This project investigates the impact of the subluxation on joint position sense and movement. Chiropractors and their patients often report improvements in balance and coordination after having chiropractic care. In physiological terms, this may be defined as a decrease in the ability to accurately perceive where the limb is in space and how it is moving. This project plans to examine the plausibility that such improvements may be attributable to removal of the chiropractic subluxation. DD Palmer, the founder of chiropractic, defined the chiropractic subluxation as “too little or
too much nerve energy”. We have translated this definition into physiological terms – subluxation is a mechanical derangement with a resultant disruption of appropriate / accurate sensory signals that are transmitted into the central nervous system. One consequence of this disruption that may be experienced by patients is clumsiness – a decrease in the ability to accurately perceive where the limb is in space and how it is moving.

We have developed a physiological model of subluxation that exploits the property of muscle thixotropy. This phenomenon is usually applied to fluids that become stiff and viscous at rest but more fluid when stirred. Muscle also exhibits thixotropic behaviour. When the muscle is at rest, the muscle becomes stiff; when the muscle moves, stiffness is reduced. By exploiting muscle thixotropy, we are able to alter neck muscle stiffness and therefore the output from the muscle spindles (the length detectors) of the neck in a predictable way, either increasing or decreasing the quantity of the sensory signals. By changing the quantity of sensory signals from the neck we can measure the effect of ‘too much or too little nerve energy’ on the accuracy of a person’s perception of where body segments are in space and in relation to each other. This project may provide evidence to support the proposal that chiropractic subluxation contributes to clumsiness.

Grant Value: $36,192
Chief Investigator:
 Dr Barbara Polus – RMIT
Status: Complete



  • COCA Researchers’ Day, Sydney , Australia
    Harman, S., Wong, M,. Polus BI. “The role of neck muscles in understanding where our body lies in space” peoples’ choice poster award 
  • Chiropractor’s Association of Australia Annual Conference  ,Cairns, QLD, Australia
    Harman, S., Zheng, Z., Azari, MF. and Polus BI 2016 “Is the pain in my neck making me clumsy? A systematic review of clinical and neurophysiological studies in humans.” Poster presentation finalist 
  • Engineering and Health HDR Student Conference ‘From Inception to Excellence’ 2012, RMIT University, VIC, Australia
    Harman, S., Azari, MF. And Polus BI. 2012 “Role of neck proprioceptive afferents in producing symptoms of clumsiness in patients with neck pain and injury“ poster presentation
  • Australian Neuroscience Society Sensorimotor Satellite Meeting  February 2014, Adelaide, Australia
    Harman, S., Zheng, Z., Azari, MF. and Polus BI  2014 ‘The Association Between Neck Pain and Injury and Errors In Limb Position Sense and Movement: Systematic Literature Review’