Inversion tables are devices which designed to allow spinal traction. Traction is a type of low back treatment which involves stretching the spine vertically i.e. pulling the vertebrae in opposite directions.
The stretch can be applied either:
The principle behind it is that the distraction force of the traction causes a reduction in muscle spasm and pain.
There are mixed reviews but the most up to date research (1) examined 25 studies of treatment using traction with 2206 patients with lower back pain. The results from that study are not too promising with the evidence suggesting that traction as a treatment for lower back pain was not more effective than placebo, sham treatment or any other treatments.
There are some problems with the quality of the research for traction, many manufacturers of traction devices quote ancient studies looking at the biomechanical effects of traction, few well designed research trials have compared traction devices such as inversion tables to a control group who had no treatment at all. This makes it difficult to say for sure whether it is helpful or not.
This major systematic review was updated in 2007 (2) and checked again in 2010 and the authors conclusions remain similar:
They say:'The results of the available studies were quite consistent ....continuous or intermittent traction as a single treatment for LBP is not likely effective for this group.'
The authors conclude:
'traction as a single treatment for LBP is probably not effective.'
1. Clarke, J. M., van Tulder, M. P., Blomberg, S. M., de Vet, H. P., van der Heijden, G. P., & Bronfort, G. D. 2006, "Traction for Low Back Pain With or Without Sciatica: An Updated Systematic Review Within the Framework of the Cochrane Collaboration.", Spine, vol. 31, no. 14, pp. 1591-1599.
2. Clarke, J.A. et al. Traction for low-back pain with or without sciatica. Cochrane Database of Systematic Reviews (2007).