People with back pain need to exercise as much as everyone else, but running is usually a poor choice of activity. The bones of your spine are located one on top of the other, separated by pads called discs. Bones are much harder than discs, so when spinal bones are compressed and move closer together, they can flatten the discs like pancakes. Since the discs are then shorter, they have to go somewhere else, so they widen and press on the nerves near them, causing pain. This is called a herniated disc. Anything that presses the bones closer together squashes the disc further and usually makes it hurt more. During running, the force of the foot striking the ground is transmitted up the leg to the back, which can compress the discs and cause pain.
The best sports for people with back pain are those that do not hurt when you do them. Riding a bicycle, walking slowly and swimming do not exert a jarring force on the discs to compress them, so these exercises are recommended for people with back pain as long they don’t hurt while they exercise. Doctors often recommend special exercises to flatten the lower back, strengthen the belly muscles and stretch the lower back muscles. The key to exercising when you have a compressed disc is to stop exercising when you feel pain. You may need to try several different activities to find the right one for you.