Q: Can too much exercise affect my chances of falling pregnant?

Easy does it: There can be an adverse impact on fertility as a result of intensive exercise.

Easy does it: There can be an adverse impact on fertility as a result of intensive exercise.

A: We know that regular exercise is beneficial for our health, not only for reducing a person's risk of developing diseases like heart disease and some cancers, but also for our mental health and wellbeing.

We have seen in studies that overweight and obese women with polycystic ovary syndrome (PCOS) have seen improvements in the regularity of their menstruation and ovulation cycle from integrating regular exercise into their lives.

However when it comes to the success of IVF cycles vigorous exercise such as running or cycling, performed for greater than five hours per week, has been associated with a 32 per cent reduction in pregnancy rates.

I find this difficult to deal with as a doctor, because we know that people who exercise intensively are lean and will live longer - this kind of exercise is very good for health - but for pregnancy and actually conceiving it seems to be adverse.

It makes evolutionary sense. If you think about the kind of environment a woman would be in if she was needing to exercise intensively throughout evolution, it was almost certainly a war or famine type situation. So that's why we are seeing that there has been this adverse impact on fertility as a result of intensive exercise.

Moderate exercise doesn't really pose a problem. Walking is quite alright but it's the intensive exercise that seems to be a problem.

Men's fertility isn't affected as much by vigorous exercise, but it has been found that those exercising, particularly cycling, for 20 hours per week or more have lower sperm counts. In fact male cycling may be adverse for fertility. There has been speculation about that perhaps the bike saddle places pressure on the perineum, or it could be scrotal warming.

The thing about exercise is it's something that's modifiable, and therefore important. Many people can't change their age, for instance, which has an effect on fertility. You can't change if you're running out of eggs or at risk of an early menopause. But exercise is something that you can change and that's why it's very important to understand its impact on fertility.

How should I be exercising?

The Australian exercise guidelines for adults recommend a minimum of 150 minutes of moderate activity like walking or dancing each work or 75 minutes of vigorous activity (or a combination of both) each week, plus muscle strengthening activities on two days per week.

Being both overweight and underweight can affect fertility, and both men and women can increase their fertility by maintaining a healthy weight through appropriate diet and exercise.

When trying to conceive 30 minutes per day of light or moderate exercise is recommended, and can be through activities such as yoga or brisk walking, and even incidental movement such as taking the stairs or playing in the backyard with kids.

Vigorous exercise to avoid can include things like running, playing team sports and tasks that require heavy lifting or carrying.

The Australian and Victorian governments have produced the Your Fertility website which contains resources for helping you understand how to improve your chances of conceiving.