The journal Spine recently published the results of a study that concluded:
In patients with musculoskeletal pain, spinal manipulation (SMT) on the upper thoracic spine led to an immediate improvement in the resting cardiac autonomic control without an effect on the blood pressure responsiveness to a sympathoexcitatory stimulus. Myofascial manipulation or placebo did not change cardiovascular autonomic control.[i]
The article did not mention in detail what SMT technique was performed and how the spinal segmental level to apply it to was ascertained. After contacting the author of this study, he explained that it was a supine thrust (i.e. “anteriority” style) at the upper thoracic spine (between T1 and T4) without a specific level. A potential segment dysfunction was not assessed before the intervention.
Basically, this protocol was one of, “crack the back” and see what happens. I view this as a true example of “spinal manipulation”, as contrasted with a “chiropractic adjustment”.
These results are interesting when combined to a 2018 RCT study in Spine, which used an activator device and a full spine manipulation. It showed, “a single pre-exercise SMT session induced an acute shift toward parasympathetic dominance and slightly impaired performance in recreational healthy athletes.”[ii]
These 2 studies demonstrate that the application of spinal manipulation has autonomic effects that appear to down-regulate sympathetic activity, and up-regulate parasympathetic activity.
[i] Rodrigues, Pedro Teixeira Vidinha MSca; Corrêa, Leticia Amaral MSca; Reis, Felipe José Jandre PhDb; Meziat-Filho, Ney Armando PhDa; Silva, Bruno Moreira PhDc; Nogueira, Leandro Alberto Calazans PhDa,b One Session of Spinal Manipulation Improves the Cardiac Autonomic Control in Patients with Musculoskeletal Pain, SPINE: January 25, 2021 – Volume Publish Ahead of Print – Issue – doi: 10.1097/BRS.0000000000003962
[ii] Valenzuela, Pedro L. MSc∗,†; Pancorbo, Sara MChiro‡; Lucia, Alejandro MD, PhD§; Germain, Francisco MD, PhD∗ Spinal Manipulative Therapy Effects in Autonomic Regulation and Exercise Performance in Recreational Healthy Athletes, SPINE: May 1, 2019 – Volume 44 – Issue 9 – p 609-614
doi: 10.1097/BRS.0000000000002908
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