Design and Accuracy of Calipers for Measuring Subcutaneous Tissue Thickness

Abstract

A considerable proportion of the body fat lies in the subcutaneous tissue which, in many parts of the body, is only loosely attached to the underlying tissue and can be pulled up between the thumb and forefinger into a fold (Pl. I). The thickness of this fold of skin and subcutaneous tissues can be measured by applying some form of caliper to either side of it, and this technique has been widely used to give an estimate of body fat by those concerned with nutrition (Sinclair, 1948; Keys & Broiek, 1953), with fat distribution (Edwards, 1950), with child growth (Franzen, 1929; Reynolds, 1950; Tanner, 1953) and with anthropometric surveys (Berry, Cowin & Magee, 1951 ; Hammond, 1953). However, the observed thickness depends on how the skinfold is picked up and on the design of the caliper with which it is measured; if, for example, the jaws of the caliper are approximated by a spring the reading will depend on the strength of the spring, since the tissue is compressible. Despite these facts, there has been little information published on the best design of skinfold calipers, and no general standardization either of instrument or of technique. Hence the comparison of the results of different observers is usually impossible, and much work in the field is vitiated. The purpose of the present investigation was (a) to test various designs of caliper and to recommend principles that all calipers should follow, and (b) to introduce, and test the accuracy of, a new skinfold caliper which we believe to be the most satisfactory yet produced. The paper is divided into two parts : Part I describes two experiments on caliper design and ends with a set of general recommendations; Part z describes the new caliper and gives the results of three experiments made to assess its accuracy in practical use.