This is the most common complaint among people who sit for a living, and it is almost never a back injury. It is a postural endurance problem: the muscles holding your shoulder blades in place get asked to work statically for eight hours, and they fatigue.
What usually causes it
- Static loading. The muscles are not moving; they are holding. That is far more fatiguing than movement.
- A stiff thoracic spine. If the mid-back does not rotate or extend, the surrounding muscles take the strain instead.
- Rounded shoulders, which lengthen and weaken the muscles between the shoulder blades while the chest tightens and pulls forward.
- Screen and desk setup — laptop too low, monitor off to one side, chair too far from the desk.
The chest connection
Counter-intuitively, tight pectorals at the front are frequently what makes the upper back ache at the back. They pull the shoulders forward, leaving the mid-back muscles permanently over-stretched and working against them. Treating only the sore side of the body misses half the problem.
What treatment involves
Releasing the tight structures front and back, mobilising a stiff mid-back, and settling the trigger points — which usually gives immediate relief.
Then the boring, effective part: strengthening the mid-back, and fixing the setup that caused it. Otherwise it returns by the following week.