You feel it in your low back. By 2pm it is a dull ache across the belt line, and by the end of a long meeting day you are shifting in your chair every few minutes.
Your back is where you feel it. It is rarely where it started.
The hip joint is built to rotate. When you sit ten hours a day, the joint spends that entire time in one fixed position, and the tissue around it stops offering rotation because nothing asks for it. Then you stand up and move. Every step, every stair, every time you reach for something behind you, your body needs rotation from somewhere. If the hip will not give it, the lumbar spine gives it instead.
The lumbar spine is not built for rotation. It is built for stability. Ask it to rotate a few thousand times a day and it will tell you about it.
How I check this
I test hip internal rotation on both sides, passively, with you lying down so you cannot compensate. Most desk-bound clients I see are well short on at least one side, and often that side matches where the back pain sits. Then I check whether your spine is doing the work instead, by watching what your ribs and pelvis do when I ask for rotation.
What we do about it
Restore the rotation at the hip first. Then load it, so the range you gained holds under weight. Then, and only then, train the spine to stay stable while the hips move.
What we do not do is treat the back. Massage, heat and stretching the low back all feel good for about a day, because they address the tissue that is complaining rather than the joint that caused it to complain.
“Armaan doesn't just train you, he figures out what's actually wrong first.”
One client, a director in his forties, came to me after two years of managing back pain. His hip had almost no internal rotation on the right. Four months later the back pain was gone and it has stayed gone, because we fixed the thing that was producing it.
Try this yourself
Sit on the floor, one leg bent in front of you at 90 degrees, shin across your body. If that position is impossible on one side and fine on the other, you have found something worth testing properly.