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

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.