Sitting down for too long during the day can harm your heart, even if you do plenty of exercise, experts have warned.
Spending more than 10-and-a-half hours sitting, reclining or lying down during daytime hours could increase the risk of dying from heart failure, a heart attack or stroke – even if you do the recommended levels of exercise, a study suggests.
Researchers from Massachusetts General Hospital analysed data from fitness trackers that captured movement over seven days for nearly 90,000 British people.
Overall, sedentary time averaged out at around 9.4 hours per day. The team then followed up on participants’ heart health around eight years later.
Analysis revealed that the chances of dying from heart failure, a heart attack or stroke during this period were minimal until a certain ‘threshold’ of sedentary time was reached.
They found that the risk of dying from these causes rose significantly in people who sat, reclined or lay down for more than 10.6 hours a day.
And this was also the case for participants who met the recommended 150 minutes of moderate-to-vigorous exercise per week.
Shaan Khurshid, co-senior author of the study, said: ‘Our findings support cutting back on sedentary time to reduce cardiovascular risk.
They found that the risk of dying from heart attacks, strokes and heart disease rose significantly in people who sat, reclined or lay down for more than 10.6 hours a day.
‘10.6 hours a day marked a potentially key threshold tied to higher heart failure and cardiovascular mortality.
‘Too much sitting or lying down can be harmful for heart health, even for those who are active.’
The team said future public health guidelines should stress the importance of cutting down on sedentary time, advising people to avoid more than 10.6 hours per day.
The findings were published in the Journal of the American College of Cardiology (JACC) and presented at the American Heart Association’s Scientific Sessions 2024.
In an accompanying comment piece Charles Eaton, director of the Brown University department of family medicine, said people tend to over-estimate how much exercise they do and under-estimate how long they are sedentary.
He said replacing just 30 minutes of excessive sitting time each day with any type of physical activity can lower heart health risks.
For example, adding moderate-to-vigorous activity cuts the risk of heart failure by 15 per cent and death from a heart attack or stroke by 10 per cent.
And even light activity, such as a gentle walk, reduced the risk of heart failure by 6 per cent and death from a heart attack or stroke by 9 per cent.
Harlan Krumholz, editor-in-chief of JACC, said: ‘This study adds to the growing evidence of a strong link between sedentary behaviour and cardiovascular health.
‘The findings strongly suggest that we need to get people moving to promote better health.’
