The nerves in our body always run on a low grade resting electrical system. As tissue is stimulated and or stressed, the electrical system in the nerves may increase its electrical levels. If the stress is alleviated, it will return to the normal resting level. If the stress continues or is amplified, then the electrical signal continues to rise. If the electrical signal reaches the alarm threshold, then danger signals are sent to the brain, and brain may interpret these signals as pain.
They also may misconstrue a pulling or stretch sensation as pain. They become fearful or anxious of these movements and when forced into them they have a much lower threshold and pain is elicited more quickly. This can become a vicious cycle until the individual avoids the movement or activity all together.