Osteopathic manipulative treatment and its relationship to the activity of the autonomic nervous system demonstrated by heart rate variability.
Indirect and non-invasive methods that provide markers of ANS balance have been developed and improved over the past decades. One of the most widely used methods is heart rate variability (HRV). HRV is used to study autonomic balance and it is generally accepted that the high frequency (HF) component can be used as a marker for vagal heart rate modulation. The low frequency / high frequency (LF / HF) ratio also accurately reflects the autonomous balance.
Method
28 subjects were included in the study. They were between 19 and 50 years old, were in good health, and had a normal ECG as well as normal blood pressure.
There were three experimental conditions : control without intervention; OMT treatment involving cervical myofascial release, and sham treatment involving hand placement in the cervical region (sham).
The protocol lasted 30 minutes. Changes in body position (horizontal versus head-up tilt of 50 degrees, which corresponds to tilt) were incorporated into the study to facilitate interpretation of autonomic tone measurements. ECG data was recorded continuously throughout the experiment.
The analysis of autonomic tone has been standardized. It was performed in the last 5 minutes of horizontal period 1, the last 5 minutes of incline, and during the first 5 minutes of heart rate recovery in horizontal period 2. Treatment, either OMT or sham, was performed. administered for 2 minutes and started 30 seconds after the start of the incline. After the treatment phase, the subjects remained in an upright position for 8 min.
They participated in each of the three separate sessions during which only one of the experimental conditions (control, OMT, sham) was administered.
In the first session, each subject was randomly assigned to one of two treatment conditions, OMT or sham. Subjects then received the other treatment condition during the second session. The control condition was administered as the third condition. The subjects did not know what treatment they were receiving at the time.
All the sessions were administered under the same conditions (time, place, etc.).
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Results
17 (9 males and 8 females) of the 28 subjects completed the study. The exclusions correspond to an absence of modification of the ECG at the time of the tilt, a schedule conflict or a move.
Low frequencies (LF) increased significantly under control and simulation conditions when subjects were moved from horizontal tilt to head-up tilt, F = 47.35, p <0.001. The magnitude of the change was similar under the control and simulation conditions.
However, when the OMT treatment was applied in the head-up position, the increase in LF was significantly less compared to the increases in LF that occurred under the control and simulation conditions (p <0.001). LF returned to baseline under all three experimental conditions when subjects were returned to a horizontal position.
In the head-up tilt position, the high frequencies (HF) under control and simulation conditions have significantly decreased, F = 43.005, p <0.001. The change in HF was not as large under the OMT treatment condition (p <0.001).
Head-up tilt significantly increased the LF / HF ratio in all three conditions, F = 30.49, p <0.001, reflecting an increase in sympathetic tone. The increase in the LF / HF ratio was due to an increase in LF and a decrease in HF power. Cervical myofascial release resulted in a lower LF / HF ratio in the head-up tilt phase by decreasing LF and increasing HF power relative to control and sham.
Conclusion
This study quantitatively shows the effect on the ortho / parasympathetic balance of a cervical myofascial technique via its parasympathetic action.
The authors suggest carrying out other studies using other techniques in order to see their impact on the autonomic nervous system, as well as carrying out similar studies in the subject presenting a pathology.
References
Henley CE, Ivins D, Mills M, Wen FK, Benjamin BA. Osteopathic manipulative treatment and its relationship to autonomic nervous system activity as demonstrated by heart rate variability: a repeated measures study. Osteopath Med Prim Care. 2008 Jun 5; 2: 7.
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