Growth of fat and lean tissue components at the mid-upper arm in well-off North West Indian children.

Attained means and standard deviations of the mid-upper arm fat cross-sectional area (CSA) and M + B (lean) CSA estimated from the arm circumference and the triceps and biceps skinfolds are presented for 327 girls and 341 boys 6-16 years of age. Tempo unconditional 1-year velocities of the two components were also calculated based on repeated measurements of 244 girls and 253 boys after a period of about 1 year. Although the attained mean total CSA displays a similar pattern in both sexes, the fat and lean components show opposite patterns. Fat CSA is distinctly larger in girls and increases continuously, while fat CSA in boys stabilizes from 10 to 13 years and then decreases. Lean CSA in girls stabilizes at about 13 years, while that of boys continues to increase. Left hand grip strength of boys is greater and increases from 6 to 16 years. The 1-year velocity curves of the girls are shifted by about 1-2 years to the left of the curves for boys, but the pattern is similar. The important features displayed are as follows: occurrence of two spurts of increased velocities, preadolescent and adolescent spurts, an adolescent decline in fat CSA velocities in boys which reaches a nadir at about 14 years, occurrence of an adolescent peak of lean CSA in boys at 14 years, high postpeak velocities of lean CSA in both sexes, which indicates continued growth of lean tissue, and a peak in strength that occurs after that in lean tissue. © 1994 Wiley-Liss, Inc.