Lower back pain is a common health problem, and is usually treated with self-care and over-the-counter medication.
For some people it may last for three months or more, and at this point it is considered "chronic".
Back pain is sometimes associated with a disease or condition, but the vast majority of lower back pain cases have an unknown cause, and as a result are described as non-specific.
Current guidelines state that exercise therapy may be beneficial, and in particular yoga is sometimes used as a treatment.
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Yoga has gained global popularity as a form of mind-body exercise, with general life-style benefits, and recent studies have investigated the potential of yoga to relieve the symptoms of lower back related problems.
The new review summarises the results of 12 randomised trials from 1,080 men and women with an average age between 34 and 48 years old.
The trials were conducted in India, the UK and the US. All participants had chronic non-specific lower back pain.
Seven studies compared yoga with no exercise, three studies compared yoga with back-focused exercise, or added yoga for a back-focused exercise programme.
Two studies compared yoga with two other forms of control group: no exercise or a self-care book.
All yoga interventions used were specifically designed for treatment of lower back pain, and were provided by experienced and qualified teachers.
Researchers found that compared to no exercise, practising yoga might improve back-related function and may also reduce symptoms of lower back pain by a small amount in the first six to twelve months, although the effect was consistently less than that judged to be clinically important.
However, yoga may cause an increase in back pain in some people. About five per cent more yoga participants experienced increased back pain, although this may be similar to the risk of having side effects from other back-focused exercise.
"At the moment we only have low to moderate quality evidence for the effects of yoga before six months as a type of exercise for helping people with chronic lower back pain," said Wieland.
The research was published in the journal Cochrane Library.