If you slouch long enough, especially without support, it will hurt.

Good posture involves the muscles of the abdomen and hips to support the spine and hold the torso in an upright position.

When we are slouching, we aren’t engaging those muscles. So, I’m the short term, any t length of your back will start to ache from the strain of sort of hanging between your hips and shoulders.

In the long term, the muscles we should be using become weak and the poor posture causes damage to the spine, causing pain as our bodies rely more and more on the spine itself to hold us upright, when the meat Fram around the spine is supposed to be doing most of the work.