Metcalfe S, et al. Effect of High-Velocity Low-Amplitude Manipulation on Cervical Spine Muscle Strength: A Randomized Clinical Trial. Journal of Manual & Manipulative Therapy 2006; 14(3):152-158.
ABSTRACT: Clinical observation suggests that side-to-side differences in anterolateral neck flexor strength may be resolved by appropriate high-velocity low-amplitude manipulation of a dysfunctional upper cervical segment. We examined 67 patients with mechanical neck pain or cervicogenic headaches to evaluate the change in anterolateral neck flexor strength. The subjects were randomly assigned to two groups. The control group received spinal manipulation to dysfunctional segments in both the upper and lower cervical spine. Following manipulation of the upper of the upper and lower cervical spine, the predicted weak side of the treatment group showed greater improvement in strength compared to the predicted strong side. Also, following manipulation, there was a greater increase in strength of the predicted weak side of the treatment group compared to the predicted weak side of the control group. We also studied the interrater reliability of positional palpation of atlas and determined the relationship between the relative position of the atlas and anterolateral neck flexor strength.
COMMENTS: In this study, it was found that high velocity, low-amplitude manipulation of both the upper and lower cervical spine benefited those with mechanical neck pain – palpable fixation or hypomobility – to a greater degree than the control group which received lower cervical spine manipulation only. A photo shows an example of the manipulation used on atlas showed a large degree of lateral flexion but not much rotation. The contact appears to be a very broad contact along the length of the index finger. They measure, bilaterally, the strength of the anterolateral cervical muscles pre- and post-. Another finding was muscle weakness on the side of palpable rotation of the atlas (I assume that it means on the side of palpable laterality because the atlas rotates as a unit; segmental dysfunction and contact was determined solely by palpation). They found that following manipulation of the upper and lower cervical spine. the side that was weaker regained strength. The stronger side became stronger but not to the degree of the weaker side. There was bilateral strengthening of the cervical spine muscles. They wrote: “Manipulation appears to be of benefit at a neurological level and results in a change of the afferent excitation levels of the sensory impulses originating from a segmental segment.”
The concluding statement resonates with Gonstead chiropractors: “The study also provides guarded support for the need for segment and direction-specific manipulative interventions in patients with mechanical neck pain.”