Physiological effects of spinal manipulation: a review of proposed theories.

High velocity low amplitude thrust (HVLAT) or manipulation is commonly used for the treatment of back pain. This critical review of the proposed mechanisms of action was based on a database search using the keywords: spinal manipulation, low back pain, osteopathy, physiotherapy and chiropractic. Three proposed mechanisms were highlighted – biomechanical, muscular reflexogenic, and neurophysiological. There is evidence of a mechanical gapping of the facet joints during manipulation, although the clinical significance of this is not clear. There is also evidence to support the theory that HVLAT techniques evoke spinal stretch reflexes resulting in a brief muscle contraction possibly followed by a period of reduced muscle activity. The papers also provide support for the anti-nociceptive treatment effects of HVLAT and this would have obvious benefit to the patient. In conclusion, there is support in the literature for each of the mechanisms, but it is clear that more research is needed to further our understanding of the mechanisms underlying spinal manipulation. [ABSTRACT FROM AUTHOR]