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The Somatic Connection  |   May 2016
Spinal Mobilization Has Peripheral Vasodilation Effects
Author Notes
  • Western University of Health Sciences College of Osteopathic Medicine of the Pacific, Pomona, California 
Article Information
The Somatic Connection   |   May 2016
Spinal Mobilization Has Peripheral Vasodilation Effects
The Journal of the American Osteopathic Association, May 2016, Vol. 116, 327. doi:10.7556/jaoa.2016.067
The Journal of the American Osteopathic Association, May 2016, Vol. 116, 327. doi:10.7556/jaoa.2016.067
Zegarra-Parodi R, Pazdernik V, Roustit M, Park PY, Degenhardt BF. Effects of pressure applied during standardized spinal mobilizations on peripheral skin blood flow: a randomized cross-over study. Man Ther. 2016;220-226. doi:10.1016/j.math.2015.08.008. 
Osteopathic physicians who use spinal manipulation claim that it can improve skin blood flow (SBF), but there are few randomized, sham-controlled, cross-over research studies that have evaluated this claim. Researchers at A.T. Still University in Kirksville, Missouri, and at the Grenoble University in France investigated this claim using laser Doppler flowmetry and the inspiratory gap (IG) test to evaluate SBF during and after application of spinal mobilization (SM) and the Novel Pliance-X system pressure monitor to evaluate the influence of pressure on SBF. 
Thirty-two participants (mean [SD] age, 25 [5.4] years) were randomly assigned to 1 of 4 sequences of interventions. Before each session, the participant’s pain pressure threshold (PPT) was determined. The researchers used varied pressures of spinal SM—control (no touch) and SM applied at 5% of PPT (sham), 40% of PPT (low-pressure), or 80% of PPT (high-pressure)—and compared the effects of each intervention on the participant’s SBF. Using a pressure sensor on the thumb, the investigator used the thumb to rhythmically push on the T1 vertebra, over the lamina on the side of the participant’s dominant arm, using a graded translatory pressure toward the base of the participant’s opposite axilla. Measurements were taken at baseline at the end of a 20-minute acclimatization period, during the IG test, 5 minutes after the IG test, during the SM phase (or no manual contact for the control intervention), and 5 minutes after the SM. Thus, 4 interventions were applied on 4 different days, and each 40-minute session comprised 5 phases. 
There were equal and significant bilateral vasodilation measurements during application of unilateral sham SM, low-pressure SM, and high-pressure SM. A significant difference in mean SBF was seen across the second half of each low-pressure SM application and control (P=.007). A significant difference in mean SBF was seen between high-pressure SM and control (P=.008) and between sham SM and control (P=.02). Significant vasodilation persisted only after high-pressure SM (P=.02). 
This study is the first well-controlled investigation to describe bilateral peripheral SBF changes occurring during and 5 minutes after application of standardized SM. The persistence of post-SM vasodilation after only high-pressure SM suggests possible pressure-dependent mechanisms. However, further research is warranted to clarify these findings. Spinal mobilization should also be compared with other manual procedures to determine if this finding is specific to this particular technique.