Heat dissipates through the disk. Three things can occur. A crack can be sealed shut. The next is destruction because of the heat of fine nerve fibers that penetrate the outer one-third of the disk. It is a treatment only for back pain and only for patients failing to respond to all other conservative measures.
Traction can, in fact, reduce pain and the displacement of the disk protrusion.
Another treatment is exercise. If that does not work, surgical considerations might be explored. I should emphasize that surgery is always the last result, with the exceptions being infection or cancer. For the most part, it is safe. Some patients have the bleeding without pain.