Curved soles 'no better' than trainers for back pain
But previously published research has shown that the shoes can have a positive impact on posture, back and joint pain.
Medical professionals are known to regularly recommend the shoes.
The study also said normal trainers may be more beneficial for back pain brought on by standing or walking.
Shoes with an unstable curved sole are often sold as being able to help increase muscle activity, reduce lower back pain and improve posture and balance.
Physiotherapist Dr Sian MacRae, who led the research during her PhD at King's College London, said patients were always asking her if 'rocker sole' footwear worked, so she decided to find out if they could improve back pain and disability.
In the study, in the journal Spine, 115 people with chronic lower back pain were asked to wear rocker sole shoes or normal trainers for at least two hours a day while standing and walking.
They also attended an exercise and education programme once a week for four weeks and wore their shoes during these sessions.
After six weeks, six months and then one year, the participants were assessed using a disability questionnaire.
At the end of the study, researchers calculated that people in the trainer-wearing group experienced a larger reduction in disability than those in the rocker sole group.
After six months, 53% of the trainer group showed a small improvement in their back mobility compared to 31% of the rocker sole group.
For the 59 people who said their back pain was aggravated by standing and walking at the start of the study, those in the trainers group experienced a greater reduction in disability after one year than those in the rocker sole group.
Dr MacRae said: "On the basis of the findings of this randomised clinical trial, clinicians should be confident in advising patients with chronic lower back pain that wearing either rocker sole shoes or trainers may offer similar outcomes in disability and pain.
"However, if a patient reports lower back pain when standing or walking, it may be more beneficial to wear trainers than rocker sole shoes."
Noel May, a spokesman for Masai Barefoot Techonology (MBT), which makes unstable footwear, said many other studies had been published showing that shoes with curved soles could reduce pressure on the joints and have a positive impact on posture.
"We are unique in having a significant number of scientifically published studies combined with vast empirical evidence from user stories over many years.
"I have great respect for studies based on questionnaires such as this one but we know that all sorts of things impact people's response to wellness questionnaires, including the attitude of the person conducting the study, the economy and even the weather.
"We have people every week who have written to us stating how beneficial the shoes have been for them over the years including many being helped with lower back pain."