Abstract
Objective : The purpose of this study was to investigate muscle strength and skeletal age in trained and untrained pubertal boys and its relationship to the levels of Testosterone (T), Growth Hormone (GH) and Procollagen (PICP). Methods : Both the exercise and control groups consisted of 24 (mean 12.91, sd = 0.63) and 17 (mean 12.91, sd = 0.48) year old boys, respectively. The exercise group (EG), in addition to school activities, participated in a rowing training program for six months (rowing technique, strength & aerobic exercises, 60 min/day, three days/week). The control group (CG) only participated in the school physical education program, two to three times/week. Hormonal concentrations were measured by radioimmunoassay techniques. Venus blood samples were taken at rest from both groups. Results : Testosterone was increased in both groups (p<0.001). Significant differences were found within groups in T before training (p<0.01) There was an increase of PICP in EG after training (p<0.01). Differences on GH were observed before the training period in both groups (p<0.01). Both groups significantly differed in upper and lower limbs strengths. Significant correlation was found between PICP and skeletal age in both (p<0.05 and p<0.02, respectively) Conclusions: The gains in muscle strength in both groups may partly be explained by the increase in the concentrations of hormone levels and the changes in body size. Key words : skeletal age, muscle strength, anabolic hormones, rowing
Highlights
Participation in sport attracts many young people for a variety of reasons
There have been studies investigating hormone concentrations referring to hormonal levels before and after a training program and a competitive effort, or throughout the different phases of a training season
Significant differences were observed in both groups during the study period regarding skeletal age (p=0.001), height (p=0.001) and body weight (p=0.001)
Summary
Participation in sport attracts many young people for a variety of reasons. Rowing is a demanding physical and mental workout. Young people can develop teamwork, unselfishness and initiative. It is well known in the world of sport sciences that the potential of physical training is related to hormones (Mero et al, 1990, Eliakim and Nemet, 2013, Nemet et al, 2012, Ramson et al, 2012). Hormones are related to the changes of body constitution, distribution of fat tissue and muscular strength (Rogol, 1994). Growth Hormone and T are both anabolic hormones, with T contributing to growth and function of reproductive tissues and to the increase of muscle and bone mass, and GH, being essential for the growth and the development of bones, liver and other organs. There have been studies investigating hormone concentrations referring to hormonal levels before and after a training program and a competitive effort, or throughout the different phases of a training season
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