Injuries related to poor posture tend to be overuse injuries, which build up over a period of time. Slouched sitting for extended periods of time at a desk or in front of the TV can cause the shoulder joints to sit in a forwards position. This causes a muscle imbalance where the chest muscles are tight and the upper back muscles are weak. If you suffer with low back pain that developed slow and gradual with no history of trauma or overuse, the problem may be due to poor posture. Slumped sitting usually causes the arch of the back to flex or round and this places extra strain on the muscles and ligaments, which support the lower back. This results in muscle spasms and sometimes muscle strains.
For further information on how to improve your posture, read more.