Regular exercise may not offset health risk of sitting too much

Exercise and physical activity are great for heart health. But the benefits can be wiped out — even for those who exercise — if someone sits too much during the rest of the day. That after-work workout may not be as effective as people think.
There’s a threshold of sedentary behavior that increases the risk of heart disease and death, per a new study by researchers at Massachusetts General Brigham, published in the Journal of the American College of Cardiology.
“Many of us spend the majority of our waking day sitting, and while there’s a lot of research supporting the importance of physical activity, we knew relatively little about the potential consequences of sitting too much beyond a vague awareness that it might be harmful,” lead author Dr. Ezimamaka Ajufo, cardiology fellow at Brigham and Women’s Hospital, said in a news release on the research.
“Sedentary risk remained even in people who were physically active, which is important because many of us sit a lot and think that if we can get out at the end of the day and do some exercise we can counterbalance it. However, we found it to be more complex than that.”
The study involved 89,530 participants, mostly in their 60s, in the UK Biobank study who were provided accelerometers for a week to measure their activity and sedentary time and then were followed up for almost a decade to see what happened to them. Researchers found that being sedentary more than 10.6 hours a day was particularly associated with greater risk of heart failure and cardiovascular-caused death. People who sat that long also had greater risk of atrial fibrillation and heart attack, though not to the same degree.
The link to heart failure and cardiovascular-related death held even among those who met the recommended 150 minutes a week of moderate to vigorous physical activity. Regular exercise can mitigate the risk of atrial fibrillation and heart attacks, but it only partially counters the extra risk of heart failure and cardiovascular death.
Sedentary behavior doesn’t count time spent sleeping; it’s defined in the study as low energy expenditure while awake and can include sitting, lying down or reclining.
In the release, the researchers said they hope the findings will help people realize they have to do more than exercise. They have to move around during the day, to “leverage movement behaviors to improve cardiovascular health,” as well, in the words of Dr. Patrick Ellinor, a cardiologist and co-director of the Corrigan Minehan Heart Center at Massachusetts General Hospital.
The researchers said they plan in the future to study how sedentary behavior impacts other diseases, as well.