Calling all couch potatoes! Sitting is hard on your kidneys.

British researchers asked over 5,000 volunteers to track the time they spent sitting. Then, doctors examined them for signs of kidney disease. The result: The people who sat the most had kidneys that were in the worst shape even after they took into account factors like smoking, age, gender, and body-mass index along with blood pressure, what medications they were taking, and how many hours of exercise they got a day.

Unfortunately, just 8 hours of sitting – which is pretty common for office workers – increases your risk of kidney disease by 40 percent. Researchers aren’t sure whether sitting causes kidney disease or whether people with bad kidneys are more likely to spend more time sitting. But since spending long periods of time in a chair has been linked to other chronic diseases – like type 2 diabetes – researchers believe we’re just not built to spend all day sitting down.

Does this mean you should give up your desk job? Kidney expert Dr. Jeffrey Berns says, “No.” But it does mean that for every hour you sit, you should get up and move around for at least 5 minutes. Because research shows that short, frequent bouts of activity are more effective at preventing the health problems blamed on prolonged sitting than a daily workout at the gym.