We’ve all heard that sitting too long is bad for you. We’re not evolved to do it, it can undermine our exercise gains, it causes dead butt syndrome. Sitting might not quite be “the new smoking,” but too much of it can still shorten your life.

“Sitting is actually aging you faster,” said Katy Bowman, a biomechanist and author of “My Perfect Movement Plan.” Whether it’s bone or joint health, muscle mass or energy level, she added, “a lot of what you perceive as aging is going to be heavily influenced by your sitting time.”

And we spend a lot of time sitting. Numbers vary around how much average Americans sit per day, but it may be as long as 9 1/2 hours. Studies suggest women sit less than men do, but most agree we all sit more than previous generations did.

The consequences can be serious. A study published at the beginning of the year followed 480,000 people in Taiwan older than 13 and found those who sit most of the work day had a 34% higher risk of dying from cardiovascular disease than those with less sedentary jobs did — and a 16% higher risk of mortality overall.

One way to lower the risk, the authors wrote, was to add 15 to 30 minutes of physical activity per day to your existing routine. Other studies go further, suggesting sedentary people need to double the standard weekly exercise recommendations.

“The bottom line is that too much sitting is a big new health risk,” said Neville Owen, a senior scientist at the Baker Heart and Diabetes Institute in Melbourne, Australia.

Here’s what you need to know and how to mitigate your time in the chair.

Why is sitting so bad?

Put simply, uninterrupted sitting is bad for your heart, joints, muscles, metabolism and mental health.

The American Heart Association notes that prolonged sitting raises the risk of developing heart disease or stroke, even for those who exercise regularly. It can take as little as 30 minutes of uninterrupted sitting to affect how blood vessels function. And the longer you sit, the higher the cardiovascular risks, especially if you are sitting for more than 10 hours.

Sitting for extended periods has also been linked to lower back pain. Small studies suggest the height of your lumbar disc might be compressed after sitting more than four hours without interruption.

Furthermore, your large leg and gluteal muscles can stop activating after just 30 minutes of sitting, Owen said. Over time, they can weaken and cause back or knee pain.

Sitting also doesn’t burn much energy. Over time, a sedentary lifestyle can affect your ability to regulate blood sugar and break down fat, potentially leading to weight gain and Type 2 diabetes. American workers today burn about 100 fewer calories per day than they did 50 years ago. That’s roughly equal to 30 minutes of walking, said Thom Rieck, an exercise specialist at the Mayo Healthy Living Program in Rochester, Minnesota.

Lastly, sitting affects mood and cognition, increasing the odds of depression and anxiety.

How to get off your butt

If you sit for work, you have to be more active.

The fact is that if you sit a lot, the recommended 150 weekly minutes of moderate aerobic activity and strength training may not cut it, said Geoffrey Whitfield, an epidemiologist at the Centers for Disease Control and prevention. The more you sit, the more exercise you need. Some evidence suggests tripling that amount, to about 60 minutes per day, Whitfield added.

Set a timer at work. If you can’t add that much movement to your day, try adding small bouts, spread throughout the day. Brian Cleven, a clinical exercise physiologist in Marinette, Wisconsin, recommends working some exercises into your day at your desk. Try 10 to 15 repetitions of pointing and flexing each foot, seated calf raises and marching in place. Or try a quick exercise snack.

He suggests doing something every hour or perhaps exercising the lower body one hour and the upper body the next. Even better, he said, try to elevate your heart rate by taking a two- to five-minute walk every hour or walking up and down a set of stairs.

Standing desks aren’t a cure-all. Working at a standing desk expends more energy than sitting but can cause pain as well. The key is regular movement whether seated or standing, said Bethany Barone Gibbs, an epidemiologist based in Pittsburgh with the American Heart Association.

If nothing else, try fidgeting. If you can’t get up — say, during a long car drive — at the very least you should change your body position, ideally every 15 to 30 minutes, Dr. Barone Gibbs said. You can do this with small, subtle movements, like fidgeting by tapping or jiggling your feet every few minutes.

Try adjusting your leg, pelvis and spine positions, Bowman said. “Read your email with your arms stretching overhead or while twisting your shoulders to the right and left,” she suggested. Or alternate between doing 30 minutes of work standing and 30 minutes seated.

But you can’t fidget your way to good health. To avoid the adverse effects of a sitting-heavy lifestyle, add more movement breaks and more exercise to your daily routine, Whitfield said.