Which of the following is not a common cause of chronic back pain?

Regular stretching is not a common cause of chronic back pain because, in fact, it is often recommended as a preventative measure and a management strategy for back pain. Stretching helps improve flexibility, strengthen muscles, and maintain a proper range of motion in the joints, all of which contribute positively to spinal health.

On the other hand, disc degeneration, muscle strain, and heavy lifting are well-established contributors to chronic back pain. Disc degeneration can lead to herniated discs or spinal stenosis, both of which can cause persistent pain. Muscle strain typically results from overuse or improper lifting techniques, leading to discomfort and limited mobility. Heavy lifting, especially when done without proper technique, can place excessive stress on the spine and its supporting structures, often resulting in pain or injury. Therefore, while stretching focuses on promoting health and mobility, the other options involve risk factors that can lead to chronic back pain.