"Shoes with curved unstable soles are no better than traditional trainers for reducing lower back pain," BBC News reports, after a small but well-designed study found no significant benefit in people wearing "rocker sole" shoes.
The study involved 115 adults with chronic lower back pain who were randomised into two groups: rocker sole trainers or normal trainers. They were asked to wear these trainers for at least two hours a day over the course of a year. They were also asked to exercise once a week for four weeks and wear their trainers to these sessions.
The good news was that in all groups back pain improved to some degree. However, the rocker sole-style footwear was no better (or no worse) than flat sole trainers in reducing disability or pain scores.
For a number of measures the rockers actually fared worse than their flat sole counterparts, including satisfaction with the trainers and a clinically important reduction in self-reported disability.
The study had many strengths, including its randomised design and realistic treatment conditions, which involved prescribing shoes plus exercise rather than just shoes.
However, a general limitation of the study is that it only recruited people with chronic lower back pain, so the effect of the rocker shoes on other musculoskeletal conditions was not tested.
Larger studies assessing pain and disability over a longer period of time would be able to confirm or refute these findings, but initially – and in light of the strengths mentioned above – they appear reliable.
The study was carried out by researchers from UK-based hospitals and universities in collaboration with international partners.
It was funded by Masai GB Ltd, a footwear manufacturer specialising in rocker sole ranges. Because of the largely neutral findings of the study, it is clear the funders had no influence on the study design or reporting.
The study was published in the peer-reviewed medical journal, Spine.
The BBC coverage of the study was balanced and factually accurate.
This was a multicentre, assessor-blind randomised control trial comparing the effectiveness of rocker sole footwear with traditional flat sole footwear for people with chronic lower back pain.
The researchers reported that over the past decade, persistent advertising has claimed that footwear constructed with a rocker sole will reduce lower back pain. Shoes with an unstable curved sole are often marketed as being able to help increase muscle activity, reduce lower back pain and improve posture and balance when walking and standing.
However, as the authors noted, there is no robust evidence to support these claims. The present study aimed to provide robust evidence on whether rocker sole shoes helped lower back pain.
A randomised control trial is the best study design for comparing the effectiveness of two treatments, such as two different types of footwear that could be recommended as part of lower back pain management.
It is not possible for such a trial to be double blind, as participants would know what shoes they were wearing, but the fact that the assessors were blind to treatment allocation (single blind) is a strength.
The study recruited 115 adults with chronic lower back pain (three months duration or longer) who were randomised to wear either rocker sole shoes or flat sole shoes while standing and walking for a minimum of two hours each day.
The researchers excluded people with a diagnosed medical cause for their back pain and those for whom a prescription of rocker shoes and exercise would be inappropriate, for example, people with neurological conditions, a history of falls, or severe cardiovascular disease.
Participants were assessed after six weeks, six months and one year using a disability questionnaire called the Roland Morris Disability Questionnaire (RMDQ).
Importantly, participants' disabilities were assessed by an assessor who did not know which shoes the participants had been wearing, making the study single blinded.
Measures of pain, health-related quality of life and the time participants had spent in their shoes were also recorded at each of the time points.
As well as wearing the shoes, all participants attended an exercise and education programme once a week for four weeks and wore their assigned shoes during these sessions.
Analysis was by an intention-to-treat method, meaning all participants initially randomised were analysed in the final results, including those who dropped out of the study later on. This is the best way of analysing results from studies such as this, as it captures all the participants.
The main results were as follows:
The researchers drew four main conclusions from their research findings:
This study indicates that rocker sole-style footwear is no more beneficial than flat sole trainers in reducing disability and pain outcomes in adult chronic lower back pain sufferers. For a number of measures, such as satisfaction with the trainers and a clinically important reduction in self-reported disability, the rockers fared worse than their flat sole counterparts.
The study had many strengths, including its randomised and single blind design, realistic intervention conditions (prescribing shoes plus exercise rather than just shoes) and having an appropriate number of people in their study. Taken together, the study appears reliable and its results robust.
A general limitation is that the study only recruited chronic back pain sufferers, so the effect of the shoes in people with shorter term lower back pain (less than three months), or other muscular conditions where the shoes might be considered beneficial, was not tested. However, chronic back pain sufferers are the group most likely to try the shoes, so this was a realistic approach to take.
Larger studies assessing pain and disability over a longer period of time would be able to confirm or refute these findings.