Effects of Temporary Respiration Exercise with Individual Harmonic Frequency on Blood Pressure and Autonomic Balance

Figure 1. Overview of the closed system between heart rate variability, blood pressure, and respiration.

Figure 2. The experimental process.

Figure 3. Overview of the signal processing to achieve resonant frequency. Top gray boxes represent the time domain index of the ECG data and the bottom gray boxes represent natural log values of LF and HF characterized for autonomic balance with nine zones.

Figure 4. Example of harmonic frequency in participant 1 based on the highest amplitude value among the respiration conditions.

Figure 5. The zone of autonomic balance using HRV spectrum analysis.

Figure 6. Comparison of results of systolic blood pressure between free respiration and resonance frequency. The resonance frequency was within the optimal range after respiration task, unrelated to the state before the task. On the other hand, the free respiration condition was within the (pre)hypertension state; thus, it was not in the optimal range.

Figure 7. Comparison of results of diastolic blood pressure between free respiration and resonance frequency. The resonance frequency, to diastolic blood pressure, was within the optimal range after respiration task and unrelated to the state before task. However, the free respiration condition was not within the optimal range.

Figure 8. Example of change in autonomic balance in participant 3 causing respiration conditions. The resonance frequency was respiration condition 10, and it was only located in the reference zone. The other respiration condition including free respiration condition was not located in the reference zone.

Figure 9. Example of change in autonomic balance in participant 8 causing respiration conditions. The resonance frequency was respiration condition 8, and the other respiration conditions (7.5 and 8.5) with resonance frequency were located in the reference zone.

Figure 10. Comparison of results of autonomic balance between free respiration and resonance frequency. The resonance frequency was within the reference zone after respiration task. However, the free respiration condition was not within the reference zone, and almost all participants were located in zones 4 and 5, such as unstable state of autonomic balance (high sympathetic, normal, and low parasympathetic). The time domain LF and HF indices can be quantified during 2 min to 24 h monitoring periods. We obtained the minimum range of ECG data to investigate the short-term harmonic respiration effects; therefore, how changes in autonomic balance evolve over time is not provided here.

Figure 11. Comparison results of time domain indices of SDNN (A), rMSSD (B), and pNN50 (C) for the free respiration and resonance frequency condition with paired t-tests (*** p < 0.001, ** p < 0.007 adjusted by Bonferroni correction).

Figure 12. Results of permutation tests for free and harmonic respiration. The underline in the upper right corner of each figure represents empirical p-values.