The benefits go beyond feelings of relaxation and wellness that people may recognize after a massage. The American College of Physicians and the American Pain Society now include massage as one of their recommendations for treating low back pain, according to guidelines published in 2007.New research is also starting to reveal just what happens in the body after a massage. While there have long been theories about how massage works—from releasing toxins to improving circulation—those have been fairly nebulous, with little hard evidence. Now, one study, for example, found that a single, 45-minute massage led to a small reduction in the level of cortisol, a stress hormone, in the blood, a decrease in cytokine proteins related to inflammation and allergic reactions, and a boost in white blood cells that fight infection.