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John Hart


Heart Rate Varaiability, Spinal Manipulation


Introduction: Timing of a health care intervention is often a key factor in the success of a clinical procedure. This case study of a chiropractic practice analyzes heart rate variability (HRV) as a method of determining optimal timing for spinal adjustment.

Methods: Thirty-eight patients’ HRV findings were analyzed retrospectively to determine if an optimal HRV value was associated with greater (improved) HRV responses following their spinal adjustment. The HRV measure considered in this study was the time domain metric of root mean square of the successive differences between heart beats (rMSSD). The terms rMSSD and HRV are used interchangeably in this paper. Post-pre HRV change was the dependent variable and compared between low versus high pre-adjustment HRV. A 2- ailed p-value of 0.05 was considered statistically significant.

Results: Patients whose pre-adjustment HRV values were 25.5 milliseconds (ms) or lower tended to show better (larger) HRV changes compared to patients having HRV values of 28.0 ms or higher (p = 0.0026, effect size = 2.0).

Conclusions: In this case study, patients who had rMSSD values of 28.0 ms or higher may not have needed a spinal adjustment according to HRV, evidenced by their worsened post-adjustment HRV values. Further study in other chiropractic practices is a reasonable next step.


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