Answer:
The tight and stiff muscles in the body results in the nerve constriction. These nerve constriction takes place in the spinal cord of the body.
The nerve constriction leads to the poor blood circulation in the whole body and it results in pain the back.
The stiffness of the muscles can be cured by regularly exercising. Stretching and warming of the body helps in maintaining the flexibility of the muscles and better blood flow.
This will make the body flexible and free from pain.