Physical inactivity in women aged 30 years and older has a greater impact on the risk of developing heart disease than any other major risk factor, according to an Australian study published today in the British Journal of Sports Medicine.
Wendy Brown, Ph.D., professor in the Centre for Research on Exercise, Physical Activity, and Health at the University of Queensland, Australia, and her fellow researchers, found that up to age 30 years, smoking was the most important contributor to heart disease in Australian women, but from age 30-80 years, physical inactivity was the top risk factor.
© shutterstock.com
For women over 30, lack of physical exercise had a greater role in developing heart disease than any other risk factor.
The researchers looked at the population attributable risk of ischemic heart disease in adult Australian women. They looked at four risk factors: excess weight (high body mass index); smoking; high blood pressure, and physical inactivity.
They based their estimates on the four risk factors’ prevalence in the Australian Longitudinal Study on Women’s Health, which has tracked the long-term health of 32,154 women born in 1921-1926, 1946-1951, and 1972-1978, since 1996.
The researchers found that smoking prevalence fell from 28% in women aged 22-27 years to 5% in those aged 73-78 years. However, the prevalence of inactivity and high blood pressure increased from age 22-90 years, and weight gain increased from age 22-64 years, but dropped in older age (Br. J. Sports Med. 2014 May 8 [doi:10.1136/bjsports-2013-093090]).
The researchers used a mathematical formula known as population attributable risk (PAR) to define the proportion of disease that would disappear if exposure to a specific risk factor were eliminated.
They found that relative risks for all four risk factors declined with age, but prevalence of physical inactivity, high BMI, and high blood pressure increased with age, while smoking prevalence decreased.
Overall, the average PAR for physical inactivity was 33% in the middle-age group and 24% in the older-age group. Specifically, the PAR for physical inactivity increased dramatically over time from 65% in women aged 73-78 years to 81% in women aged 85-90 years.
The study found that 1,261 middle-age and 9,151 older women die from heart disease every year. With increased physical activity in both age groups, the number of deaths could be reduced by 2,612 per year.
The researchers recommend to continue smoking cessation programs among younger women, and to promote physical activity in women of all ages. They also recommend at least 150 minutes of moderate activity per week for women aged 30-90 years who are currently inactive.
Dr. Carl "Chip" Lavie, medical director of cardiac rehabilitation and the exercise laboratories at the Ochsner Heart and Vascular Institute, New Orleans, says he is impressed with the study and supports its recommendations for increased physical activity.
"This is a very important study that emphasizes the fact that physical inactivity is probably the leading threat to health in the U.S. and most of the Western world, and it is clearly the case in Australia," he said.
The study was sponsored by the Australian Government Department of Health and Ageing. The investigators had no competing interests.