Stand up for your heart

Thanks to a wealth of research about the cardiovascular benefits of exercise, there are guidelines about the amount and types of exercise people need to keep their hearts in good shape (see "A three-pronged approach to exercise" in the May 2025 Heart Letter). If you're working out for at least 30 minutes a day, that's great. But what if you spend the remainder of your waking hours mostly sitting in a chair or lounging on a couch? A new study explored the downsides of that habit — and how much downtime may put your heart in jeopardy.

"We've known very little about the potential consequences of sedentary behavior beyond the vague awareness that too much sitting is probably not good for you," says Dr. Ezimamaka Ajufo, a cardiovascular medicine fellow at Harvard-affiliated Brigham and Women's Hospital. So she and colleagues took a close look at how movement habits influenced heart disease risk in 90,000 people listed in the UK Biobank, a large database in the United Kingdom that began collecting health information in 2006.

Participants submitted a week's worth of data from a small wrist sensor that measured how much time they spent asleep, sedentary, engaging in light activity, or doing moderate-to-vigorous activity. Researchers then tallied the incidence of atrial fibrillation, heart attack, heart failure, and death from heart disease among the participants over the following decade.

People who sat more were more likely to have any of the four conditions, says Dr. Ajufo. "What was particularly interesting was that risk of heart failure and cardiovascular death was about 50% higher among people who were sedentary for more than 10.6 hours per day," she says. Even if you get the recommended 150 minutes per week of moderate-to-vigorous exercise, that may not be enough to reduce your heart disease risk if you're sitting too much. While the risk for atrial fibrillation and heart attack was mostly offset by routine physical activity, that wasn't the case for heart failure or dying from heart disease. The findings were published Feb. 11, 2025, in the Journal of the American College of Cardiology.

Why is sitting harmful?

Uninterrupted sitting has harmful effects on metabolism, leading your body to burn fewer calories and less fat. It can also cause blood sugar levels to rise, triggering the release of insulin, the hormone that regulates blood sugar. Over time, sedentary habits cause the body to become less sensitive to insulin. The resulting insulin resistance can progress to diabetes and also promotes inflammation, a key player in the buildup of fatty plaque inside arteries.

Studies in rats suggest that sedentary behavior may change the activity of dozens of genes, including the gene responsible for making lipoprotein lipase (LPL). This enzyme helps break down fat so it can be used for energy or stored in the body. When rats were prevented from moving, LPL levels decreased, a change that may also contribute to raising heart disease risk.

Researchers also speculate that even the simple mechanics of sitting still for too long may tax the heart and trigger short-lived increases in blood pressure.

What you can do

Start by paying attention to how much time you spend sitting each day. For many people, it's the time spent in front of a screen — a smartphone, computer, or television — that leads to uninterrupted hours of sitting. Try these suggestions:

• Set a timer. Set an alarm on your smart watch, smartphone, or computer, or get a regular kitchen timer and set it to go off every 30 to 60 minutes during the day when you tend to sit for long periods of time. When it rings, get up and walk around or do some simple exercise for a few minutes. March in place, swing your arms, or do some squats or leg lifts.
• Pace during phone calls. Whenever you're on the phone, stand up. Try to walk back and forth or in circles while you talk.
• Banish bingeing. Resist the temptation to sit through another episode of your favorite show or to keep channel surfing. After an hour in front of the TV, get up and do some household chores.
• Take the long way. Whenever you drive somewhere, park in a spot farther from the door to get in some extra steps.

"We're hoping that future guidelines and public health efforts will emphasize the importance of cutting down on excessive sitting, regardless of how active people are during the rest of the day," says Dr. Ajufo.

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