Certain risk factors – such as excess weight, smoking and high blood pressure – are known to increase lifetime risk of developing heart disease in women. But now, research published in the British Journal of Sports Medicine suggests that, from age 30, physical inactivity has the biggest impact on this risk in women.

The researchers used data on 32,254 participants in the Australian Longitudinal Study on Women’s Health, which tracks the long-term health of women born in certain spans of time between 1921 and 1978.

In the US, heart disease is the leading cause of death, and the Centers for Disease Control and Prevention (CDC) warn that people of all ages and backgrounds are at risk for the condition.

According to the American Heart Association (AHA), more than 1 in 3 women in the US is living with cardiovascular disease (CVD); this includes nearly 50% of all African-American women and 34% of white women.

For this latest study, the researchers wanted to compare estimates of the main four risk factors of heart disease:

The team notes that these four risk factors are responsible for over half the global prevalence of heart disease, the leading cause of death across high income countries.

They employed a mathematical formula used to assess the proportion of disease in a specific population that would vanish if exposure to a certain risk factor were removed.

Data from the Global Burden of Disease study were also used and applied to the Australian women who took part in the study.

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Get moving: researchers found low levels of physical activity had the greatest impact on women’s heart disease risks.

The investigators observed that smoking prevalence fell from 28% in women 22-27 years old to 5% in those between the ages of 73 and 78.

However, inactivity prevalence and high blood pressure increased across their lifespans, from age 22 to 90, and overweight prevalence increased between the ages of 22 and 64, declining after those ages.

The team then combined prevalence with relative risk data – which reveals the likelihood that a woman with a specific risk factor will develop heart disease, compared with a woman without that risk factor.

After combining this data, the researchers observed that, until the age of 30, smoking had the greatest influence on heart disease risk.

Between the ages of 30 and 90, however, low physical activity levels had the greatest effect on higher levels of population risk, compared with any of the other risk factors, the team found.

The World Health Organization (WHO) recommend that all adults get 150 minutes of moderate intensity physical activity each week, and the researchers say if every woman between 30 and 90 were to reach this recommendation, then more than 2,000 middle-aged and older women’s lives would be saved in Australia each year.

Based on their results, the researchers say the effect of different risk factors on chances of developing heart disease change throughout a woman’s life.

They add:

”Our data suggest that national programs for the promotion and maintenance of physical activity, across the adult lifespan, but especially in young adulthood, deserve to be a much higher public health priority for women than they are now.”

Though they note that reducing smoking in young women is important, more focus should be put on keeping physically active; the main focus has been on obesity and BMI, they say.

Medical News Today recently reported on a study that suggested people who are obese by the age of 25 have a much greater risk of being severely obese after the age of 35.