One of the biggest concerns facing women in sport is the effect of the menstrual cycle and oral contraceptives (the pill) on performance. The full article explains the issues of menstruation for female cyclists.

I know that many women riders can still remember the days of being exempt from school games during their period, as exercising then was considered unhealthy and unhygienic. Thankfully those days are over. Modern formulations of the contraceptive pill have minimal, if any, effects on performance and many athletes find them decidedly beneficial.

The increase in the number of women who are physically active has helped scientists understand the interaction between exercise and the menstrual cycle much better than ever before and it allows coaches to base their advice on fact rather than old wives' tales.

There is evidence to suggest that some types of training are more effective if carried out at certain times of the menstrual cycle. However, this research is not conclusive and there are so many individual differences that it is far better to find out what works best for you. Your body will respond better to training anyway if there is variety in your programme, so it's worth experimenting a little. For example, some riders find that back pain and stomach cramps mean long rides are not pleasurable during their period and so they prefer to concentrate on shorter, harder sessions, whereas other riders find the complete opposite... try both and see which is best for you!

Exercising during your period is not harmful and scientific research suggests there is no physiological reason for your period to affect your performance. However, from personal experience I know that changes to mental mood state can affect performance, as can physical effects of back pain and cramps. It is also important to realise that your undercarriage is more sensitive at this time and you may find long rides uncomfortable as well as impractical. On the plus side, the endorphins and other hormones produced through exercise can help improve mood state and stave off the chocolate cravings!
Many athletes choose to use the contraceptive pill for the convenience of lighter, more regular 'periods' as well as for the intended purpose. Again there is conflicting scientific thought on the effects of the pill on performance. There are now so many varieties on the market that most athletes can find a brand to suit them - although this may take some months, so it's best investigated during the off-season. Furthermore, the benefits of contraception, lower blood loss, controllable frequency of bleeds and the bone protective effects normally outweigh the downsides. As with any drug there are however, medical side effects and an individual's suitability for the pill needs to be discussed with her doctor.

Finally there is the question of missing periods. Athletic amenorrhoea is a real problem in some sports and even in cycling a small percentage of women finds themselves in this situation. You must see your doctor as soon as you have a problem and definitely if you miss three or more periods, or if your periods become irregular (oligomenorrhoea).
Lack of periods may indicate hormonal abnormalities, which can have a knock-on effect on bone density and ultimately on fertility. Often cutting back on the volume of training and improving the level and quality of nutrition can help but you must seek medical help. Similar problems can exist in young female riders who may find the start of their periods (menarche) is delayed. If you have any concerns in this area speak to a female friendly coach who should be able to help and advise.