Pubertal Maturation, Hormonal Levels And Body Composition In Young Gymnasts And Age-matched Controls

Abstract

Puberty is characterized by large hormonal changes, resulting in both physical and sexual maturation. Intense training and low body fat has been found to delay the onset of puberty in females by altering normal hormonal development. In males, despite evidence that physical activity can also result in hormonal changes, intense gymnastics training has not been associated with changes in the onset of puberty, if body composition is within normal range. PURPOSE To assess sexual maturation, hormonal levels, and body fat among competitive male and female Canadian gymnasts and age-matched controls. METHODS The gymnastics group, comprised of 21 male (13.3 ± 0.3y) and 18 female gymnasts (13.4 ± 0.2y), was compared to 24 age-matched male (13.5 ± 0.3y) and 24 female (13.9 ± 0.1y) controls. Sexual maturation was self-assessed using the Tanner Scale. For the male subjects, testosterone levels were determined from saliva samples. For the female subjects, progesterone and estradiol (17-β) were measured from blood samples. For menstruating subjects, age at menarche was reported and blood draws were performed twice: in the follicular and luteal phase of the menstrual cycle. Relative body fat (%BF) was assessed using bioelectrical impedance analysis. RESULTS There were no significant differences between the male gymnasts and controls in salivary testosterone (43.3 ± 5.8 vs. 38.2 ± 4.1 pg ± ml−1), genital development (stages: 3.2 ± 0.2 vs 3.5 ± 0.1) or pubic hair development (stages: 3.5 ± 0.1 vs. 3.6 ± 0.1). Male gymnasts were similar in size, but had significantly (p≤0.05) lower %BF than the controls. Female gymnasts were significantly (P≤0.01) smaller, and had significantly (P≤0.01) lower body fat than female controls. Twenty-one female controls and one gymnast were menarcheal, with the average age at menarche being 12 ± 0.1y for the controls, and 13 for the menarcheal gymnast. Serum estradiol and progesterone levels for the pre-menarcheal gymnasts were similar to those measured in the controls during the follicular phase, which were significantly lower (P≤0.01) than those measured during the luteal phase. Breast development was delayed in female gymnasts compared to controls (stages: 2.7 ± 0.2 vs 3.8 ± 0.1), while the difference between the groups in pubic hair development did not reach significance (stages: 3.1 ± 0.2 vs 4.0 ± 0.2). CONCLUSION While the intense training by the young male gymnasts resulted in a decreased %body fat, there was no apparent alteration in the timing and extent of their physical and pubertal development. On the other hand, a delayed menarche, reduced physical and sexual maturation, and a low %body fat were found in the females engaged in gymnastics training.