My body and my back love it when I perch at my desk.
And I don’t mean like a bird on a post.
Perching is active sitting on a surface so your knees are well below your hips.
You’re used to the normal height chair that puts the front of your thighs at a 90 degree angle to the front of your torso, and parallel to the floor. That is better than sitting in a chair that puts your knees higher than your hips and decreases that angle.
But the 90 angle can still be challenging.
Sitting on an a higher chair–think bar stool height–drops your knees down below your hips and opens up the angle to more like 120 degrees.
If you looked at yourself from the side you’d be half way between sitting and standing.
This maintains some of the lumbar curve (the gentle forward curve in the low back) that you have when standing but tend to loose when you sit at that 90 degree angle. The gentle interplay of forward and backward curves in the spine is one aspect of your anatomy that helps you be upright with ease.
Sitting up on a higher surface requires you to have a work surface that’s adjustable. That’s why I’m a big fan of (easily) adjustable height desks. I find however, that people are only thinking about using these desks for sitting in a normal height chair or standing.
Not somewhere in between.
That somewhere in between is the place to perch.