A Somatovisceral Reflex of Lowered Blood Pressure and Pulse Rate

Steven David Roffers, J. Michael Menke, David Houston Morris


OBJECTIVE: A randomized controlled trial (RCT) was designed to test effects of specific thoracic (T1 to T5) manipulations using an Activator instrument for changes in diastolic and systolic blood pressure, blood pressure classification, and pulse rates in 290 normotensive and hypertensive people in El Salvador.

METHODS: Informed consent was obtained from 290 subjects meeting the inclusion criteria.

They were randomly assigned to one of three groups: Control (i.e., no treatment, N=95); Placebo treatment (N=96); or Active treatment (N=99). Subjects’ blood pressure and pulse rates were measured after relaxing for 15 minutes, then before intervention, and again just after treatment.

RESULTS: Systolic and diastolic BP, pulse rate, and BP classification decreased significantly only in the active treatment group. No significant changes occurred in the placebo treatment and control groups. Activator treatment’s effect size in changing hypertension classification as compared to no treatment was a medium d = 0.37, and 0.45 when compared to placebo.

CONCLUSION: Specific thoracic spinal manipulations affected three measures: blood pressure, pulse rate, and changes in hypertension classification only in the active treatment group.  Findings may represent in part a rebound effect from treatment anxiety, but this alone did not account for the observations. Activator instrument’s utility for sham settings was supported for future efficacy studies. The decrease was robust across several analyses, but the duration of the effect requires longer-term follow up.


Spinal manipulative therapy; Somatovisceral reflex; Activator instrument; Thoracic; Systolic blood pressure; Diastolic blood pressure; Pulse Rate

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