In this episode of the Heart Rate Variability Podcast, host Matt Bennett sits down once again with Dr. Inna Khazan, a leading expert in HRV biofeedback and applied psychophysiology. Together, they unpack one of the most fascinating and misunderstood aspects of heart rate variability — low-frequency HRV — and its connection to self-regulation, stress resilience, and overall wellness. Understanding Frequency Domains in HRV Dr. Khazan begins by breaking down the concept of frequency domains in HRV. Just as white light contains multiple colors, the heart rate signal is composed of several distinct frequency components. Using tools like the Fast Fourier Transform, researchers can separate heart signals into high-frequency, low-frequency, and very-low-frequency ranges — each linked to specific physiological processes and parts of the autonomic nervous system. Low Frequency HRV and the Baroreflex The conversation dives deep into low-frequency power, which represents the interplay between the baroreflex (the body’s blood pressure regulation system) and the vagus nerve. Dr. Khazan explains how resonance-frequency breathing—typically practiced for 20 minutes a day—acts like strength training for these systems. Over time, this practice enhances emotional regulation, stress recovery, and overall heart-brain coherence. Why Breathing Rate and Context Matter Listeners learn that breathing too long in a low-frequency state can actually suppress other important HRV components, such as high-frequency and very-low-frequency power. Instead, Dr. Khazan recommends brief, consistent training sessions to balance all aspects of the nervous system. She also clarifies common misconceptions, including the outdated idea that low-frequency HRV measures sympathetic activity, emphasizing instead its parasympathetic and baroreflex origins. Making Sense of HRV Metrics in Optimal HRV Matt and Dr. Khazan discuss Optimal HRV’s “Optimal Zone” scale, which tracks the percentage of time users spend in low-frequency dominance during a session. They also unpack metrics like Max-Min and total low-frequency power, explaining how they interact and what each reveals about training efficiency and day-to-day readiness. Practical Takeaways Practice resonance-frequency breathing for 20 minutes a day to enhance self-regulation. Avoid over-training in the low-frequency zone — balance is key. Understand that low-frequency HRV is not a measure of stress or sympathetic activity, but rather a reflection of vagal and baroreflex strength. Leverage your Optimal HRV app metrics to track progress, focus, and nervous-system adaptability. Listen & Learn More Explore more insights from Dr. Khazan and Matt Bennett on heart rate variability, stress regulation, and biofeedback science. Visit OptimalHRV.com for resources, show notes, and upcoming episodes, including the "This Week in HRV" series, which highlights the latest HRV research and applications.