Studies have shown that through massage during the treatment of injuries, patients have experienced a statistically significant improvement in function, reported less intense pain, and experienced a decrease in the quality of pain compared to those who received other interventions or none at all
see reference study here https://www.ncbi.nlm.nih.gov/pubmed/10906914
Studies have also shown that massage in the treatment of chronic lower back pain is very effective
see reference study here https://www.ncbi.nlm.nih.gov/pubmed/12221356
It is important to note with both these studies though that the massage was supported by a good exercise programme as well as patient education on the causes of lower back pain.