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).

Evaluation:
– 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.