The purpose of this study is to determine if specific Chiropractic adjustments cause any significant changes in blood pressure via stimulation of the sympathetic nervous system.

Sixty “normal healthy” subjects aged between I8-35 years will be chosen to participate in the study. These subjects will be placed randomly into two groups (i.e. an active and a control) based on the clinical findings using standard chiropractic palpatory methods (all clinical procedures will be carried out identically on each group).

The first group, the experimental group will be fanned on the basis that they have one or more subluxations between the first and fifth vertebrae of the thoracic spine (Tl-TS). The thoracic treatment will be delivered by a skilled chiropractic practitioner using extension wing lift adjustments (outlined by O’Neil and Esposito 1991).

The second group, the control group will also have one or more subluxations between Tl-TS but no treatment or adjustive procedure will be performed on them. Blood pressure measurements will be taken and recorded with a photoplethysmograph immediately before and after for each group. Blood pressure measurements will be taken twice a week for three (3) weeks, to determine long term effects. Both systolic and diastolic blood pressures will be recorded.

Grant Value: $1,200
Chief Investigator: Dr Henry Pollard – Macquaire University
Status: Complete

Research Update:

  • This project investigated the response of blood volume pulse in asymptomatic freely consenting volunteers who had given written consent.  There were two groups of subjects that were randomly allocated.  The first experimental group received a mild thoracic manipulative procedure in the sitting position.  The second group received a sham thrust in the same sitting position at the same level on the spine.  The sitting position was chosen to minimise the change in intra-thoracic and or intra-abdominal pressure that would occur with a prone adjustment.  Reflex changes of heart rate and blood pressure could be mediated via baroreceptor activity secondary to a change in these cavity pressures.  
  • The use of manipulations in the prone position would have severely flawed previous attempts at quantifying any blood pressure changes associated with manipulation, by the pressure effects exerted with the manipulation. We felt that the sitting position would minimise these effects allowing the true nature of the effects of the manipulative thrust to be maximised.  The position of the measurement device relative to the heart was held constant between assessments so as not to change the return pressure on the heart as well as the peripheral resistance with orthostasis.
  • The results of this project demonstrated no significant change in blood volume pulse following a manipulative thrust to the T3-5 segments between the sham manipulation group and the experimental manipulation group.