In this episode of the Heart Rate Variability Podcast, Matt Bennett sits down with Dr. Patrick K. Porter, PhD, founder of BrainTap®, to explore the connection between brainwave activity, heart rate variability, breathwork, and nervous system regulation.

Dr. Porter shares how his interest in brainwave training began at an early age and how decades of work in neuroscience-based performance ultimately led to the development of BrainTap. His background includes extensive work in brainwave entrainment and non-invasive approaches to supporting brain health and human performance.

In this conversation, Matt and Dr. Porter discuss how HRV can be used as a practical measure of nervous system activity, why chronic high-stress states may affect cognitive performance and recovery, and how intentional practices can help shift the body toward more regulated states.

They also explore:
- Brainwave states including beta, alpha, theta, gamma, delta, and SMR
- The relationship between HRV, brain activity, and autonomic regulation
- Brainwave entrainment compared with neurofeedback
- Breathwork practices for different times of the day
- Vagal stimulation and simple nervous-system regulation techniques
- BrainTap research related to pain, stress, cognitive performance, and recovery
- Dr. Porter’s personal routine for supporting brain and nervous system health
- How AI may influence the future of personalized brain fitness

Dr. Porter also shares his perspective on where brain optimization is headed—from clinics and universities to schools, workplaces, and personalized digital coaching.

Whether you’re interested in HRV, neuroscience, biofeedback, breathwork, stress regulation, or improving human performance, this conversation offers a fascinating look at how the brain and autonomic nervous system may work together.

Learn more about Optimal HRV: https://www.optimalhrv.com
Learn more about BrainTap: https://braintap.com

This podcast is for educational purposes only and is not intended to provide medical advice, diagnosis, or treatment.

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history.

This week on This Week in Heart Rate Variability, we explore the theme of Performance. Seven studies this week cover urban air pollution, shift work, weighted vests, functional clothing, ergogenic supplementation, elite athlete aging, and real-time exercise intensity classification with DFA-alpha-1.

1. Combined mask and headphone use significantly improves HRV during traffic exposure: a randomized crossover RCT

PUBLICATION: Journal of Hazardous Materials
AUTHORS: Meng, Qi, Wang, and Duan

KEY FINDING: In a randomized crossover study, 51 healthy young adults (mean age 20, ~40% female) were exposed to four 2-hour conditions at a high-traffic site in Beijing: no intervention, KN95 mask alone, noise-canceling headphones alone, and both combined. Single interventions did not yield a significant HRV benefit. The combined intervention significantly elevated SDNN (+20.3%), RMSSD (+56.8%), SDSD (+62.0%), pNN50 (+61.1%), LF (+128.6%), and HF (+73.8%) relative to control. It also reduced the myocardial injury marker CK-MB by 27.6% and homocysteine by 79.5%. Females showed greater autonomic benefits than males.

SIGNIFICANCE: This finding has real implications for urban athletes and anyone training in polluted environments. Wearing just one intervention (mask or headphones) alone did not provide significant protection, but the combined approach demonstrated robust cardiovascular protection during traffic exposure.

Read the full study

2. Night shift workers show elevated heart rate fragmentation independent of traditional HRV changes: MESA Sleep cohort

PUBLICATION: Chronobiology International
AUTHORS: Multi-Ethnic Study of Atherosclerosis Sleep study cohort analysis

KEY FINDING: A cross-sectional analysis of 845 participants (mean age 64, 51% women) compared heart rate variability and heart rate fragmentation (HRF) across shift types. Night and rotating shift workers had significantly higher PAS - the percentage of normal-to-normal intervals in alternation segments - compared to day workers (+11.9%, 95% CI 1.8-22.0). Traditional HRV metrics showed minimal and inconsistent differences. Sleep duration modified the effect: the PAS difference was most pronounced in short sleepers (+20.4%) and reversed in long sleepers (-10.8%, interaction p=0.06).

SIGNIFICANCE: The surprising finding is that traditional HRV showed almost no difference between night-shift and day-shift workers. But a newer metric called heart rate fragmentation - specifically PAS, the percentage of intervals in alternation segments - was significantly elevated in night/rotating shift workers. Sleep duration modulated the severity of that fragmentation, suggesting that this metric captures autonomic stress that standard HRV indices miss.

Read the full study

3. Weighted vest use increases cardiovascular workload and transiently suppresses HRV during active wearing, with more pronounced effects in females: ATLAS RCT sub-study

PUBLICATION: Physiological Reports
AUTHORS: Bellman, PA Jansson, JO Jansson, Ohlsson, and Bergfeldt

KEY FINDING: In a proper RCT sub-study, 51 adults with class I obesity (BMI 30-35) wore either a high-load vest (11% of body weight) or a low-load vest (1% of body weight) for 8+ hours/day for 15 days. During the afternoon active-wearing period, the high-load group showed significantly higher HR (+7%), higher %HRR (+6%), lower SDNN (p=0.01), and lower RMSSD (p=0.002). In females specifically, high-load wearing significantly reduced RMSSD, high-frequency power, and elevated the LF/HF ratio. Resting morning and nighttime measurements were unchanged, suggesting no sustained autonomic adaptation over 15 days.

SIGNIFICANCE: Use of a weighted vest during afternoon active wear led to significant HRV suppression and an elevated heart rate. The autonomic suppression was more pronounced in women. The lack of change in resting HRV (morning and night) suggests the body did not develop sustained adaptation over 15 days of wear, indicating the suppressive effect was transient and activity-dependent.

Read the full study

4. Black-silica clothing shows no significant HRV effects in a small, uncontrolled, industry-funded pilot: a case study in critical appraisal

PUBLICATION: Physiologia
AUTHORS: Tainaka (Niigata University)

KEY FINDING: In an unblinded, uncontrolled, fixed-order pilot study, 10 adults wore comparator garments (Day 1) and then black-silica-containing BS Fine clothing (Day 2). Garment conditions were not compositionally matched. After Holm correction for multiple comparisons, no HRV outcome reached statistical significance (all Holm p >= 0.797). A modest leg surface temperature increase (0.668 degrees C) did not survive correction (Holm p=0.100). A secondary total-power dispersion finding was not confirmed in the n=9 sensitivity analysis.

SIGNIFICANCE: The methodological problems are significant - small sample, no blinding, unmatched conditions, single-order design. However, what makes this study valuable is the author's own honest conclusion: "cannot isolate an effect attributable specifically to black silica or demonstrate autonomic benefit." This serves as a useful template for reading product-sponsored HRV research critically and understanding the limits of poorly controlled pilot studies.

Read the full study

5. Acute theacrine supplementation does not significantly alter post-resistance-exercise HRV versus placebo: a randomized pilot crossover

PUBLICATION: Journal of Vascular Diseases
AUTHORS: Ramos Souza, Nascimento Consoli, Weber, Campos, Diogo Ferreira, and de Oliveira (UFRJ, Macaé)

KEY FINDING: In a double-blind crossover trial, 17 resistance-trained young adults (8 female) received 200 mg of theacrine (TEA) or placebo, taken 90 minutes before performing 5 sets of back squats at 85% of 10RM. The placebo condition showed significant post-exercise drops in RMSSD, HFnu, and SDNN. TEA condition did not show a significant pre-supplementation to post-exercise RMSSD reduction. Critically, the time x condition interaction was not significant (p=0.246, eta-squared=0.043), meaning the between-condition difference was not statistically confirmed.

SIGNIFICANCE: The moderate effect size for post-exercise RMSSD warrants a larger confirmatory trial. While the trend suggests theacrine may attenuate post-exercise HRV suppression, the interaction term remains unconfirmed, so we cannot yet claim a protective effect. This is a rigorous negative finding that illustrates the importance of checking interaction statistics, not just main effect trends.

Read the full study

6. Younger professional soccer players show higher HRmax and a trend toward higher RMSSD despite identical training loads: wrist PPG monitoring study

PUBLICATION: Electronics
AUTHORS: Takai, Morikawa, and Yuda

KEY FINDING: In a wrist PPG monitoring study, 14 Japanese professional soccer players - 7 aged 23 or younger and 7 aged 24 or older - were monitored throughout a training season. Maximum heart rate was robustly higher in the younger group (Hedges' g=2.02, FDR-corrected p<0.05). RMSSD was also higher in younger players, but this finding did not survive FDR correction and is classified as exploratory. Training load was statistically identical across age groups.

SIGNIFICANCE: The HRmax finding is solid and has real implications for age-adjusted monitoring in elite athletic cohorts. The study highlights the importance of age-adjusted HRV interpretation even when players train identically. Limitations include n=14, a single club, a cross-sectional design, and the risk of wrist PPG motion artifacts, but the core finding on HRmax is robust and actionable.

Read the full study

7. DFA-alpha-1 classifies exercise modality and intensity with 88-98% accuracy, but values are unexpectedly elevated during intermittent protocols: implications for real-time monitoring

PUBLICATION: PLoS One
AUTHORS: Sanchez, Favier, Fabre, and Varray

KEY FINDING: In 26 healthy adults completing three cycling protocols (continuous 40% MAP, continuous 60% MAP, and intermittent alternating 75%/25% MAP), combined use of mean RR, SDNN, and DFA-alpha-1 classified exercise type with 88-98% sensitivity and specificity. Critically, DFA-alpha-1 during the intermittent session was unexpectedly higher (~0.8) than during continuous 60% MAP (~0.5), because recovery intervals allowed rapid DFA-alpha-1 recovery.

SIGNIFICANCE: If you're monitoring DFA-alpha-1 during interval sessions, this context is essential. DFA-alpha-1 values during recovery intervals can appear in the "aerobic zone" (~0.8) even when overall session load is high. The relationship between DFA-alpha-1 and intensity holds for continuous exercise; contextualizing readings against workout structure is essential for accurate interpretation during HIIT.

Read the full study

The Optimal HRV app is built around a simple morning measurement, taken at the same time each day, so that consistency turns a single number into a meaningful signal over time. Over weeks and months, you earn your own baseline - not someone else's - so you can see when your body needs rest, when it's ready for training, and when it's simply having an off day. The app also includes biofeedback tools with guided, paced breathing to help you influence your nervous system in real time, and gentle in-app education so you're learning the rhythm your system is measuring.

Learn More

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history.

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history.

This week on This Week in Heart Rate Variability, we open a new themed month by looking at where heart rate variability is headed next. Six studies map the future of the field — from a unifying theory of cardiovascular instability built on Shannon entropy, to the regulatory and technical realities of validating consumer wearables, to a meta-analysis quantifying how far photoplethysmography still is from true electrocardiography-derived HRV, to a virtual reality study, a forest-based multimodal field study, and a deep dive into the asymmetric structure of the heartbeat itself.

RESEARCH HIGHLIGHTS THIS WEEK

1. Shannon Entropy in Heart Rate Variability: A Unified Indicator of Electrical and Hemodynamic Cardiovascular Instability

PUBLICATION: Medical Research Archives

AUTHORS: Orazio Antonio Barra

KEY FINDING: This systematic review pooled 22 published studies that applied Shannon entropy of RR intervals to atrial fibrillation and tilt-induced syncope. Entropy declined progressively across both conditions — roughly ten percent at baseline instability, fifteen to twenty percent approaching pre-crisis, and twenty-five to thirty percent as crisis became imminent — with entropy showing better specificity than other HRV indices while holding onto its sensitivity.

SIGNIFICANCE: Entropy looks less like a metric tied to one specific condition and more like a general-purpose marker of autonomic complexity loss that shows up consistently whether the underlying instability is electrical or hemodynamic. This is a synthesis of existing studies rather than a new trial, so it should be read as a strong, well-supported hypothesis rather than a validated bedside tool.

Read the full study:

https://esmed.org/MRA/mra/article/view/7606

2. Validity, Reliability, and Regulatory Considerations for Consumer Devices in Clinical Research Data Collection

PUBLICATION: Applied Clinical Trials Online

AUTHORS: Lauren Crooks, Greta Marie van Schoor, Anthony Everhart, Bill Byrom, and Thijs Sondag

KEY FINDING: This article maps the validity, reliability, and regulatory landscape for consumer wearables used in decentralized clinical trials. Heart rate accuracy can approach ECG-level concordance under favorable conditions, but motion artifacts, device-to-device variation, and demographic performance gaps can cause aggregate agreement statistics to mask large individual-level errors. Only an estimated 11% of devices on the market have been rigorously and publicly validated.

SIGNIFICANCE: Regulators are converging on "fit-for-purpose" validation rather than universal accuracy claims — asking whether a specific device is accurate enough for a specific clinical question, not whether it's accurate for everything. That's a useful discipline for anyone using consumer devices outside a formal trial, too.

Read the full study:

https://www.appliedclinicaltrialsonline.com/view/validity-reliability-regulatory-considerations-consumer-devices-clinical-research-data-collection

3. Accuracy of Photoplethysmography-Derived Pulse Rate Variability Compared with Electrocardiography-Derived Heart Rate Variability: A Systematic Review and Meta-Analysis

PUBLICATION: Sensors

AUTHORS: Shiwen Xu, Hao Liu, Zhengliang Liu, Peng Su, and Zhuangzhuang Gu

KEY FINDING: Pooling 43 studies, this meta-analysis found absolute standardized mean differences of about 19% for RMSSD and 13% for SDNN when comparing PPG-derived pulse rate variability with ECG-derived HRV. Results were drawn from resting, controlled conditions only.

SIGNIFICANCE: PPG and true HRV are not interchangeable, and the authors explicitly caution against generalizing these best-case accuracy numbers to sleep, exercise, stress, or free-living conditions — where PPG accuracy is likely to be worse, not better. PPG remains attractive for continuous, low-burden monitoring, but the absolute numbers deserve real caution outside of rest.

Read the full study:

https://www.mdpi.com/1424-8220/26/16/5192

4. Virtual Reality and Mental Stress: Linear, Non-Linear, and Machine Learning Analysis of Heart Rate Variability

PUBLICATION: Technologies

AUTHORS: Penio Lebamovski and Evgeniya Gospodinova

KEY FINDING: In 42 healthy volunteers exposed to a stress-inducing VR game under low-immersion (polarizing glasses) and high-immersion (VR headset) conditions, HRV responses differed meaningfully between immersion technologies. Nonlinear methods (Poincaré and recurrence plots) captured structural changes that linear metrics missed, and a Random Forest model using 17 HRV parameters successfully classified resting versus immersive states.

SIGNIFICANCE: The level of sensory immersion doesn't just intensify the stress response — it appears to shape its character. This is a modest, controlled lab sample, so it's a proof of concept rather than a deployable tool, but it points toward VR-calibrated biofeedback and exposure-therapy applications with objective physiological readouts.

Read the full study:

https://www.mdpi.com/2227-7080/14/8/487

5. Neural Dissociation of Cognitive Effort and Physiological Arousal: Multimodal Single-Channel EEG, Cortisol, and HRV Evidence from an Ecologically Valid Field Study

PUBLICATION: International Journal of Psychophysiology

AUTHORS: Neta B. Maimon, Ganit Baruchin, Itamar Grotto, Nathan Intrator, Lior Molcho, Talya Zeimer, Ofir Chibotero, Gal Levi, Hagit Cohen, Merav Greenstein, and Efrat Danino

KEY FINDING: In a forest-based field study of 101 healthy adults completing an auditory cognitive battery, EEG arousal showed a graded hierarchy (startle, then emotional, then mental load, then rest, in descending order), while a regulatory EEG feature (T2) was selectively suppressed during mental load but not during acute stress. Higher baseline cortisol negatively predicted arousal but positively predicted cognitive recruitment. Neural complexity features predicted reduced HRV three hours later; the T2 feature predicted self-reported anger.

SIGNIFICANCE: Cognitive effort and physiological arousal are dissociable, not the same phenomenon wearing different names. This is a correlational field study, not an experiment establishing causation, and the rich multi-channel design carries a real risk of findings that don't replicate — but it's a compelling case for multimodal, rather than single-signal, stress screening.

Read the full study:

https://www.sciencedirect.com/science/article/abs/pii/S0167876026001042?via%3Dihub

6. The Asymmetry of Deceleration Input into the Heart Rate Transitions - A Study Over Healthy Subjects in Head-Up Tilt

PUBLICATION: Biocybernetics and Biomedical Engineering

AUTHORS: Rafał Pawłowski, Paweł Zalewski, and Katarzyna Buszko

KEY FINDING: In 151 healthy men undergoing head-up tilt testing, 60.3% of resting supine heart rate signals showed measurable heart rate asymmetry. The relationships between asymmetry metrics and standard time/frequency-domain HRV metrics were nonlinear. A newly proposed metric, Deceleration Input (DI), outperformed existing asymmetry indices (Porta, Guzik, Ehlers, Slope) in resistance to outliers.

SIGNIFICANCE: Heart rate asymmetry is a normal feature of a healthy resting rhythm, not a rare anomaly, and it appears to carry information that the standard symmetric-assuming metrics can't see. This was studied only in healthy men using a single provocation (tilt), so generalization to other populations and stressors remains open — but it's a strong argument that nonlinear, geometric analysis is where a meaningful share of future HRV research is headed.

Read the full study:

https://www.sciencedirect.com/science/article/pii/S0208521626000550

KEY THEMES

Taken together, this week's six studies point toward the same conclusion from six different angles: the future of heart rate variability isn't a single new metric; it's better measurement. Shannon entropy offers a unifying way to think about autonomic complexity across different kinds of cardiovascular crises, while the wearable validation and photoplethysmography meta-analysis both push back, with real numbers, on the assumption that any device labeled "HRV" measures the same thing an ECG measures.

Methodology matters as much as the finding itself. Honest cross-validation and disciplined preprocessing are what separate a useful signal from a headline artifact — a theme that shows up explicitly in the wearables and PPG studies, and implicitly in how carefully the VR and forest-field studies had to be designed just to isolate what they were actually measuring.

Increasingly, the interesting information seems to live outside the numbers most of us are used to reading. Nonlinear, geometric methods captured structure in the VR study that linear metrics missed entirely, and the heart rate asymmetry study revealed meaningful information in the simple fact that the heart doesn't speed up and slow down symmetrically. The nervous system is best understood through its flexibility — and capturing that flexibility well is where this field is headed next.

SPONSORED BY OPTIMAL HRV

The Optimal HRV app is built around a simple morning measurement, taken at the same time each day, so that consistency turns a single number into a meaningful signal over time. Over weeks and months, you earn your own baseline — not someone else's — so you can see when your body needs rest, when it's ready for training, and when it's simply having an off day. The app also includes biofeedback tools with guided, paced breathing to help you influence your nervous system in real time, and gentle in-app education so you're learning the rhythm your system is measuring.

Learn More: www.optimalhrv.com

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history.

In this follow-up episode of the Heart Rate Variability Podcast, Matt Bennett reconnects with Lieven Van Linden to discuss the newly published English version of his book, Fully Charged. Since their last conversation two years ago, Lieven’s work has continued to evolve at the intersection of leadership, nervous system regulation, sustainable performance, and HRV.

Lieven shares how his engineering background shaped the framework behind Fully Charged, applying process improvement thinking to human performance. Rather than treating energy, resilience, and leadership as vague concepts, his model looks at the body as a system with inputs, processes, outputs, and measurable feedback. HRV plays a central role as a biomarker for nervous system health, recovery, and available energy.

Matt and Lieven also explore what has changed since the book's original publication, including new English-language chapters on artificial intelligence and women's energy levels. Lieven reflects on the slower-than-expected adoption of HRV technology in Europe and the growing conversation around AI health coaches. While AI can support education and insight, Lieven emphasizes that human connection remains essential for lasting behavioral change.

The conversation also moves into Lieven’s personal evolution. After years of extreme endurance racing, he has shifted toward freediving, which challenges him in a very different way. Rather than pushing through suffering, freediving requires relaxation, self-regulation, inner awareness, and trust in the body.

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history.

This week on This Week in Heart Rate Variability, we open our second themed month with a focus on medical health. Six studies map how heart rate variability behaves under real medical strain — from a rigorous methodological look at glucose sensing, to a two-decade cohort tracking cardiovascular mortality, to hidden autonomic signals in normal brain recordings, to the flattening and even reversal of breath-heart coupling in brain-injured intensive care patients, to a call for multi-window autonomic assessment in critically ill cancer patients, and finally to autonomic flexibility as a biomarker for fatigue in multiple sclerosis. A quick reminder that this is the newly curated, theme-based format we kicked off last month, and this week's center of gravity is medical health.

RESEARCH HIGHLIGHTS THIS WEEK

1. Re-evaluating heart rate variability biomarkers for glucose sensing: the impact of age normalization and subject-independent validation

PUBLICATION: BMC Medical Informatics and Decision Making

AUTHORS: Md Basit Azam, Sarangthem Ibotombi Singh

KEY FINDING:

In a rigorously validated model built on data from forty-three men with type two diabetes, heart rate variability features derived from the electrocardiogram showed a modest but significant association with hemoglobin A1c (R-squared of about zero point two two), while none of the six tested age-normalization methods improved model performance — suggesting age-related decline in heart rate variability was not confounding the signal.

SIGNIFICANCE:

This study is a piece of methodological conscience in the wearable glucose monitoring space. It shows that heart rate variability carries a real but modest signal for glycemic status, that honest subject-independent validation is essential, and that a fashionable statistical correction is not worth adding until you have checked whether it actually helps.

Read the full study:

https://pmc.ncbi.nlm.nih.gov/articles/PMC13169770/

2. Differential associations of resting heart rate and heart rate variability indices with cardiovascular and coronary heart disease mortality risk: the prospective KORA study

PUBLICATION: Scientific Reports

AUTHORS: Kolade Oluwagbemigun, Dan Ziegler, Alexander Strom, Margit Heier, Gidon J. Bönhof, Michael Roden, Wolfgang Rathmann, Christa Meisinger, Annette Peters, Stefanie M. Hauck, Agnese Petrera, Moritz F. Sinner, Stefan Kääb, Barbara Thorand, Christian Herder

KEY FINDING:

In a prospective German cohort followed for more than two decades, higher resting heart rate was associated with greater cardiovascular and coronary heart disease mortality across the whole group, while the relationships between heart rate variability indices and mortality differed by glucose status — including an S-shaped, nonlinear association between the root mean square of successive differences and cardiovascular mortality in people with type two diabetes.

SIGNIFICANCE:

The metabolic context changes the meaning of the measurement. The same heart rate variability index does not convey the same message in a person with normal blood sugar as in a person with diabetes, and greater variability is not always better. Long-cohort work like this reframes heart rate variability as a context-dependent marker rather than a universal one.

Read the full study:

https://www.nature.com/articles/s41598-026-66516-y

3. Heart Rate Variability During Short-Term Electroencephalography

PUBLICATION: Cureus

AUTHORS: Miles S. Evans, Catarina De Marchi Assunção, Vishwanath Sagi

KEY FINDING:

In a retrospective single-center analysis of one hundred and three adults whose brain recordings had been read as normal, heart rate variability measured from the electrocardiogram channel during the first five minutes of wakefulness — including the root mean square of successive differences and the standard deviation of the normal-to-normal intervals — was significantly lower than published reference values.

SIGNIFICANCE:

A test can return normal on the dimension it was designed to measure and still be quietly carrying important information on another dimension entirely. Heart rate variability, essentially free to extract from an existing recording, may reveal subclinical autonomic dysfunction in people whose brain recordings appear reassuring.

Read the full study:

https://www.cureus.com/articles/407343-heart-rate-variability-during-short-term-electroencephalography

4. Alterations in respiratory heart rate variability in brain-injured neurointensive care unit patients compared with healthy humans

PUBLICATION: Clinical Neurophysiology

AUTHORS: Valentin Ghibaudo, Gwendan Percevault, Samuel Garcia, Hugo Ardaillon, Nathalie Buonviso, Clément Menuet, Baptiste Balança

KEY FINDING:

In 55 brain-injured neurointensive care unit patients compared with 31 healthy volunteers, the amplitude of respiratory heart rate variability collapsed from a median of about 6 beats per minute in controls to about 1 beat per minute in patients, and the coupling frequently inverted, so that peak heart rate occurred during expiration rather than inspiration. Mechanical ventilation and deeper sedation were associated with further reductions in amplitude.

SIGNIFICANCE:

The elegant coupling of breath and heartbeat, which most healthy people never notice, can flatten and even reverse when the brainstem is under siege. This offers a potential bedside physiological marker for tracking autonomic and neurological recovery in some of the most fragile patients in medicine.

Read the full study:

https://hal.science/hal-05603882

5. Autonomic nervous system dysfunction in critically ill cancer patients: Hemodynamic consequences and multimodal assessment strategies

PUBLICATION: Cancer Pathogenesis and Therapy

AUTHORS: Shiyi Gong, Yun Chu, Xiaoting Wang

KEY FINDING:

This narrative review argues that autonomic dysfunction in critically ill cancer patients should be assessed through several complementary windows — heart rate variability, blood pressure variability, baroreflex sensitivity, multimodal monitoring, and machine-learning-assisted analysis — rather than through any single measurement, and situates this within a Host-Organ Unregulated Response framework.

SIGNIFICANCE:

Heart rate variability is a valuable voice, but only one voice, in the choir of autonomic assessment. In the sickest patients, whose regulation is being disrupted from many directions at once, a multi-window, multi-signal approach paired with careful analytic tools is more likely to capture what is actually happening than any single index.

Read the full study:

https://www.sciencedirect.com/science/article/pii/S2949713226000406

6. Heart rate variability as a biomarker of autonomic (re)activity and fatigue in multiple sclerosis

PUBLICATION: Multiple Sclerosis and Related Disorders

AUTHORS: Guadalupe Garis, Carina Sander-Sandersfeld, Andrea Hildebrandt, Helmut Hildebrandt

KEY FINDING:

In pooled data from two clinical trials totaling seventy-eight participants with multiple sclerosis, heart rate variability parameters resolved into a two-factor structure — one primarily parasympathetic, one primarily sympathetic — with differing responses to self-alert training, deep breathing, and progressive muscle relaxation, and with a smaller change in the standard deviation of the normal-to-normal intervals during a sustained attention task predicting higher trait fatigue.

SIGNIFICANCE:

This study reframes chronic multiple sclerosis fatigue as, in part, a failure of autonomic flexibility — a nervous system that has lost some of its capacity to rise to a demand and then recover — and points to heart rate variability as a noninvasive way to monitor autonomic modulation during interventions designed to help.

Read the full study:

https://www.sciencedirect.com/science/article/pii/S2211034826004840

KEY THEMES

SPONSORED BY OPTIMAL HRV

The Optimal HRV app is built around a simple morning measurement, taken at the same time and in the same way each day, so that consistency turns a single number into a meaningful signal. Over weeks and months, you watch your own trend line — how you absorb training, how you handle stress, how you recover from illness — rather than chasing a good score on a good day. The app also includes biofeedback tools with guided, paced breathing to help you find the rhythm at which your heart rate variability responds most strongly, so you can gently train the nervous system you are learning to measure.

Learn More: www.optimalhrv.com

Medical disclaimer: The information shared on this podcast is for educational and informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional guidance from a qualified healthcare provider. If you have questions about your health or a medical condition, please consult a licensed clinician who knows you and your history.

Medical disclaimer: This podcast is for informational and educational purposes only and does not constitute medical advice. Please consult your healthcare provider before making any changes based on this content.

Welcome to This Week in Heart Rate Variability. This is the next installment in our newly curated, theme-based format, and this week's theme is mental health: what the rhythm of the heart can—and cannot—tell us about the mind. Across seven studies, a single thread keeps surfacing: the body's story and the mind's story refuse to line up neatly. Sometimes lower heart rate variability marks distress; sometimes it does not move where we most expect it to; and in at least one striking case, higher variability marks not health but trouble.

RESEARCH HIGHLIGHTS THIS WEEK

1. A meta-analysis of heart rate variability and psychopathology: An investigation guided by the hierarchical taxonomy of psychopathology framework

PUBLICATION: Journal of Psychopathology and Clinical Science

AUTHORS: Tam Pham, Carly J. Johnco, Ana Neves, Wilson P. H. Lim, Gladys J. Heng, Rachel Ygnacio, Miriam K. Forbes

KEY FINDING:

Pooling 430 studies (732 effect sizes across roughly 62,000 people), lower resting heart rate variability was associated with most of the psychopathology hierarchy — including schizophrenia, bipolar disorder, autism, generalized anxiety disorder, panic disorder, borderline personality disorder, post-traumatic stress disorder, and major depression — but not with obsessive-compulsive disorder, social anxiety disorder, or attention-deficit/hyperactivity disorder. Associations were strongest in psychotic conditions and consistently stronger in more severely symptomatic samples.

SIGNIFICANCE:

Reduced heart rate variability looks less like a disorder-specific fingerprint and more like a transdiagnostic marker of systemic dysregulation tied to illness severity — a fever, not a rash. It may be most useful for gauging overall strain and tracking change over time rather than sorting people into diagnoses. This is a meta-analysis of largely cross-sectional data, so it shows association, not causation.

Read the full study:

https://pubmed.ncbi.nlm.nih.gov/42490257/

2. Heart rate variability and risk of agitation in Alzheimer's disease: the Atherosclerosis Risk in Communities Study

PUBLICATION: Brain Communications

AUTHORS: Kathy Y. Liu, Eric A. Whitsel, Gerardo Heiss, Priya Palta, Suzanne Reeves, Feng V. Lin, Mara Mather, Jonathan P. Roiser, Robert Howard

KEY FINDING:

In 120 participants from the Atherosclerosis Risk in Communities study whose dementia was attributed solely to Alzheimer's disease, higher heart rate variability was associated with greater agitation risk, with the strongest signal coming from the change in vagally mediated variability over roughly two decades. The associations were adjusted for cognitive status, resting heart rate, demographics, comorbidities, and medications affecting the autonomic nervous system.

SIGNIFICANCE:

The meaning of heart rate variability is context-dependent: in a brain undergoing neurodegeneration, an increase in autonomic signal may reflect a loss of regulatory control rather than resilience. This is a candidate marker of propensity for agitation, not yet a clinical tool. Observational design and a small subgroup mean this is association, not causation.

Read the full study:

https://academic.oup.com/braincomms/article/5/6/fcad269/7311113?login=false

3. Physiological correlates of interoception and the effect of heart rate variability biofeedback

PUBLICATION: Frontiers in Network Physiology

AUTHORS: Andy Schumann, Lisa Schmitt, Katrin Rieger, Elif Çalışkan, Feliberto De la Cruz, Maria Geisler, Yubraj Gupta, Karl-Jürgen Bär

KEY FINDING:

After eight weeks of home-based heart rate variability biofeedback in 25 healthy adults, respiratory sinus arrhythmia and baroreflex sensitivity increased, and breathing rate fell. Interoceptive accuracy (heartbeat counting) improved only modestly, from about 43 percent to about 51 percent, while the clearest interoceptive gain was in self-regulation — the felt sense of being able to steady oneself.

SIGNIFICANCE:

The benefit of biofeedback may lie more in cultivating a sense of self-regulatory agency than in sharpening raw bodily accuracy. This was a single-arm study with no control group and a small healthy sample, so a controlled trial in a clinical population is the needed next step.

Read the full study:

https://pmc.ncbi.nlm.nih.gov/articles/PMC13368545/

4. Psychoneuroimmunological Predictors of PTSD in ICU Patients

PUBLICATION: International Nursing Research Congress (Sigma Theta Tau International)

AUTHORS: Yu-Ju Chen, Pei-Yu Hou, Ching-I Li

KEY FINDING:

Among 73 abdominal-surgery intensive care unit patients, about 18 percent developed post-traumatic stress disorder. Higher heart rate variability (the standard deviation of normal-to-normal intervals) at discharge and at three months was protective, whereas anxiety at discharge and early elevations in C-reactive protein raised risk; delirium in the unit and infrequent family visits were also predictors. Anxiety and heart rate variability measured at discharge together accounted for about 60 percent of the variation in who developed post-traumatic stress disorder.

SIGNIFICANCE:

Intensive care unit discharge may be a critical, low-cost screening window, and the presence of family at the bedside may be measurably protective. This is a conference poster, not a peer-reviewed article, based on a small, single-center sample in which the model was tested. Therefore, it is a promising signal rather than an established protocol.

Read the full study:

https://www.sigmarepository.org/inrc/2026/posters_2026/60/

5. Integrating Clinical Information and Electrocardiographic Signal Features to Develop a Prediction Model for Postoperative Delirium in Older Patients: A Prospective Observational Study

PUBLICATION: International Journal of General Medicine

AUTHORS: Cheng Wu, Hanwen Fan, Liangju Lei, Wenbin Dai, Xiaoxia Duan, Wei Li

KEY FINDING:

In 767 patients aged 65 and older undergoing elective non-cardiac surgery, about 24 percent developed postoperative delirium. Adding electrocardiogram and heart rate variability features — notably higher fuzzy entropy, a measure of signal complexity and irregularity — to routine clinical data improved prediction, with discrimination of roughly 84 percent in the development group and about 78 percent in a separate testing group.

SIGNIFICANCE:

Signals already flowing from a routine electrocardiogram carry information about brain vulnerability that standard risk assessments miss, pointing toward nonlinear, complexity-based heart rate variability measures. This was a single-center observational study that needs external validation, and fuzzy entropy is not yet something a bedside monitor produces.

Read the full study:

https://www.dovepress.com/integrating-clinical-information-and-electrocardiographic-signal-featu-peer-reviewed-fulltext-article-IJGM

6. Psychological profile and heart rate variability in adults with self-perceived chronic stress: secondary analysis from a clinical trial

PUBLICATION: Frontiers in Physiology

AUTHORS: Ana Isabel Pérez Alcalde, María-José Giménez, Cecilia Estrada Barranco, Francisco J. Fernández-Rodríguez, Marta de la Plaza, María García-Arrabé, Beatriz Ruiz-Ruiz

KEY FINDING:

In 54 adults with self-perceived chronic stress, anxiety, depression, and psychological inflexibility were high, and heart rate variability was moderately reduced — but variability did not differ significantly across levels of perceived stress. Higher conscientiousness was modestly associated with several heart rate variability indices, and some differences between men and women appeared in the frequency-domain measures.

SIGNIFICANCE:

Felt stress and autonomic readout can come apart, so heart rate variability should not be used as a lie detector for how stressed someone truly is; combining it with psychological profiling flags risk better than either alone. This is a cross-sectional secondary analysis of a small, self-selected sample, so it is association, not causation.

Read the full study:

https://pmc.ncbi.nlm.nih.gov/articles/PMC13422212/

7. Long-term psychobiological stress responses following soft political repression

PUBLICATION: Scientific Reports

AUTHORS: Ruth Marheinecke, Laura Ramirez, Nils Opel, Carsten Spitzer, Bernhard Strauß, Veronika Engert

KEY FINDING:

Among 100 adults raised in East Germany (49 who experienced political repression and 51 matched comparisons), the repression group reported higher subjective stress but showed no significant differences in cortisol, heart rate, or heart rate variability during a laboratory stress test. Notably, those with the highest distress, anxiety, depression, and trauma symptoms more often declined to take part in the stress test.

SIGNIFICANCE:

Laboratory stress research in vulnerable populations may systematically screen out the people it most needs to understand, and a normal-looking physiological profile does not rule out deep suffering. This is an observational comparison of a modest, self-selected sample in which subjective and biological measures diverge.

Read the full study:

https://www.nature.com/articles/s41598-026-65049-8

KEY THEMES

SPONSORED BY OPTIMAL HRV

This episode is sponsored by Optimal HRV. Optimal HRV offers a structured morning measurement protocol, longitudinal tracking to help you see meaningful trends over time, and built-in biofeedback tools for practicing paced breathing and physiological regulation.

Learn More: www.optimalhrv.com

Medical disclaimer: This podcast is for informational and educational purposes only and does not constitute medical advice. Please consult your healthcare provider before making any changes based on this content.

In this episode of the Heart Rate Variability Podcast, Matt Bennett speaks with Zuzu Karen Arms about the deep connection between gut health, the autonomic nervous system, and heart rate variability.

Zuzu shares her personal journey of reversing epilepsy, scoliosis, and other health challenges through holistic approaches. The conversation explores how the gut microbiome supports nervous system regulation, why GABA production matters, and how gut health may influence conditions like POTS, dysautonomia, and low HRV.

Matt and Zuzu also discuss nutrition, fiber, probiotics, prebiotics, acupuncture, biofeedback, and the importance of creating the right internal environment for better autonomic balance.

Topics Covered

Key Takeaways

Gut health plays a major role in nervous system regulation, and the microbiome may directly influence HRV through mechanisms like GABA production, inflammation, and autonomic signaling.

Zuzu emphasizes that supporting the gut is not just about digestion. It can also affect energy, neurological function, emotional regulation, cardiovascular control, and resilience.

The discussion also challenges common nutrition assumptions, including the overemphasis on protein intake, while highlighting the importance of plant-based nutrients, fiber, and gut-friendly dietary patterns.

Medical disclaimer: This podcast is for informational and educational purposes only and does not constitute medical advice. Please consult your healthcare provider before making any changes based on this content.

Ethical Principles and Practice Standards in Clinical Biofeedback with Dr. Donald Moss — 3 APA CE credits, BCIA-aligned

https://www.optimalhrv.com/event-details-registration/master-ethical-principles-practice-standards-in-clinical-biofeedback-aligned-with-bcia

This Week in Heart Rate Variability. This is a milestone edition — our 50th episode in the This Week in HRV format, and the start of a more curated approach that organizes episodes around themes rather than publication timing. We begin that new chapter with performance, following the autonomic nervous system across five studies: from whether burnout leaves a measurable mark on the working heart, to the quiet self-talk that sharpens a golfer's focus, to hydrogen-rich water and faster recovery, to syncing breath with heartbeat at the edge of exhaustion, and finally to a blueprint for building biofeedback into how athletes train.

RESEARCH HIGHLIGHTS THIS WEEK

1. What Your Heart Reveals About Workplace Burnout

PUBLICATION: Frontiers in Physiology

AUTHORS: Irina Böckelmann, Jonas Hartung, Sabine Darius, Stefan Sammito, Beatrice Thielmann

KEY FINDING:

In 202 employees working in interaction-heavy jobs — nursery teachers, bank clerks, and medical assistants — only about 5 percent showed elevated burnout risk. Where heart rate variability differed by burnout risk, the differences showed up in the 24-hour and daytime recordings but not during sleep, and the correlations between HRV and burnout were mostly weak. Age and gender influenced HRV more than burnout status did.

SIGNIFICANCE:

This is a cross-sectional study, so it can show association but not causation — it cannot tell us that burnout changes HRV or the reverse. Still, the pattern hints that if HRV is going to reflect occupational strain, daytime and on-the-job recordings may be more sensitive than overnight data. For now, HRV looks like a possible complement to validated burnout questionnaires, not a standalone screening tool.

Read the full study:

https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2026.1908141/full

2. How Self-Talk Quietly Sharpens Focus Under Pressure

PUBLICATION: Behavioral Sciences

AUTHORS: Emmanouil Tzormpatzakis, Theodoros Proskinitopoulos, Orestis Panoulas, Evangelos Galanis, Evgenia Nikolakopoulou, Nikos Comoutos, Yannis Theodorakis, Antonis Hatzigeorgiadis

KEY FINDING:

Forty novice golfers were split into a control group and a group trained in strategic self-talk. The self-talk group improved their putting significantly more and outperformed the control group at the final assessment, while showing greater parasympathetic activation (in the root mean square of successive differences), especially toward the later stages of the task. The authors note the HRV pattern did not reach multivariate significance.

SIGNIFICANCE:

The physiological signal fits an attentional explanation: self-talk may help performers execute with less mental effort, keeping the rest-and-digest system more engaged under pressure. Strategic self-talk is a low-cost, teachable tool that appears to accelerate skill learning. The performance benefit is solid; the HRV mechanism is a promising hypothesis that still needs replication in larger, more diverse groups.

Read the full study:

https://www.mdpi.com/2076-328X/16/8/1347

3. The Water That May Help Athletes Bounce Back Faster

PUBLICATION: Journal of Sports Science and Medicine

AUTHORS: Zhihao Chen, Meilan Chi, Ruizhi Liu, Lianzhen Ma, Yupeng Shen

KEY FINDING:

In a randomized, single-blind, placebo-controlled crossover trial, 13 male university athletes did repeated sprint cycling once after drinking hydrogen-rich water and once after a placebo. The hydrogen-rich water trial produced significantly higher average power, less fatigue across sprints, faster post-exercise HRV recovery, and roughly 1 millimole per liter lower blood lactate three minutes after exercise. Each athlete served as their own control, which strengthens a small sample.

SIGNIFICANCE:

Faster HRV recovery is exactly what practitioners watch when judging how well an athlete's nervous system has absorbed a training load. If these acute effects hold up in larger, more diverse samples — including women and a range of competitive levels — hydrogen-rich water could become a meaningful recovery tool. For now it is a promising signal rather than an established recommendation, and commercial supplement products vary widely.

Read the full study:

https://www.jssm.org/jssm-25-744.xml-Fulltext

4. Syncing Your Breath to Your Heartbeat

PUBLICATION: Cureus

AUTHORS: Dai Kawakita

KEY FINDING:

In a preliminary case series of three healthy young men, each completed a graded cycling test with normal breathing and again with heart rate-synchronized breathing — a two-to-four inhale-to-exhale ratio cued to their own heartbeat. Two participants improved their anaerobic threshold and breathing efficiency with lower perceived exertion; the third got meaningfully worse. The split points to large individual differences in how people respond.

SIGNIFICANCE:

With only three participants, this is hypothesis-generating work, not proof in either direction. Its real value is the reminder that breathing interventions are not one-size-fits-all — the same protocol helped two people and hurt one. It strengthens the case for individualized assessment, potentially including each person's resonance frequency, before prescribing synchronized breathing.

Read the full study:

https://www.cureus.com/articles/483761-effects-of-heart-rate-synchronized-breathing-on-anaerobic-threshold-during-incremental-exercise-testing-a-preliminary-case-series

5. A Blueprint for Building Biofeedback Into Training

PUBLICATION: Biofeedback

AUTHORS: Iris Orbach, Boris Blumenstein, W. Alex Edmonds

KEY FINDING:

Rather than reporting new experimental data, this article reviews the current state of biofeedback training in sport and human performance and presents it as one part of a larger intervention package. The authors walk through training models — including a learning modification and periodization model illustrated with a sample case — for integrating biofeedback into an athlete's overall preparation. They close with recommendations for future research and applications beyond sport.

SIGNIFICANCE:

Individual studies show that specific tools can move specific markers, but practitioners need a structure for how to sequence and combine those tools across a season. This piece offers that connective tissue: a vocabulary and framework for periodizing biofeedback rather than bolting it on occasionally. As a literature review with an illustrative case, it is a roadmap to test, not evidence of superior outcomes.

Read the full study:

https://drive.google.com/file/d/1Lfc2I3ngKgRxV0koEb88QROIaRJYCKsn/view?usp=sharing

KEY THEMES

SPONSORED BY OPTIMAL HRV

This episode is sponsored by Optimal HRV. The Optimal HRV app offers a structured morning measurement protocol, longitudinal tracking to help you see meaningful trends over time, and built-in biofeedback tools for practicing paced breathing and physiological regulation.

Learn More: www.optimalhrv.com

Optimal HRV also offers professional training for clinicians:

Ethical Principles and Practice Standards in Clinical Biofeedback with Dr. Donald Moss — 3 APA CE credits, BCIA-aligned

https://www.optimalhrv.com/event-details-registration/master-ethical-principles-practice-standards-in-clinical-biofeedback-aligned-with-bcia

Medical disclaimer: This podcast is for informational and educational purposes only and does not constitute medical advice. Please consult your healthcare provider before making any changes based on this content.

Medical disclaimer: This podcast is for informational and educational purposes only and does not constitute medical advice. Please consult your healthcare provider before making any changes based on this content.

Ethical Principles and Practice Standards in Clinical Biofeedback with Dr. Donald Moss — 3 APA CE credits, BCIA-aligned

https://www.optimalhrv.com/event-details-registration/master-ethical-principles-practice-standards-in-clinical-biofeedback-aligned-with-bcia

This Week in Heart Rate Variability. In this episode, we trace the autonomic nervous system across an entire human lifespan — from a mother's anxiety reaching her baby's heart in the womb, to ADHD and the "vagal brake," to a middle school experiment on weight stigma and peer support, to how your menstrual cycle quietly reshapes your heart rhythm, all the way to AI models learning to forecast your next heartbeat.

RESEARCH HIGHLIGHTS THIS WEEK

1. Does Mom's Anxiety Change Baby's Heartbeat? It Depends on Baby's Sex

PUBLICATION: Journal of Affective Disorders

AUTHORS: Anna M. Zhou, Sarah E. Maylott, Nicolette C. Molina, Dylan Neff, Elisabeth Conradt, Sheila E. Crowell

KEY FINDING:

In 159 mother-fetus pairs, higher maternal anxiety was linked to elevated fetal heart rate specifically in male fetuses, not female ones. Broader maternal depression and anxiety symptoms were tied to lower fetal heart rate variability regardless of fetal sex.

SIGNIFICANCE:

This suggests prenatal maternal mental health shapes fetal autonomic development in sex-specific ways, reinforcing why prenatal mental health screening matters for the baby, not just the mother.

Read the full  study:

https://www.sciencedirect.com/science/article/abs/pii/S0165032726011833

2. What Your Heart Rate Reveals About ADHD (And What It Doesn't)

PUBLICATION: Middle East Current Psychiatry

AUTHORS: Davoud Amiri, Lamberto Briziarelli, Swetang J. Shah, Sara Amiri, Hadi Rahimi-Danesh

KEY FINDING:

This clinical review found that reduced heart rate variability in ADHD shows up most consistently under cognitive or emotional stress, not at rest, with wide variation driven by age, medication status, and coexisting anxiety.

SIGNIFICANCE:

The authors propose a "phenotype-informed" framework linking autonomic profiles to emotional dysregulation and medication tolerability — a promising but still hypothesis-generating direction, not a diagnostic tool.

Read the full study:

https://link.springer.com/article/10.1186/s43045-026-00658-7

3. The Middle School Study That Shows Why Peer Support Protects the Heart

PUBLICATION: Adolescents

AUTHORS: Meghan J. Gangel, Daniel Hamill, Alleyne P. R. Broomell

KEY FINDING:

In 31 middle schoolers, internalized weight stigma alone didn't predict stress reactivity — but among adolescents with low peer acceptance, higher weight stigma triggered a significantly larger sympathetic stress response. High peer acceptance eliminated that effect entirely.

SIGNIFICANCE:

Peer belonging may physiologically buffer adolescents from the harms of internalized weight stigma, suggesting interventions should target social acceptance, not just body-image beliefs, on their own.

Read the full study:

https://www.mdpi.com/2673-7051/6/4/56/pdf?version=1784900255

4. Your Cycle Is Quietly Reshaping Your Heart Rate Variability

PUBLICATION: Cureus

AUTHORS: Krity Singh, Vishavdeep Kaur, Ankalayya Bobbara

KEY FINDING:

Tracking 50 healthy women across the menstrual cycle, researchers found HRV peaked during the estrogen-dominant proliferative and ovulatory phases and dropped during menstruation and the secretory phase.

SIGNIFICANCE:

Menstrual phase should be treated as a standard variable in HRV research and personal tracking — ignoring it risks mistaking a normal hormonal shift for stress, poor recovery, or overtraining.

Read the full study:

https://www.cureus.com/articles/490447-phase-dependent-changes-in-heart-rate-variability-during-the-menstrual-cycle-in-healthy-young-women-at-a-tertiary-care-center?score_article=true#!/

5. Can Heart Rate Variability Predict Brain Complications After Hemorrhage?

PUBLICATION: Bioengineering

AUTHORS: Valerie C. Schütz, Jens M. Boss, Corinne Inauen, Stefan Y. Bögli, Tilman Beck, Emanuela Keller, Jan F. Willms

KEY FINDING:

In 101 patients with brain hemorrhage, a machine learning model combining HRV with clinical and lab data predicted delayed cerebral ischemia (which occurred in 34.7% of patients) with an AUC of 0.68 — and HRV features drove over half the model's predictive power.

SIGNIFICANCE:

HRV may offer an early, non-invasive warning signal for a dangerous complication, though the authors call for external validation before any bedside use.

Read the full study:

https://www.mdpi.com/2306-5354/13/8/857

6. AI Models Are Learning to Forecast Your Heart Rate Variability

PUBLICATION: arXiv preprint accepted, Computing in Cardiology

AUTHORS: Luukas Peräkylä, Fahad Sohrab, Ville Hautamäki, Merja Heinäniemi, Sui Huang, Pekka Abrahamsson

KEY FINDING:

Using data from 49 healthy individuals wearing consumer devices, pretrained AI "time series foundation models" outperformed traditional statistical methods at forecasting short-term HRV up to two hours ahead — without any task-specific training.

SIGNIFICANCE:

This early benchmark hints at a future where wearables forecast your nervous system's trajectory instead of just reporting yesterday's numbers, though it remains a feasibility study, not a validated tool.

Read the full study:

https://arxiv.org/pdf/2607.20027

KEY THEMES

SPONSORED BY OPTIMAL HRV

This episode is sponsored by Optimal HRV. The Optimal HRV app offers a structured morning measurement protocol, longitudinal tracking to help you see meaningful trends over time, and built-in biofeedback tools for practicing paced breathing and physiological regulation.

Learn More: www.optimalhrv.com

Optimal HRV also offers professional training for clinicians:

Ethical Principles and Practice Standards in Clinical Biofeedback with Dr. Donald Moss — 3 APA CE credits, BCIA-aligned

https://www.optimalhrv.com/event-details-registration/master-ethical-principles-practice-standards-in-clinical-biofeedback-aligned-with-bcia

Medical disclaimer: This podcast is for informational and educational purposes only and does not constitute medical advice. Please consult your healthcare provider before making any changes based on this content.

In this episode of the Heart Rate Variability Podcast, Matt Bennett speaks with Dr. Diana Driscoll about her work in autonomic health, POTS, inflammation, and recovery from complex chronic illness.

Dr. Driscoll shares her journey from optometrist to patient-researcher after developing POTS following a viral illness. When traditional medical care failed to help her and her family, she began investigating the underlying causes of autonomic dysfunction.

She explains why she views POTS not as a single disease, but as a presentation of deeper issues involving inflammation, neurotransmitter disruption, cardiovascular problems, intracranial pressure, and genetic predispositions. The conversation also explores her development of Parasym Plus and her recovery-focused approach to treatment.

Matt and Dr. Driscoll discuss how HRV can be used to track autonomic function and recovery over time, as well as the importance of persistence, proactive care, and continuing to search for answers.

Key Takeaway

Dr. Driscoll offers a recovery-focused view of POTS and autonomic dysfunction, emphasizing the importance of identifying and treating the underlying causes rather than only managing symptoms.