To cross your legs at the knee while sitting is almost second nature for some. As West Side Toast Masters highlights, it can even be an important type of communication, often indicating nervousness or submissiveness.

But you might want to find a new way to say “Yes, master” if new research indicating crossing of the legs to be harmful is true.

For one, as reported by the BBC, crossing your legs can put pressure on your leg’s peroneal nerve at the back of the knee. This can temporarily impair the sensation in your lower legs and feet.

Sitting cross-legged on the floor is even worse, as one Korean study found. In this case, sitting cross-legged on the floor for hours at a time can lead to peroneal nerve palsy, which leads to “foot drop,” where the front part of the foot and toes cannot be lifted.

You ain't gonna be smiling for long, kid...

You ain’t gonna be smiling for long, kid…

It can also cause increased neck and back pain, according to orthopedic physical therapist Vivian Eisenstadt. This is because it puts your hips in a torqued position, often leading to the rotation of a pelvic bone. The longer you sit in this form, the more pressure is put on your spine, increasing your chances of developing an issue.

“Days and weeks of doing this are one of the main reasons we have back and neck pain, as well as herniated discs,” Eisenstadt said to Yahoo Health.

As if all that wasn’t enough, sitting cross-legged can actually cause your blood pressure to go up, causing damage to your heart due to the blood that has to be pumped against gravity up to your heart.

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So, don’t sit like that.

How should you sit instead? This video from BuzzFeed has quite a few tips that’ll come in handy.