Hormones (Athens). 2003 Apr-Jun;2(2):103-12.
The influence of exercise on growth hormone and testosterone in
prepubertal and early-pubertal boys.
Tsolakis C, Xekouki P, Kaloupsis S, Karas D, Messinis D, Vagenas G,
Department of Physical Education and Sports Science, Athens University, Athens, Greece. firstname.lastname@example.org
The purpose of this study was two fold a) to determine the levels of hormonal parameters which are related to growth and sexual maturation (T, SHBG, FAI, GH) in 66 pre-pubertal and early-pubertal boys (11-13 years old) who systematically engage in individual and team sports activities of endurance, strength, speed and skill, respectively, and b) to investigate the effect of two different forms of exercise namely aerobic (AG) and weight training (WG) on androgen levels in 19 sedentary pre-pubertal boys. The control groups (CG) consisted of boys of the same age who attended only the school physical education programmes. The individuals included in the study participated voluntarily after their parents had been informed and had given their written consent. Hormonal concentrations were determined using radioimmunoassay and
immunoradiometric assays. No differences were observed among the various athletes' groups as regards Tanner stages, height and weight. The mean T and FAI values of the control group did not differ from those of the corresponding athletes group. Significant differences were observed among the groups regarding BMI, % body fat, T, SHBG, FAI and GH (p<0.05). T and FAI values in the WG group were significantly higher than the corresponding concentrations: a) in the AG group by 338 and 609%, p<0.05 and b) in the control group CG by 91 and 96%, p<0.05, respectively. The hormonal differences detected among the various groups of athletes must be attributed as much to the type of physical exercise and to developmental
factors as to the selection criteria used for the different athletic talents. The importance of the specificity of training stimulus in the hormonal adaptations of pre-pubertal sedentary subjects was demonstrated.
J Strength Cond Res. 2003 Feb;17(1):40-6.
Growth and anabolic hormones, leptin, and neuromuscular performance in moderately trained prepubescent athletes and untrained boys.
Tsolakis C, Vagenas G, Dessypris A.
Department of Physical Education and Sports Science, University of Athens, Athens 17237, Greece. Tsolakis.email@example.com
We investigated hormonal regulators of growth and development, leptin levels, body composition, neuromuscular performance, and the associations among them in trained prepubertal athletes (experimental group [EG]) and an untrained control group (CG). Informed consent was obtained from the children and their parents. Their maturation stage was evaluated according to Tanner's criteria. There were no differences between EG and CG in physical characteristics, body mass index (BMI), lean body mass, testosterone (T), sex hormone-binding globulin, free androgen index, growth hormone (GH), hand grip strength, and jumping performance. Leptin levels and percent fat of the EG were significantly lower than those of the CG (p < 0.05-0.005). Leptin levels were significantly correlated to body fat and BMI for both the EG and the CG (r = 0.51-0.79). There is little evidence that leptin has a positive effect on growth and anabolic factors. Sex hormone-binding globulin and GH may explain the variation
of leptin in athletes with low T (R(2) = 0.43) and in CG (R(2) = 0.35), respectively. Leptin seems to be a permissive factor for the onset of puberty, and the training background needs an optimal biological maturation to produce significant differences in muscle and power performance.
[PubMed - indexed for MEDLINE]