Delayed age of menarche of athletes

To the Editor.— It is my fear that the conclusion of Frisch and colleagues (1981;246:1559), based on data that are derived from a small and seemingly unusual sample, may cause undue concern and worry by children, parents, and coaches. Indeed, the conclusion that training before menarche will delay menarche has been widely disseminated. There are thousands of premenarcheal girls engaged in sports training, and this questionable conclusion can have a negative impact on sports for girls. The conclusion is based on a small sample, 12 swimmers and six runners, who began training before menarche. Correlation analysis indicated a relationship between training before menarche and the age at menarche. It indicates only a relationship between the two variables, but does not indicate a cause-effect relationship. It could well have been that the young women took up training because of their delayed maturation rather than the training causing late maturation. If one