Soft cushions called discs act as shock absorbers between the bones. The nerves run through the holes in the center of the vertebrae and branch out to your body. The bones, muscles, ligaments, nerves, or discs can cause back pain. This normally produces a lot of pain. Discs can degenerate or lose their shape and support, or they can bulge or rupture.
Muscles can fatigue and weaken, or become inflexible.
A weak abdomen cannot help support your back. Obesity puts an additional stress on the back. Ligaments can be over-stretched and cause the bones to lose their support. Poor posture, incorrect body mechanics, stress, inactivity or overexertion can lead to back pain. Good posture is necessary to keep the bones, nerves, muscles, ligaments and discs working well together.