
This idea is called the "Gate Control Theory". The path of travel of the pain signals starts from the affected area, to the spinal cord and then ultimately to the brain. When the affected area is rubbed, other impulses also reach the brain via the same nerve. This clogs the pain signal and the pain impulse gets reduced. A study conducted in 2003 showed that massage worked better than acupuncture or spinal modification for persistent low back pain, reducing the need for painkiller by 36 percent.