Hormonal responses to physical training in high-level peripubertal male gymnasts

Abstract

The effects of performing intensive training during growth remains controversial, with claims of negative effects upon growth and maturation purportedly due at least in part to a combination of hormonal disturbances and inappropriate nutrition. We examined the training-related responses of total testosterone (T), insulin-like growth factor-1 (IGF-1), cortisol (C) and diet in 16 peripubertal (pubertal stage <2) male gymnasts [mean (SD) age 10.5 (0.9) years, training 17.2 (5.6) h x week(-1)] and 17 controls [mean (SD) age 9.6 (1.2) years] over a 10-month period. Fasted, resting morning blood samples (0730-0900 hours) were taken from all children on Monday, Wednesday and Friday during a single week towards the end of each of three phases of gymnastics training: routine development (RD), precompetition (PC) and strength conditioning (SC). Serum concentrations of T, C and IGF-1 did not differ between the groups at any time. The ratio between IGF-1 and cortisol was significantly reduced in gymnasts relative to controls during RD and SC training (P<0.05), although no differences were detected for the T:C ratio. Diet did not correlate with any of the hormonal measurements, and no intergroup differences were found for the rate of growth in height. In summary, these results suggest that either the gymnastics training performed by these subjects was not intense enough to alter adrenal function, or that the gymnasts were well adapted to the training. In contrast, the reduction in the anabolic to catabolic balance represented by the IGF-1:C ratio is suggestive of a catabolic state, perhaps resulting from overstrain, insufficient recovery and/or inadequate caloric intake relative to energy output. While physical training during growth may induce a catabolic state, further research is needed to determine the biological significance of this finding, particularly with regard to growth and maturation.

Influence of training status and exercise modality on pulmonary O2 uptake kinetics in pre-pubertal girls

“…This age-related disparity may be related to a biological immaturity, such as a lack of testosterone Rowland et al 1994) or to an overload limitation, either due to the lower blood pressures present in children during exercise (Nottin et al 2002) or the shorter duration of training undertaken by children (Nottin et al 2004). Although training has been reported to increase testosterone and growth hormone levels from puberty onwards, no difference in the levels of these hormones has been shown pre-puberty (Daly et al 1998;Tsolakis et al 2003;Zakas et al 1994).…”

Preserved Bone Health in Adolescent Elite Rhythmic Gymnasts despite Hypoleptinemia

“…The normal level of IGF1 measured in our subjects, may partly explain the higher bone formation observed. Finally, the IGF1/C ratio that is suggestive of a catabolic state, resulting from overstrain, insufficient recovery and/or inadequate caloric intake relative to energy output [35] was not different between rhythmic gymnasts and, in spite of the negative energy balance. This lack of endocrine evidence of energy deficiency in the rhythmic gymnast group raises further doubt about whether the rhythmic gymnasts were actually energy-deficient.…”

Physical and pubertal development in young male gymnasts

“…The correlation between energy expenditure (MET/wk) and body fat percent suggests that more physical activity could result in higher energy requirements and therefore less energy stored, but without nutritional intake data no specific conclusions can be made. Although in the past diet was not correlated with serum concentrations of testosterone, IGF-I, and cortisol in peripubertal male gymnasts, a reduction found in their ratio of IGF-I to cortisol after periods of strenuous training is suggestive of a catabolic state, which may be partially attributed to an imbalance between energy intake and expenditure (6). Furthermore, the lower body fat percent without a difference in weight suggests an increase in lean body mass in response to training in our subjects.…”

“…In fact, it is possible that the decreased testosterone is a function of an increase in receptor binding, which would be a positive effect. Furthermore, the lack of a difference in growth rates, IGF-I, and diet between young male gymnasts and controls over a 10-to 18-mo period indicates that the short stature found in gymnasts may be due to selection bias rather than gymnastics training per se (6,7).…”