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Physical activity can reduce mortality risk caused by sitting for too long

Previous research demonstrated that among less active adults, the amount of time spent sitting is associated with an increased risk of mortality. A new study published by the American College of Cardiology has found that the negative impacts of sedentary behavior can often be eliminated through physical activity.

The researchers set out to investigate the relationship between sedentary behavior or physical activity and mortality. The team analyzed the effects of replacing sitting with standing, physical activity, and sleep.

Study lead author Dr. Emmanuel Stamatakis is a professor of Physical Activity, Lifestyle and Population Health at the University of Sydney.

“Previous studies have not considered that a 24-hour day is finite and an increase in any type of physical activity or sedentary behavior would displace another activity or sleep,” explained Dr. Stamatakis.

The investigation was focused on nearly 150,000 Australian men and women aged 45 years and older who reported on how many hours per day they spent sitting, standing, and sleeping. The individuals also reported the total time they spent walking or participating in moderate to intense physical activity.

On average, the participants were followed  up with after 8.9 years for all-cause mortality and after 7.4 years for cardiovascular disease mortality. The researchers found that higher sitting times of more than six hours per day were associated with higher all-cause and cardiovascular disease mortality risks. However, these risks were mostly found in those did not meet physical activity recommendations.

With the exception of those who sat more than 8 hours per day, meeting even the lowest requirements for physical activity eliminated the association with all-cause mortality risk.

“Our results support continued efforts to promote physical activity in those segments of the population that sit a lot for whatever reason,” said Dr. Stamatakis. “In the absence of some physical activity, merely reducing sitting times may be insufficient for better health.”

Replacing sitting with standing was associated with risk reduction in low sitters, but replacing sitting with physical activity was a much more reliable way to reduce mortality risk among high sitters.

“A possible explanation for this is that among the most sedentary participants, standing may not be sufficient for reducing health risks,” said Dr. Stamatakis. “Instead, substituting sitting for brisk walking may be a better option that is feasible by a majority of adults.”

The study is published in the Journal of the American College of Cardiology.

By Chrissy Sexton, Staff Writer

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