Heath (1963) described certain limitations in Sheldon’s method and suggested the following modifications to overcome them:
- Opening the component rating scales to accommodate a broader range of variation by replacing the arbitrary 7-point scale with a rating scale of equal appearing intervals. Beginning theoretically with zero (in practical beginning with one half) and having no arbitrary end point.
- Eliminated the unjustified restrictions of sums of components to between 9 to 12.
- Construct a table that preserves a logical linear relationship between somatotype rating and HWRs.
- Adopt a single table of HWRs (Height-Weight Ratios) and somatotype suitable for both sexes at all ages.
Heath and Carter combined both photoscopic and anthropometric procedures to estimate somatotype. Somatotype is defined as representing the individual’s “present morphological conformation; expressed in a three numeral rating of primary components of physique that identify individual features of morphology and body composition”. In practice, the Heath-Carter method of somatotyping is primarily in its anthropometric form. Anthropometry is more objective and obtaining standardised somatotype photographs is difficult and costly.
The somatotype components and the dimensions used in the Heath-Carter anthropometric protocol to derive each component are as follows:
- 1) Endomorphy (1/2-16th scale): The first component, endomorphy, is described from the sum of three skinfolds namely the triceps, subscapular, and suprailiac. It refers to relative fatness of a physique.
- 2) Mesomorphy (up to 17th scale): The second component, mesomorphy, refers to relative musculoskeletal development adjusted for stature. It is described as expressing fat-free mass relative to stature. Mesomorphy is derived from biepicondylar breadths of the humerus and femur, flexed-arm circumference corrected for the thickness of triceps skinfold and calf circumference corrected for the thickness of the medial calf skinfold corrected of the thickness of medial calf skinfold. Correcting the circumferences is simply a matter of subtracting the skinfold thickness from circumference. These four measurements are then adjusted for stature.
- 3) Ectomorphy (up to 9th scale): The third component, ectomorphy, is the relative linearity of build. It is based on the reciprocal ponderal index.
There are three methods for obtaining a Heath- Carter somatotype. They are as follows:
- 1) The photoscopic somatotype
- 2) The anthropometric somatotype
- 3) The anthropometric plus photoscopic somatotype
The anthropometric somatotype can be calculated from the 10 anthropometric dimensions viz. height, weight and skinfolds (triceps, subscapular, supraspinale, and medial calf), two girths (flexed upper arm and calf) and biepicondylar breadths (humerus and femur).The algorithms for estimating a somatotype with the Heath-Carter anthropometric protocol are as follows:
a) Endomorphy = -0.7182+0.1451 (X)-0.00068(X²)+0.0000014(X³)
Where, X = ∑3 skinfolds viz. triceps, subscapular and supraspinale skinfolds; and adjustment for stature is made where X is multiplied by 170.18/height (cm).
b) Mesomorphy = (0.858 × humerus breadth + 0.601 × femur breadth + 0.188 × corrected arm girth +0.161 × corrected calf girth)-( 0.131× stature)+4.50
Where, corrected arm girth = Arm girth – triceps skinfold in cm and corrected calf girth = calf girth – medial calf skinfold in cm.
c) Ectomorphy = 0.732× HWR -28.58 (If HWR>40.75)
= HWR × 0.463-17.63 (If HWR>38.25 but <40.75)
= 0.1 (If HWR=39.25)
Where HWR = stature/ ³ weight (kg).
The advantages of anthropometric somatotype are it provides
- 1) an objective method of somatotyping.
- 2) the best estimate of a criterion somatotype in the absence of a photograph.
Limitations
- 1) The first component endomorphy represents the fat free mass and second mesomorphy components reflect the fat mass. The body components present specific body composition concepts, which means it partitions body weight into its lean and fat components. Sheldon’s original somatotype concept however refers only to body shape and not to body composition. Although, both methods use the term somatotype, but it has different meaning in each.
- 2) Endomorphy has been found to correlate moderately well in terms of body fat, though fat free mass correlates rather poorly with mesomorphy. Moreover, the association of mesomorphy and limb muscularity is generally low in athletes based on dual energy X-ray absorbtiometry. This needs the validation of relationship implied in the concepts used to define physique.
- 3) The variation in the reproducibility of somatotype components in the HeathCarter anthropometric protocol is guided by intra-observer and inter-observer measurement. An error of 0.5 somatotype units is there when the body dimensions are measured by experienced technicians.
- 4) The validity of this method for children 6 years and below has not been established. This could be one of the factors attributed to studies projecting high ratings of mesomorphy in young children