Plasticity of adolescent growth in boys

The present analysis examines the plasticity of adolescent growth in 21 selected historic and recent growth studies from 6 European countries, the U.S., and Japan, during the last 150 years. Mean stature at the age of 6 years has significantly increased by approximately 6 mm per decade (P < 0.05), whereas adult stature has risen by approximately 10 mm per decade (P < 0.01). Developmental tempo has also increased. Mean age at take-off significantly dropped by approximately 2 years per century (P < 0.01), and age at peak height velocity by 1.7 years per century (P < 0.01). Yet, the secular trend affected different parts of the growth curves in a different way so that the shape of the growth curves has also changed. Whereas adolescent growth rose significantly in the last century (P < 0.01) and increasingly contributed to the improvement of adult stature, no significant modification of the prepubertal portion was evident. Though early childhood and adolescent growth appeared equally plastic, both parameters were statistically independent, indicating differences in the regulation of early and adolescent growth. Yet, the factors that regulate adolescent growth still remain to be elucidated. (C) 1997 Wiley-Liss, Inc.