Spinal manipulation does not affect pressure pain thresholds in the absence of neuromodulators: a randomized...

Measurement of pressure pain threshold (PPT) is a way to determine one of the many potential treatment effects of spinal manipulative therapy.

To determine how multiple spinal manipulations administered in a single-session affected PPTs at local and distal sites in asymptomatic individuals.

Participants were randomly assigned into one of three groups: Group one (n = 18) received a lumbar manipulation followed by a cervical manipulation. Group two (n = 17) received a cervical manipulation followed by a lumbar manipulation. The control group (n = 19) received two bouts of five minutes of rest. At baseline and after each intervention or rest period, each participant's PPTs were obtained using a handheld algometer. The PPTs were tested bilaterally over the lateral epicondyles of the humerus and over the mid-bellies of the upper trapezius, lumbar paraspinal, and the tibialis anterior muscles. This study was registered with ClinicalTrials.gov, and its Identifier is NCT02828501.

Repeated-measures ANOVAs and Kruskal-Wallis tests showed no significant within- or between-group differences in PPT. Within-group effect sizes in the changes of PPT ranged from -.48 at the left paraspinal muscles to .24 at the left lateral humeral epicondyle. Statistical power to detect significant differences at α of 0.05 was calculated to be 0.94.

This study suggests that in young adults who do not have current or recent symptoms of spinal pain, multiple within-session treatments of cervical and lumbar spinal manipulation fail to influence PPTs. Changes in PPT that are observed in symptomatic individuals are likely to be primarily influenced by pain-related neuromodulators rather than by an isolated, mechanical effect of spinal manipulation.