RESOURCES > DOCUMENTS > About The Skinfold Caliper


PRINCIPLES OF THE SKINFOLD CALIPER

The basic principle of the skinfold caliper is to measure skinfold thickness, then predict Body Density.  Then the Body density is converted to a percent fat using an appropriate population-specific conversion formula. The SKYNDEX calipers have all these formulas and conversions built into the device.

Importance of the caliper pressure

Calipers have to have a consisant pressure throughout the entire range of jaw opening.  This is very important because the equations were developed with a specific pressure of 10g/mm.  Any more or less pressure, then the fat will be compressed (or not compressed enough) and will give innacurate readings.

CALIPER ACCURACY

  1. Which Skinfold Calipers were used to develop the Body Density and %Fat calculation formulas?
    The Harpenden caliper was used by the researchers that developed the equations used in the SKYNDEX devices. SKYNDEX has been shown to give the closest readings to Harpenden than any other high quality caliper (Gruber et al. 1990; Lohman, Pollock et al. 1984; Schmidt & Carter 1990) while providing the automatic calculation of body fat % and eliminating data input errors.

  2. How does the SKYNDEX compare to the Harpinden, Lange and Lafayette Calipers?
    SKYNDEX and Harpenden calipers give similar values when used to measure SKF thicknesses ranging from 4 to 45mm. However, Lange and Lafayette calipers give significantly higher values than the SKYNDEX and Harpenden calipers (Schmidt & Carter, 1990).
    Lange calipers give significantly higher skinfold values than Harpenden (Gruber et al. 1990; Lohman, Pollock et al. 1984; Schmidt & Carter 1990).

The procedure for estimating body composition by measuring skinfolds with skinfold calipers is as follows:

  • Take all measurements on the right side of the body.
  • Identify, measure, and mark the skinfold site.
  • Grasp the skinfold firmly with the tips of the thumb and index finger of the left hand.
  • Lift the pinch. Keep the fold elevated while taking the measurement with the skinfold calipers.
  • Place the jaws of the skinfold caliper perpendicular to the fold, approximately 2 cm below the thumb and index finger and halfway between the crest and the base of the fold. 
  • Release the caliper jaw pressure slowly and record measurement 2 seconds after the pressure is released.
  • Open the jaws of the caliper to remove it from the site.
  • Close the jaws slowly to prevent damage or loss of calibration.
  • A minimum of two measurements should be taken at each site, with at least 15 seconds between measurements to allow the fat to return to its normal thickness. If values vary from each other by more than 10%, take additional measurements.