Studies have shown that all women are likely to reduce their risk of breast cancer with regular physical activity but some subgroups seem to benefit more than the others.

Postmenopausal women and women with a normal body mass index (BMI) were found to have the greatest risk reduction with physical activity. Different activities were found to have different influence in the risk reduction. Recreational physical activity cut the risk of breast cancer to a much greater extent than work-related activities did.

Researchers from Canada and Australia decided to examine how the timing, type, and level of physical activity affect the breast cancer risk. Seventy-six percent of all the studies done indicated that there was an anti-breast cancer effect for increased physical activity, with typical risk reductions of 25% to 30%. They also found evidence of a dose-response effect, which means more exercise correlated to more benefits.

In regards to activities, recreational activity, vigorous activity, and lifetime or later life activity showed the strongest reductions in breast cancer risk.

Postmenopausal women, women with a normal BMI, non-white women, women who have given birth, and those without a family history of breast cancer are those who benefit the most from exercising in regards to diminishing breast cancer risk.

Further studies will clarify the biological mechanisms behind the association between physical activity and reduced breast cancer risk especially with regard to the type, duration and intensity of activity as well as explain the differences in population subgroup effects.