Age and body type comparisons of the mass distributions of children.

Mass distribution profiles for children were constructed using a mathematical model of the body. The model was based on the assumption that the body is composed of 2 cm wide elliptical zones of known density. The method was judged to be accurate in terms of body mass estimations with a mean error of 0.61% (N = 12). Profiles were compared across somatotypes (endomorph, mesomorph, ectomorph) for four age levels (nominally, 12-, 9-, 6- and 4 years). The profiles showed differences in mass distribution with endomorph profiles tending to peak at the mid-trunk level, mesomorphs tending to have a lower profile and peaking at the shoulder or lower chest levels and ectomorphs having an even lower profile which was relatively constant through the trunk/upper extremity region. Profiles were also compared across ages for each somatotype and were found to become more angular as the child became older due to the regional growth of structural features such as the shoulders, chest, waist, pelvis and knees. These differences and the relatively small differences for the head were accentuated by creating a hypothetical scaled curve for a 4 year old compared with a 12 year old.