Experts compared a lack of exercise to other well-known risk factors for heart disease, including a high body mass index (BMI), high blood pressure and smoking, and found that physical inactivity had the greatest risk.
The finding prompted the researchers to call for women aged 30 and over to be encouraged to engage in greater physical activity.
The study, published in the British Journal of Sports Medicine, examined the data from thousands of women taking part in the Australian Longitudinal Study on Women's Health. Researchers looked at smoking rates, prevalence of inactivity and high blood pressure and whether or not the women were obese.
After analysing mortality figures, they found that from age 30 until the late 80s, low physical activity levelswere among the key risk factors facing women.
The authors estimated that in Australia, where 12,000 middle-aged and 9,100 older women die from heart disease each year, the lives of around 2,600 women could be saved annually if women did 150 minutes of moderate-intensity activity each week.