Resonance Frequency Assessment: The Challenge of Standardizing Heart Rate Variability Biofeedback Research

Abstract

The resonance frequency (RF) is the rate at which a system, like the cardiovascular system, can be activated or stimulated for maximal variability. Precise RF measurement is needed to standardize training protocols to help researchers determine the importance of RF breathing in achieving clinical and optimal performance outcomes. Lehrer and colleagues have developed and standardized a psychometrically reliable RF measurement protocol that can facilitate training and replication. This article provides a detailed description of their protocol and explains the nuanced decision-making process involved in identifying the RF. The validity and reproducibility of results using this protocol depend on quality control in (a) confirming that individuals successfully follow a breathing pacer, and (b) manually removing artifacts from data records. While this protocol requires an electrocardiogram or photoplethysmograph sensor and a respirometer, professionals should consider the addition of autonomic, musculoskeletal, and respiratory measures to better understand the patterns of physiological activity produced by different breathing rates.

A Practical Guide to Resonance Frequency Assessment for Heart Rate Variability Biofeedback

“…If your clients entered training to lower blood pressure, consider the rate that produces the greatest decreases. In response to the previous example, breathing at 5.0 bpm reduced blood pressure by 9/12 mmHg compared with 5.5 bpm (Shaffer, 2020). When you collaborate with your clients to break ties, you can strengthen your relationship and increase the likelihood that they will practice resonance frequency breathing outside of the clinic.…”

“…Skin conductance level (SCL) is a tonic measure of eccrine sweat gland activity. Furthermore, an EMG , which monitors skeletal muscle action potentials, can likewise indicate dysfunctional breathing if frontales or breathing accessory muscles exceed normal resting values of ≤3 microvolts (μV; Shaffer, 2020 ). For example, elevated frontales, scalene, or trapezius EMG activity may signal excessive breathing effort ( Khazan, 2013 ).…”

“…The six criteria provide a strategy for identifying potential resonance frequencies. There were two candidate resonance frequencies in Table 3 : 5.0 bpm for 53-bpm HR Max-HR Min and 5.5 bpm for 7°phase synchrony ( Shaffer, 2020 ).…”

The Effects of Heart Rate Variability Biofeedback on Functional Gastrointestinal Disorders: A Scoping Review

“…It is the frequency of breathing where the oscillation of heart rate due to the respiratory sinus arrhythmia (produced by the slow breathing) resonates with the oscillation in heart rate due to the baroreflex. This results in a maximal heart rate variation, and a maximal increase in baroreflex gain with an increase in baroreflex gain at resting states after consistent practice as well (Vaschillo, Vaschillo, and Lehrer 2006; P. M. Lehrer et al 2003;Fredric Shaffer 2020). The research into the benefit of employing resonance frequency into biofeedback training is limited, although an analogue study conducted in 2017 found that using a resonant frequency compared to a standardised breathing frequency was associated with a higher positive mood and a significantly higher LF/HF HRV ratio (Steffen et al 2017).…”