Too much sitting hurts the heart

New study shows that being sedentary increases the risk of the most common types of heart disease, even among those who get enough exercise

Fitting in a workout after a long day of sitting at a desk might not be enough to compensate for the impacts of sedentary behavior on the heart. Investigators from Mass General Brigham, found that excessive sedentary behavior (waking activity with low energy expenditure while sitting, reclining, or lying down and not including hours spent sleeping at night) was linked to increased risk of heart disease, especially heart failure and cardiovascular death, and that these risks could be significantly reduced by substituting sedentary time for other activities. They also found that meeting guideline levels of moderate-to-vigorous physical activity may be insufficient on its own to reduce cardiovascular risk if one is also sitting too much. Their results are 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,” said lead author Ezimamaka Ajufo, MD, a cardiology fellow at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system. “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.”  

Ajufo’s team, which included researchers from across Mass General Brigham, analyzed one week of activity-tracker data from 89,530 individuals from the UK Biobank prospective cohort. They looked at associations between daily time spent sitting and the future risk of four common cardiovascular diseases: atrial fibrillation, heart attacks, heart failure, and death from cardiovascular causes. The team used a machine learning algorithm to classify sedentary behavior. 

They found sedentary behavior was associated with higher risks of all four types of heart disease, with a marked 40-60 percent greater risk of heart failure and cardiovascular death observed when sedentary behavior exceeded 10.6 hours a day (not including hours spent sleeping). Many of the negative effects of sedentary behavior persisted even among those individuals who achieved the guideline-recommended >150 minutes of moderate-to-vigorous physical activity per week. For example, although the study found that the risk of atrial fibrillation and heart attacks could be mostly eliminated by engaging in physical activity, the excess risk of heart failure and cardiovascular death could only be partially offset by physical activity.  

“Our data supports the idea that it is always better to sit less and move more to reduce heart disease risk, and that avoiding excessive sitting is especially important for lowering risk of heart failure and cardiovascular death,” said co-senior author Shaan Khurshid, MD, MPH, an electrophysiologist and faculty member in the Telemachus And Irene Demoulas Family Foundation Center for Cardiac Arrythmias at Massachusetts General Hospital, a founding member of the Mass General Brigham healthcare system.  

The research team hopes these findings will help inform future guidelines and public health efforts. They would like future prospective studies to test the efficacy of public health interventions that help people reduce the number of hours they spend being sedentary and see how that affects cardiovascular health. Next, they plan to extend this research to investigate the impacts of sedentary behavior on a range of other diseases and for longer spans of time. 

“Exercise is critical, but avoiding excessive sitting appears separately important," said co-senior author Patrick Ellinor, MD, PhD, a cardiologist and co-director of the Corrigan Minehan Heart Center at Massachusetts General Hospital. "Our hope is that this work can empower patients and providers by offering another way to leverage movement behaviors to improve cardiovascular health.”