A recent study was designed to assess the effect of orthotics upon both manual muscle testing and the duration of effects produced by the chiropractic manipulation of the spine. It accomplished this by challenging the manipulation with daily activities (including walking and standing) and determining whether the use of custom foot orthotics prolongs the effects of manipulation which are presumably diminished over time by these activities. Using a means of testing several muscles bilaterally (gluteus maximus, popliteus, lower trapezius, middle deltoid, and neck extensors) in what is known as an applied kinesiology technique, it followed the natural history of indicator muscles of back pain upon their testing with or without orthotics and correlated these results with those of pain and disability, determining whether manual muscle testing results might be predictive indicators of pain and disability as well.
The design of the investigation was a randomized controlled trial, in which one group received a custom fitted orthotic sole and the other a contoured sham device. The effects of manipulation were assessed by two primary outcome measures: (1) the Quadruple Visual Analog Scale (VAS) and (2) the Roland-Morris Disability Scale (RMS), and two secondary measures: (1) the determination of the number and location of vertebral fixations [FIX] as determined by palpation and challenge, (2) the determination of the number of weak muscles [WkMus] by a qualified AK clinician, the muscles having been considered relevant by the tenets of applied kinesiology (AK).