The effect of a 12-month growth period on the body moments of inertia of children.
The effect of growth over a 12-month period on the principal moments of inertia for the body was investigated. The body was considered to be modelled as composed of elliptical zones 2 cm wide. Twelve children between the ages of 4 and 12 years and of different body types were tested and retested after 12 months. Moments of inertia for the three principal axes were calculated. A comparison of the results for the moment of inertia about the centroidal transverse axis showed increases from 12-57%. The results for the longitudinal centroidal axis ranged from 8-92%. For most of the children these percentage changes exceeded those in the traditional indicators of age, height, and mass. The product, mass times height squared (MH2), appeared to indicate the changes more accurately. Extreme changes were noted for a 12/13-year-old undergoing pubescent growth, a 6/7-year-old ectomorph, and a 4/5-year-old endomorph. It is suggested that the extreme changes, in particular, would make rotational movements difficult and there could be an extended adaptation period.
D000293:Adolescent; D000886:Anthropometry; D002648:Child; D002675:Child, Preschool; D006128:Growth; D006801:Humans; D008297:Male; D008433:Mathematics; D008954:Models, Biological; D009068:Movement; D011627:Puberty; D013008:Somatotypes