Final answer:
Continued poor posture while sitting, characterized by a rounded spine and increased thoracic kyphosis, is most likely to result in the development of a forward-head posture, shortening of anterior trunk muscles and connective tissue, and weakening of overstretched trunk extensor muscles, which are all connected to spinal curvature disorders.
Step-by-step explanation:
A person working in a sitting position for several hours displays a rounded spine with increased thoracic kyphosis. If this poor postural position is continued over time, it can lead to multiple issues:
- Forward-head posture development due to a compensatory mechanism for the imbalance caused by a rounded spine.
- Shortening of anterior trunk muscles and connective tissue, as poor posture can alter the normal length-tension relationship of muscles, leading to adaptive shortening.
- Weakening of overstretched trunk extensor muscles because these muscles are persistently lengthened and may become less efficient.
Thus, the most likely conditions to arise from such poor posture, given prolonged continuation, are indeed D. All of the above.