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JACKSON-POLLOCK 3-SITE SKINFOLD FORMULA SPECIFICATION

This page describes the formula used in the Jackson-Pollock version of the Skyndex System I.  The Jackson-Pollock is named after the authors of the original research study.  Each formula was developed from the results of underwater weighing and skinfold data taken from several hundred individuals over a wide range of age, body structure, body composition and exercise habits.  Specifically, the formulas are (BD=Body Density):
  • Men 
    BD = 1.10938 – 0.0008267(Y) + 0.0000016(Y2) – 0.0002574(Age)
    where Y= sum of Chest, Abdominal and Thigh skinfolds in mm
  • Women
    BD=1.0994291 – 0.0009929(Z) + 0.0000023(Z2) – 0.0001392(Age)
    where Z = sum of Triceps, Thigh and Suprailliac skinfolds in mm.
In order to be able to quickly input the age and gender into the SKYNDEX I, the formula total age span is divided into five age ranges, with the midpoint of each range actually used in the formula.  For example, for age range 18-26, age 22 is used in the determination of BD.  Due to this, there will be a very slight difference (maximum of 0.5% in the % fat value) if the actual age lies at either extreme of the age range. 
  • Jackson, A.S. and Pollock, M.L. Generalized equations for predicting body density of men. 
    Br.J.Nutr., vol 40:497-504, 1978. (MEN)
  • Jackson, A.S. and Pollock, M.L. and Ward, A. Generalized equations for predicting body density of women.  Medicine and Science in Sports vol 12:175-182, 1980. (WOMEN)

 

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