This study from researchers at the University of Salzburg in Austria that looked at spinal alignment and muscle activity of selected muscles in the back while standing in typical shoes and MBT shoes.
The main findings were:
Results showed that wearing unstable MBT shoes increased flexion at the mid-thoracic level (0.8°; P = 0.001) and led to greater mean velocities of angular displacement at the thoracolumbar (11.2%; P = 0.003) and at the lumbopelvic (10.8%; P = 0.02) regions, accompanied by more lumbar erector spinae activity (18.2%; P = 0.003).
– this was done during standing and not walking
– it does confirm that there are changes in the low back, spine and muscle activity with the use of unstable or toning shoes
While adding to the body of knowledge on the biomechanical effects of toning shoes, more work is needed to determine the actual ‘clinical’ effects of those changes.
Those with diabetes mellitus have an increased risk for falls. This is mostly due to the development of peripheral neuropathy which reduces the sensory input from the plantar surface of the foot. This neuropathy also puts them at increased risk for complication such a plantar ulcers, often referred to as the diabetic foot. A number of different strategies are often used to reduce the pressures under the ball of the foot to reduce the risk of these complications. One of these methods is a rocker bottom shoe. This has been shown to reduce plantar pressures, but there is a risk it may increase the risk for falls due to the instability the rocker may create.
A study in Gait and Posture from researchers at East Carolina University used 20 healthy controls to investigate what rocker sole shoes did to parameters associated with the center of mass and center of pressure which are measure of postural stability. They concluded:
In young healthy adults, shoes with rocker bottom soles had a destabilizing effect to perturbed stance, thereby increasing the potential for imbalance. These results raise concerns that footwear with rocker bottom sole modifications to accommodate an insensate foot may increase the risk of falls.
– the subjects were healthy adults and not people with diabetic neuropathy.
– its does point to a theoretical increase in instability in those who do have diabetic neuropathy.
– rocker sole shoes probably should be used with caution in those with diabetic foot complications, especially if they have other risk factors present for falls.
A study published in Clinical Biomechanics (online Sept 2012) looked at pain levels in people aged 40-65 with plantar fasciitis. Using a visual analogue pain scale, they compared the use of foot orthotics to toning shoes to foot orthotics and toning shoes.
The pain scores on the VAS for the 3 conditions were:
Rocker shoes and foot orthotics: 9.7mm
Rocker shoes: 30.9
Foot Orthoses 29.5
So the rockers shoes combined with foot orthoses produced the best results and the authors concluded:
The findings indicate that a combined prescription of rocker sole shoes and custom-made foot orthoses had greater immediate therapeutic effects compared to when each treatment had been individually prescribed.
– this is not a very commonly used intervention for treating plantar fasciitis
– this was an acute intervention and the participants were not followed over time
– the VAS is not the most validated measure for pain levels in plantar fascitis
For more on plantar fasciitis, see this post.and this essay. Run Junkie has one of the sensible approaches to it.
Intermittent claudication is the name given to the symptoms that occur, usually in the calf muscle, in those with poor circulation. It occurs after walking a set distance because the oxygen supply to the muscle cannot meet the muscles’ needs. This pilot study from researchers at the University of Salford in the United Kingdom and published in the Journal of Vascular Nursing looked at the use of a rocker sole shoe which mimics the action of toning shoes in a group of people with intermittent claudication. The participants were given two therapeutic shoes that were identical, except that one had a specific three-curve rocker sole. Participants then did walking trials to determine the distance until the claudication pain occurred and the intensity of the pain. They found that while wearing the rocker sole shoes, the distance until claudication increased and the intensity of the claudication pain was less.
This study is promising. It was only in eight people and was only done in one session. It is not known if the benefits demonstrated would be apparent after a longer period if adaptation to the rocker soles shoes was allowed to occur.
Link to study