Background:
Analysis of rhythmic patterns embedded within beat-to-beat variations in heart rate (heart rate variability) is a tool used to assess the balance of cardiac autonomic nervous activity and may be predictive for prognosis of some medical conditions, such as myocardial infarction. It has also been used to evaluate the impact of manipulative therapeutics and body position on autonomic regulation of the cardiovascular system. However, few have compared cardiac autonomic activity in supine and prone positions, postures commonly assumed by patients in manual therapy. We intend to redress this deficiency.

Methods:
Heart rate, heart rate variability, and beat-to-beat blood pressure were measured in young, healthy non-smokers, during prone, supine, and sitting postures and with breathing paced at 0.25 Hz. Data were recorded for 5 minutes in each posture: Day 1 – prone and supine; Day 2 – prone and sitting. Paired t-tests or Wilcoxon signed-rank tests were used to evaluate posture-related differences in blood pressure, heart rate, and heart rate variability.

Results:
Prone versus supine: blood pressure and heart rate were significantly higher in the prone posture (p < 0.001). Prone versus sitting: blood pressure was higher and heart rate was lower in the prone posture (p < 0.05) and significant differences were found in some components of heart rate variability.

Conclusion:
Cardiac autonomic activity was not measurably different in prone and supine postures, but heart rate and blood pressure were. Although heart rate variability parameters indicated sympathetic dominance during sitting (supporting work of others), blood pressure was higher in the prone posture.
These differences should be considered when autonomic regulation of cardiovascular function is studied in different postures.

Grant Value: $60,000
Chief Investigator: Dr Barbara Polus – RMIT
Status: Complete

Publications:

Posters:

Presentations:

  • Proceedings of The 5th ISAN (International Society for Autonomic Neuroscience) congress, October 2007. Kyoto, Japan
    Watanabe N, Potocnik S, Polus BI. The contribution of neck sensory inputs to cardiovascular regulation during moderate head-up tilt in humans.
  • Proceedings of The 7th IBRO World Congress of Neuroscience, July 2007. Melbourne, Australia
    Watanabe N, Reece J and Polus BI The effects of mechanical impulse to the neck on cardiac autonomic and cardiovascular functions in young healthy adults; is it an artefact or a genuine response?
  • Proceedings of The 7th IBRO World Congress of Neuroscience, July 2007. Melbourne, Australia

    Watanabe N, Potocnik S and Polus BI. The role of proprioceptive inputs from the dorsal neck to cardiovascular regulation during orthostasis in humans.
  • The 3rd Research Conference School of Health Sciences, RMIT University, July 2007. Melbourne, Australia
    Watanabe N, Potocnik S and Polus BI The role of proprioceptive inputs from the dorsal neck to cardiovascular regulation during orthostasis in humans.
  • Proceedings of The World Federation of Chiropractic 8th Biennial Congress June 2005. Sydney, Australia p.254
    Watanabe N and Polus BI (2005) The effects of body posture on autonomic regulation of cardiovascular function.

Awards

  • First Prize – The 3rd Research Conference School of Health Sciences, RMIT University, July 2007. Melbourne, Australia
    Watanabe N, Potocnik S and Polus BI The role of proprioceptive inputs from the dorsal neck to cardiovascular regulation during orthostasis in humans.