We all know exercise is good for the heart, but new research shows that sitting for too long can still be harmful—even for people who stay active.
A study published in the Journal of the American College of Cardiology and presented at the American Heart Association’s 2024 Scientific Sessions highlights how too much sedentary time increases the risk of heart problems and even death.
The study found that spending more than 10.5 hours a day sitting, reclining, or lying down is linked to higher chances of heart failure and cardiovascular (CV) death.
This is true even for those who meet the recommended exercise levels of at least 150 minutes of moderate-to-vigorous activity per week.
“Too much sitting or lying down can be harmful to heart health, even if you’re active,” says Dr. Shaan Khurshid, a cardiologist and co-author of the study.
“Our findings suggest that cutting back on sedentary time is key to reducing cardiovascular risk.”
While exercise guidelines focus on how much physical activity we need, they don’t say much about limiting sedentary behavior. This study sheds light on why that matters, as sitting and lying down make up a large portion of most people’s day.
The researchers studied 89,530 participants from the UK Biobank. The average participant was 62 years old, and more than half were women.
Participants wore wrist devices for seven days to measure movement, and on average, they spent 9.4 hours per day being sedentary.
After eight years of follow-up, researchers found that:
- 4.9% of participants developed atrial fibrillation (an irregular heartbeat).
- 2.1% developed heart failure.
- 1.84% had heart attacks.
- 0.94% died of cardiovascular causes.
The risk of heart failure and CV death increased significantly after 10.6 hours of sitting per day, creating a clear threshold for concern. While exercise reduced the risks of atrial fibrillation and heart attacks, it couldn’t fully offset the dangers of prolonged sitting for heart failure and CV death.
In an editorial accompanying the study, Dr. Charles Eaton from Brown University explained that wearable devices like accelerometers give more accurate data than people’s self-reports. He highlighted that replacing just 30 minutes of sitting each day with light activity can reduce heart failure risk by 6% and CV death by 9%. Moderate-to-vigorous activity is even better, lowering heart failure risk by 15% and CV death by 10%.
Dr. Harlan Krumholz of Yale University emphasized the importance of these findings: “This study adds to the growing evidence that we need to move more and sit less to improve heart health.”
If you’re spending long hours sitting at work, watching TV, or scrolling on your phone, experts recommend breaking up that time with movement. Even light activity, like standing, walking, or stretching, can help. Avoiding more than 10.6 hours of sedentary time per day could make a big difference for your heart.
While the study has some limitations, such as not knowing why or where people were sitting, the message is clear: Sitting less and moving more can lead to a healthier heart and longer life.
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