Back pain from desk work is extremely common and the standard advice – sit up straight, buy an ergonomic chair – has weaker evidence than most people assume.
What the research suggests
No single posture has been shown to prevent back pain. Studies looking for a relationship between specific sitting postures and pain have produced inconsistent results.
What does show up consistently is duration. Staying in any one position for long periods is associated with discomfort, and the specific position matters less than the not moving.
The practical implication
The best posture is the next one. Changing position regularly – shifting, standing, walking for a minute – does more than getting any single position right.
That is why standing desks help some people and not others: standing still for hours has its own problems. Alternating helps.
What does help
Movement breaks, even brief ones, at intervals of half an hour or so.
General physical activity outside work hours, which has reasonable evidence for both preventing and reducing back pain.
Strength work, particularly for the trunk and hips, though the mechanism is less about core stability than the popular framing suggests.
Equipment
A chair that allows several comfortable positions is more useful than one that enforces a single correct one. Screen at a height that does not require looking down for hours. These help and they are not the main factor.
When to see someone
Pain that radiates down a leg, numbness, weakness, or any change in bladder or bowel function needs medical attention rather than an article.
This is general information and persistent pain should be assessed by a professional.