Sport training and the growth and pubertal maturation of young athletes.

Growth and pubertal maturation of youth athletes are overwhelmingly within the broad range of normal variability. These include many successful male athletes who mature earlier than average, and many successful female athletes, especially in the "aesthetic" sports (artistic gymnastics, ice-skating, ballet) and distance running, who mature later than average. Artistic gymnasts generally receive the most attention, but their growth and maturation characteristics fall largely within the physiologic range and are indistinguishable from short, late maturing girls. It is difficult to ascribe causality to intensive training for sport as a factor in the later pubertal maturation of heavily training athletes. The alterations in hypothalamic-pituitary function for the GH/IGF-I and gonadal axes are likely appropriate for the stage of adolescent maturation. The selection and sorting processes for elite sport, including ballet, need critical evaluation. If intensive training is a factor affecting growth and pubertal maturation, its effects must be partitioned from (a) other factors known to influence these biological processes, and (b) other components of the overall sport training environment before causality can be established. Other factors which play an indeterminate role include: genetics/epigenetics, stress, psychosocial interactions, family environment and caloric intake, among others. These factors together with the energy expenditure of intensive training may influence the growth and pubertal maturation of some adolescent athletes. The effect is not necessarily attributable to training per se; rather, it is likely embedded in the elite sport training environment which is essentially an adult dominated enterprise.