Author: Dr Michelle Harvie - October 6, 2021

Keep Moving Exercise Prevent Breast Cancer Charity UK

Prevent Breast Cancer researcher and acclaimed dietitian, Dr Michelle Harvie, looks into research that discusses the role of physical activity in breast cancer prevention.


A research paper written by Darryl Edwards and published in The Journal of Evolution and Health has purported that the promotion of physical activity is advisable and a vital component of cancer prevention. In other words, women who are more active are less likely to get breast cancer.

Consistent evidence linking physical activity to lower rates of breast cancer has accumulated over the past 25 years, however the reasons for this are not well understood. A prevalent theory is that physical activity aids the lowering of circulating steroid hormone levels. Dr Michelle Harvie seconds this notion, stating that women who exercise will have lower levels of hormones such as oestrogen and insulin which are both linked to cancer risk. These women are also likely to have better immune functions and perhaps increased Vitamin D levels if they exercise outdoors.

The cancer shielding effects are seen across women of all ages, including women with a family history and even high risk BRCA genes. However, Dr Harvie does note that one study in women with a BRCA mutation did not find that physical activity prevented breast cancer, but delayed the age of diagnosis by 10 years. In this study women who were active as teenagers were diagnosed at the age of 50, rather than 40 which was the case for inactive women.

Dr Michelle Harvie also states that “physical activity reduces the risk of five other types of cancers, including bowel and womb cancer. However, exactly how much and which type and intensity of exercise is less easy to pin down, as it is notoriously difficult to accurately assess people’s activity levels.”



The general recommended level of activity for health is to do at least 150 minutes of moderate intensity activity a week, such as brisk walking. This level of activity has been linked to lower rates of heart disease, stroke, diabetes and bowel cancer. It seems higher levels may be required to reduce breast cancer risk. These higher levels appear to be around 5 – 8 hours of brisk walking or 2.5 – 4 hours of vigorous intensity exercise like running per week.

Dr Michelle Harvie adds that activity is most cancer protective in women who are also a healthy weight, and that we should all promote physical activity alongside healthy diets and weight control, in order to reduce the rates of breast cancer.

Find out more about diet and lifestyle and The 2 Day Diet which was co-written by Dr Michelle Harvie.