GROWTH, PUBERTY AND EXERCISE
Rogol, A. D. (1994). Growth at puberty: interaction of androgens and growth hormone. Medicine and Science in Sports and Exercise, 26(6), 767-770.
Puberty is characterized by the onset and continued development of secondary sexual characteristics and an abrupt onset of linear growth. The secondary sexual characteristics are a result of androgen production from the adrenals in both sexes (adrenarche) and testosterone from the testes in the male and estrogens from the ovaries in females (gonadarche).
During early childhood linear growth velocity declines rapidly to reach a constant childhood rate of approximately 5.5 cm per year. With the onset and progression of pubertal development, the rate accelerates markedly to reach a peak during mid-adolescence (later in the developmental process in boys compared with girls) and then diminishes toward zero as the bony epiphyses fuse. Pubertal growth spurt cannot occur without sufficient quantities of growth hormone. hGH alone apparently is not sufficient, since important physiological synergism exists between the gonadal axis and hGH secretion coincident with the progression of puberty.
Shortly after cessation of linear growth, the circulating pattern of hGH returns to the prepubertal configuration with the result that the hGH concentration versus time profiles in young men are remarkably similar to those in prepubertal boys, but greater than those in older men despite a continued rise in serum testosterone concentration. hGH secretion (and other pituitary hormones) occurs in a repetitive, burst-like manner.
The pubertal growth spurt is likely subserved by altered neurosecretory
dynamics for growth hormone. The augmented hGH secretion apparently
results from an increase in the maximum rate of hGH release rather
than from an increase in hGH burst frequency caused in the main
by increasing amounts of circulating gonadal steroid hormones.
The markedly altered hormone levels subserve the equally profound
changes in body composition, regional fat distribution, and muscular
strength. Gonadal steroid hormones strongly regulate growth and
hGH secretion at puberty. However, any straightforward relationship
between growth velocity and the circulating hGH concentrations,
or attributes of hGH neurosecretion, is diffused by the added
components of hGH binding proteins, circulating IGF-1 and its
binding proteins, and the complex metabolic signals that reflect
the relative fatness of an individual, even when well within the
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