated

·  Biceps: Vertical skinfold raised on the anterior aspect of the biceps, at the same horizontal level as the triceps skinfold

·  Oblique skinfold raise 1cm below the inferior angle of the scapular at approximately 45° to the horizontal plane following the natural cleavage lines of the skin.

Record data and calculate %body fat

·  ∑4 skinfolds (mm) =

·  Body Density =

·  %Body Fat =