Although the paper by Kohlenberg (2021) raises some cogent questions about the necessity for accurately assessing resonance frequency (RF), the argument is an oversimplification and, we believe, underestimates its importance. Several issues are involved: (a) does breathing at exact RF produce greater amplitudes of heart rate variability (HRV) than simply breathing at six breaths per minute, (b) does breathing at exact RF have any clinical advantage, and (c) can RF be accurately determined using currently accepted procedures?

The answer to this question is yes. Transfer functions we have published previously (Vaschillo et al., 2002; Vaschillo et al., 2004) show a gradual increase in HRV amplitude as breathing approaches RF, with one frequency producing the highest HRV amplitude. The same is true for baroreflex gain. This is the RF.

There are some statistical data that bear on this, but not...

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