Sitting for more than 10 hours a day is bad for your heart, even if you exercise

Spending too much time sitting can harm your heart healtheven in active peopleaccording to a study that links sitting more than 10 and a half hours a day to an increased risk of heart failure and death from cardiovascular disease, even among those who exercise regularly.

That’s the main finding of a study of 89,530 participants published in JACC, the journal of the American College of Cardiology, and presented at the 2024 Scientific Sessions of the American Heart Association. Spending more time sitting, reclining, or lying down during the day can be bad for your heart.

Insufficient physical activity is a known risk factor for cardiovascular disease, recalls the aforementioned college’s statement, which indicates that current guidelines recommend more than 150 minutes of moderate to vigorous physical activity per week to promote heart health.

However, study experts say exercise makes up only a small portion of overall daily activity, and current guidelines do not include specific guidance for sedentary behavior, which makes up a much larger portion of daily activity.

This study examined the amount of time spent sitting at the highest risk for cardiovascular disease, and examined how such behavior and physical activity jointly influence the likelihood of developing atrial fibrillation, heart failure, myocardial infarction, and mortality.

Among the 89,530 UK Biobank participants, the average age was 62 years and 56.4% were women. They sent data from a three-axis accelerometer on the wrist, which recorded movement for seven days; The average daily sedentary time was 9.4 hours.

Over an average of eight years of follow-up, 3,638 people (4.9%) developed atrial fibrillation, 1,854 (2.1%) had heart failure, 1,610 (1.84%) had a myocardial infarction, and 846 (0.94%) died.

The impact of sedentary behavior varied by outcome. The risk of atrial fibrillation and myocardial infarction increased gradually over time without significant change.

For heart failure and cardiovascular mortality, the increase in risk was minimal until sedentary time exceeded 10.6 hours per day, after which the risk increased significantly, “showing a threshold effect.”

In participants who completed the recommended 150 minutes or more of moderate-to-vigorous physical activity, the effect of sedentary behavior on the risk of atrial fibrillation and myocardial infarction was significantly reduced, but the effect on the increased risk of heart failure and mortality remained important.

“Future recommendations and public health efforts should emphasize the importance of reducing time spent sitting,” said Shaan Khurshid, a cardiologist at Massachusetts General Hospital and co-senior author of the study. “Avoiding more than 10.6 hours per day may be a realistic minimum goal for improving heart health.”

In an accompanying editorial commentary, Charles Eaton of Brown University’s Department of Family Medicine said that the use of wearable accelerometers has shown that self-reports significantly overestimate exercise and underestimate sedentary behavior.

Eaton noted that replacing just 30 minutes a day of excessive sitting with any form of physical activity can reduce heart health risks.