Heart Rate Variability Podcast

Below are the links to the studies and articles discussed in this episode: Personalized Respiratory Guidance for HRV: Lin, Z., Kong, W., Qiu, S., Luo, M., Wei, J., Guo, X., ... & Dan, G. (2025). High-precision personalized respiratory guidance model for enhanced breathing training: effects on heart rate variability. Biomedical Signal Processing and Control, 100, 108720. https://www.sciencedirect.com/science/article/abs/pii/S1746809425012315 Therapy with Local Anesthetics and HRV: Weinschenk, S., Topbas-Selcuki, N. F., Benrath, J., Strowitzki, T., & Feisst, M. (2025). Effects of therapy with local anesthetics (TLA) on heart rate variability (HRV) over 24 hours. Chronobiology International. https://www.tandfonline.com/doi/full/10.1080/07420528.2025.2560963?src=exp-la Veterans, Service Dogs, and HRV: Krause-Parello, C. A., Friedmann, E., Taber, D., Zhu, H., Quintero, A., & Yount, R. (2025). Veterans Training Service Dogs for Other Veterans: An Animal-Assisted Intervention for Post-Traumatic Stress Disorder. Behavioral Sciences, 15(9), 1180. https://www.mdpi.com/2076-328X/15/9/1180 Circadian Rhythm of HRV in Pregnancy: Rasouli, M., Feli, M., Azimi, I., Haghayegh, S., Sarhaddi, F., Niela-Vilen, H., ... & Rahmani, A. M. (2025). Circadian rhythm of heart rate and heart rate variability in pregnancy. npj Women's Health, 3(1), 57. https://www.nature.com/articles/s44294-025-00107-6 Wearable Tech in Tennis Players: Wang, Z. (2025). Integration of wearable technologies in monitoring physical performance and psychological stress in tennis players. Acta Psychologica, 260, 105706. https://www.sciencedirect.com/science/article/pii/S0001691825010194 Acoustic Features of Chants: Dolan, E. W. (2025, October 6). Chants across cultures share features that promote relaxation. PsyPost. https://www.psypost.org/chants-across-cultures-share-features-that-promote-relaxation/

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.

Welcome to the show notes for this week’s episode – This Week in HRV Edition. Below, you’ll find direct links to all the studies and articles discussed in this episode. These sources represent the latest research connecting HRV to mental health, resilience, environmental design, and leadership. Research Studies: Multisensory environmental effects on HRV and psychological restoration – Scientific Reports Walking through green and grey: Exploring sequential exposure and multisensory environmental effects on psychological restoration – Building and Environment The Impact of Vipassana Meditation on Health and Well-being: A Systematic Review of Current Evidence – Cureus Cardiac timing effects on response speed are modulated by blood pressure, but not by heart rate variability, in healthy young adults – Physiological Reports Heart-brain interaction in emotional regulation – Scientific Reports Environmental stress and HRV in agricultural settings – Agricultural and Forest Meteorology HRV and emotion regulation in depression risk – JAMA Psychiatry HRV modulation through breathing and neural coherence – Frontiers in Human Neuroscience News and Features: Professor honored for pioneering heart–brain research – UC Irvine News Solo practitioner uses HRV tech to improve patient care – Healthcare IT News What is heart rate variability and how can it guide smarter leadership decisions – Manila Bulletin HRV: The new secret weapon for heart resilience – Men’s Health Each of these studies and stories offers a unique perspective on how HRV connects the heart, brain, and body. For more insights, visit our website and subscribe to weekly updates on the evolving science of heart rate variability.

In this episode, we review seven new studies published between September 19 and September 25, 2025. Together, they highlight the many ways HRV intersects with brain activity, breathing practices, cardiac recovery, exercise environments, emergency medicine, environmental stressors, and new multimodal measurement approaches. We’ll explore: How brain networks and cognitive load shape HRV readings. Why slow breathing alone is powerful, and what feedback really adds. The Benefits of Yoga Nidra for Patients Recovering from Coronary Artery Bypass Surgery. How walking in natural environments provides a stronger autonomic boost than indoor or urban exercise. Real-world HRV findings in emergency medicine and why lab results don’t always translate. How pollution, heat, and noise suppress vagal tone. New frontiers in dynamic and multimodal HRV metrics. As always, I’ll connect the research to practical, client-ready strategies you can use right away. This podcast is sponsored by Optimal HRV. Learn more at optimalhrv.com. References  Behavioural Brain Research – Neural and cognitive influences on autonomic function. https://doi.org/10.1016/j.bbr.2025.115811 Psychophysiology – Comparing HRV biofeedback and slow-paced breathing. https://doi.org/10.1111/psyp.70156 Cureus – Impact of Yoga Nidra on heart rate variability in coronary artery disease patients undergoing coronary artery bypass grafting. https://www.cureus.com/articles/402202-impact-of-yoga-nidra-on-heart-rate-variability-in-coronary-artery-disease-patients-undergoing-coronary-artery-bypass-grafting-a-comparative-study Psychology of Sport and Exercise – Green exercise randomized controlled trial. https://doi.org/10.1016/j.psychsport.2025.102883 International Journal of Emergency Medicine – HRV in emergency medicine contexts. https://intjem.biomedcentral.com/articles/10.1186/s12245-025-00967-4 Environmental Research – Environmental stressors and their impact on HRV. https://doi.org/10.1016/j.envres.2025.122895 Preprint manuscript – Multimodal HRV analytics integrating respiration, voice, and movement. https://pmc.ncbi.nlm.nih.gov/articles/PMC8401087/#:~:text=HRV%20analysis%20is%20performed%20by,equipped%20with%20HRV%20analysis%20modules. 

Refrences: Ferreira S, Rodrigues M A, Mateus C, Rodrigues P P, Rocha N B. Interventions Based on Biofeedback Systems to Improve Workers’ Psychological Well-Being, Mental Health, and Safety: Systematic Literature Review. Journal of Medical Internet Research (2025). DOI: 10.2196/70134. JMIR+2JMIR+2 Lässing J, Wegener F, Höpker N, Hottenrott K, Gronwald T, Falz R. Heart rate variability response of intensity-matched strength training dependent on body position in females: a pilot randomized crossover study. Scientific Reports (2025). DOI: 10.1038/s41598-025-19817-7. Nature+1 Książek K, Masarczyk W, Głomb P, Romaszewski M, Buza K, Sekuła P, Cholewa M, Kołodziej K, Gorczyca P, Piegza M. Deep learning approach for automatic assessment of schizophrenia and bipolar disorder in patients using R-R intervals. PLoS Computational Biology (2025). DOI: 10.1371/journal.pcbi.1012983. PLOS+1 Zilcha-Mano S, Tchizick A, Nof A, Malka M, Oded Y. Clinical breakthroughs or research oversights? The imperative of integrating modalities to differentiate signal from noise. The British Journal of Psychiatry (First View, 2025). DOI: 10.1192/bjp.2025.10321. Cambridge University Press & Assessment Dear Media. “7 Lab Tests Every Woman in Her 30s Should Know, According to Dr. Sara Szal.” By Jane LaCroix. September 16, 2025. Dear Media

Discover how rhythmic muscle contractions can enhance heart rate variability (HRV) during breathing techniques. Learn the science behind baroreflex resonance and how specific contraction frequencies, like 6 per minute, optimize heart metrics. Explore the benefits of core recruitment and leg-crossing for amplified effects. Uncover practical guidelines for integrating contractions into your HRV training, including timing with breath and safe experimentation. Plus, see how contractions can improve focus and even rescue weak practice sessions!

This week’s episode of the Heart Rate Variability Podcast explores three new publications from September 5–11, 2025. We look at advances in contactless HRV monitoring using millimeter-wave radar, how physical fatigue alters time-domain and nonlinear HRV metrics, and a review of how accurate consumer wearables really are when tracking HRV. We dive into what these findings mean for clinicians, researchers, and anyone using HRV to track resilience, recovery, or performance. References Cui, Y., Zhang, W., Xu, J., Liu, Y., & Chen, H. (2025). Non-Contact Heart Rate Variability Monitoring with FMCW Radar via a Novel Signal Processing Algorithm. Sensors, 25(17), 5607. Read here Zhang, J., Niu, X., Wei, X., Ma, J., & Du, W. (2025). Effects of Induced Physical Fatigue on Heart Rate Variability in Healthy Young Adults. Sensors, 25(17), 5572. Read here Pramanik, P. (2025, September 8). Wearable health trackers reveal how accurate your smartwatch really is. News-Medical. Read here

References MacDonald, D. M., et al. (2025). Two-week heart rate variability measurements and lung health: A cross-sectional analysis in the ARIC Study. Respiratory Medicine, 234, 108338. https://www.resmedjournal.com/article/S0954-6111(25)00401-9/abstract Kamiya, Y., Saita, K., Kaneko, F., Li, J., & Okamura, H. (2025). Association between sense of coherence and phasic heart rate variability under psychosocial stress conditions. Physiology & Behavior, 298, 114969. https://www.sciencedirect.com/science/article/abs/pii/S0031938425001702?via%3Dihub European Society of Cardiology. (2025). How wearables are transforming remote monitoring of cardiovascular diseases. ESC 365 session page, ESC Congress 2025. Retrieved September 2025 from https://esc365.escardio.org/esc-congress/sessions/13953? Zhang, S., Niu, X., Ma, J., Wei, X., Zhang, J., & Du, W. (2025). Effects of sleep deprivation on heart rate variability: A systematic review and meta-analysis. Frontiers in Neurology, 16, 1556784.  https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2025.1556784/full Menuet, C., Ben-Tal, A., Linossier, A., Allen, A. M., Machado, B. H., Moraes, D. J. A., … Gourine, A. V. (2025). Redefining respiratory sinus arrhythmia as respiratory heart rate variability: An international expert recommendation for terminological clarity. Nature Reviews Cardiology.  https://www.nature.com/articles/s41569-025-01160-z

Featured Studies Wu, Y-R., Su, W-S., Lin, K-D., & Lin, I-M. (2025). Effect of Heart Rate Variability Biofeedback on Cardiac Autonomic Activation and Diabetes Self-Care in Patients with Type II Diabetes Mellitus. Applied Psychophysiology and Biofeedback, 50(3), 315–327. https://link.springer.com/article/10.1007/s10484-024-09666-x Kula, Y., Iversen, Z., Levine, A.D., & Gidron, Y. (2025). Does Vagal Nerve Activity Predict Performance in a Naval Commando Selection Test? Applied Psychophysiology and Biofeedback, 50(3), 349–357. https://link.springer.com/article/10.1007/s10484-025-09702-4 Addleman, J.S., Lackey, N.S., Tobin, M.A., et al. (2025). Heart Rate Variability Applications in Medical Specialties: A Narrative Review. Applied Psychophysiology and Biofeedback, 50(3), 359–381. https://link.springer.com/article/10.1007/s10484-025-09708-y Wu, D-W., Yang, P-C., & Lin, I-M. (2025). Effects of Heart Rate Variability Biofeedback on Pulmonary Indicators and HRV Indices Among Patients with COPD. Applied Psychophysiology and Biofeedback, 50(3), 383–394. https://link.springer.com/article/10.1007/s10484-024-09664-z Yang, P-C., Lin, I-M., & Wu, D-W. (2025). Effects of Heart Rate Variability Biofeedback on Enhancing Self-Efficacy, Quality of Life, and Six-Minute Walk Test in Patients with COPD. Applied Psychophysiology and Biofeedback, 50(3), 403–416. https://link.springer.com/article/10.1007/s10484-025-09689-y Bufo, M.R., Guidotti, M., Lemaire, M., et al. (2025). Autonomic Disequilibrium at Rest in Autistic Children and Adults. Applied Psychophysiology and Biofeedback, 50(3), 465–480.https://link.springer.com/article/10.1007/s10484-025-09696-z Chakraborty, H., Vinay, A.V., Sindhu, R., & Sinha, R. (2025). Exploring the Immediate Effects of Nadi Shuddhi Pranayama on Heart Rate Variability Among Young Adults. Applied Psychophysiology and Biofeedback, 50(3), 525–533. https://link.springer.com/article/10.1007/s10484-025-09710-4 Liu, Z., Zheng, S., Wang, H., & Wang, H. (2025). Acute Effects of Resonance Breathing on Skin Sympathetic Nerve Activity and Heart Rate Variability in Healthy Adults. Applied Psychophysiology and Biofeedback, 50(3), 535–545. https://link.springer.com/article/10.1007/s10484-025-09711-3 Dewig, H.G., Cohen, J.N., Renaghan, E.J., et al. (2024). Are Wearable Photoplethysmogram-Based Heart Rate Variability Measures Equivalent to Electrocardiogram? A Simulation Study. Sports Medicine, 54(12), 2927–2934. https://link.springer.com/article/10.1007/s40279-024-02066-5 Reynolds, G. (2025, August 19). This often-ignored smartwatch health metric can help you manage stress. The Washington Post – Well+Being. https://www.washingtonpost.com/wellness/2025/08/19/heart-rate-variability-stress-longevity/ Filchenko, I., et al. (2025, June). Heart rate variability during sleep as an early warning sign of future stroke, depression, and cognitive decline. EAN Congress 2025 presentation, reported by News-Medical. https://www.news-medical.net/news/20250620/Study-links-sleep-heart-rate-variability-to-stroke-and-depression-risk.aspx#:~:text=Study%20links%20sleep%20heart%20rate,to%20stroke%20and%20depression%20risk  

In this episode, Matt Bennett welcomes Jarhed Peña Jarhed to the show to discuss how he discovered and applies heart rate variability and HRV biofeedback into his therapeutic work. We cover a wide range of typics, research, and applications of HRV.  http://recoveryandbalance.com/