Physical activity and reproductive function in women.

The relationship between heavy physical stress and reproductive function in sportswomen has received comparatively little attention. In some young sportswomen an onset of menarche which is later than average has been found. Studies of menstrual rhythm in women who train hard have not given any decisive answers, but individual observations indicate a certain deficiency of ovarian function or delay in ovulation. The performance level may be lowered during the actual period of menstruation, but even here the evidence is poor. Whether or not modern methods of contraception such as the pill and intra-uterine devices have any influence on performance is an open question. There is no objective evidence that training is harmful during pregnancy, or that it causes problems in labour, neither does the experience of labour appear to influence later performance.