What the research shows, and how a ten-week protocol is structured.
Most people expect a concussion to resolve in two weeks. For a meaningful minority of executives, athletes, and performers, it does not. Headaches persist. Screens become intolerable. Sleep fragments. Concentration that used to be automatic now takes visible effort, and the emotional volatility is often the part that frightens people most. When imaging is clean and the neurological exam is unremarkable, patients are frequently told to wait. Waiting is not a protocol.
A growing body of research points somewhere more useful: much of what we call persistent post-concussion symptoms is driven by a dysregulated autonomic nervous system, and the autonomic nervous system is trainable.
The brain regulates the heart continuously through the vagus nerve and the sympathetic branches, and injury disrupts that regulation. Reviews of the pathophysiology describe reduced parasympathetic activity, blunted baroreflex function, and exercise intolerance after mild traumatic brain injury, with symptoms including dizziness, headache, fatigue, and poor tolerance of cognitive load (Esterov and Greenwald, 2017, Brain Sciences; Purkayastha, Stokes, and Bell, 2019, Brain Injury).
Heart rate variability, the beat-to-beat variation in heart rhythm, is the cleanest non-invasive index of that regulation. A systematic review of the relationship between traumatic brain injury and HRV found consistent disruption of HRV after injury across the literature (Talbert and colleagues, 2024, Applied Psychophysiology and Biofeedback). In a prospective study of 19 concussed and 19 uninjured athletes, investigators found that Mayer wave activity near 0.1 Hz, the baroreflex-driven blood pressure rhythm, was significantly reduced within 48 hours of sport concussion, with the difference resolving by one week in that sample (La Fountaine and colleagues, 2022, Annals of the New York Academy of Sciences). The 0.1 Hz band is the same frequency that resonance breathing engages.
That convergence matters. The frequency at which the cardiovascular system is most disturbed after concussion is the frequency HRV biofeedback trains.
HRV biofeedback is not generic deep breathing and it is not a relaxation app. The patient breathes at their individually determined resonance frequency, typically between 4.5 and 6.5 breaths per minute, while watching their own heart rhythm on screen. At that rate, respiration, heart rate, and blood pressure oscillations phase-lock, the baroreflex is repeatedly stretched and loaded, and HRV amplitude rises dramatically within a single session.
The purpose is not the calm feeling during the session. The purpose is the training effect: repeated loading of the baroreflex over weeks appears to increase the gain of the system, so autonomic recovery after stress becomes faster outside of practice. In clinical work with executives, athletes, and performers, this is the distinction that matters most. We are not teaching people to relax on cue. We are rebuilding the speed at which their physiology returns to baseline after a demand.
Protocols in the published literature vary widely, which is a real limitation of the field. A systematic review of HRV biofeedback after traumatic brain injury found that participants completed an average of 11 sessions, and protocols differed substantially across studies (Talbert and colleagues, 2023, Brain Injury). In my own practice the protocol runs 10 weeks: resonance frequency assessment first, then daily paced breathing practice, progressive shifts in the target from amplitude to control, and structured exposure to the stressors that actually provoke symptoms.
The honest summary is that the evidence is promising, heterogeneous, and still maturing.
The 2023 systematic review examined seven eligible studies and reported that HRV biofeedback was associated with improved HRV after traumatic brain injury, along with improvements in cognitive and emotional functioning and in physical symptoms including headaches, dizziness, and sleep problems. The same review was explicit about the caveats: study quality was poor to fair, and because every included study reported positive results, publication bias is likely (Talbert and colleagues, 2023, Brain Injury).
A randomized controlled study in mild traumatic brain injury compared HRV biofeedback training with a psychoeducation control condition in patients recruited from two university hospitals in Taipei. Forty-one of forty-nine participants completed the study, and the design used performance-based neuropsychological measures alongside symptom checklists and anxiety and depression inventories rather than relying on self-report alone. Executive function, information processing, verbal memory, emotional functioning, and HRV improved significantly in the biofeedback group, while the psychoeducation group showed no change (Lu, Gevirtz, Yang, and Hauson, 2023, Applied Psychophysiology and Biofeedback).
The most methodologically demanding entry is recent, and its results are instructive precisely because they are mixed. A randomized sham-controlled trial enrolled fifty-eight participants with traumatic brain injury (forty-nine completed) for five weekly sessions. The biofeedback group showed a higher LF/HF ratio at rest and during recovery from a stressor, a pattern the authors interpret as possible baroreflex engagement, and a greater improvement in depression. Other HRV differences disappeared after adjusting for baseline values, and cognitive and emotional gains appeared in both the biofeedback and sham groups (Talbert and colleagues, 2025, Applied Psychophysiology and Biofeedback). Sham-controlled designs are the right next step for this field, because expectancy effects are substantial in any intervention that involves attention to the body, and five sessions is a short dose.
In severe traumatic brain injury, a randomized controlled trial allocated fifty adults to six sessions of resonance frequency biofeedback or a waitlist. Biofeedback did not change responses to a laboratory anger-induction task, but it did produce fewer sleep disturbances and reduced negative mood and depression at follow-up (Wearne and colleagues, 2021, Brain Injury).
Breathing work in sport concussion is also being examined directly. A randomized crossover trial in twenty-six male rugby athletes with persistent post-concussive symptoms compared resonance breathing with a pelvic floor resonance breathing variant across a three-week, one-week washout, three-week design. Total symptom scores fell after both interventions, heart rate was lower and HRV total power higher after both, and the two approaches produced different EEG and sympathetic nerve activity patterns, with emotional symptoms responding more to resonance breathing and somatic symptoms to the pelvic floor variant (Wang and colleagues, 2026, Frontiers in Neuroscience).
Recruitment is also underway for a Department of Defense supported randomized controlled trial at Virginia Commonwealth University testing HRV biofeedback for persistent post-concussion symptoms in veterans, service members, and civilians, with completion projected for 2028 (ClinicalTrials.gov, NCT07071350). That trial is the one to watch, because sample size and control conditions are where this literature is currently thin.
Three practical conclusions follow from the evidence as it stands.
First, if your symptoms persist beyond the expected recovery window and include dizziness, exercise intolerance, poor stress tolerance, or fragmented sleep, an autonomic assessment is reasonable. Disrupted HRV after injury is well documented, and it is measurable in an office visit. If you already track HRV on a wearable, that data is a useful starting point: the wearable tells you where your autonomic system is, and training is what moves it.
Second, expect a training protocol, not a treatment you receive passively. The dose in the literature is roughly ten sessions plus daily home practice. Adherence is the variable most likely to determine your result, and it was explicitly examined in the 2025 sham-controlled trial for that reason.
Third, be appropriately skeptical of any claim that this is proven. It is not proven. It is plausible on mechanism, consistently positive in small studies, and now entering the phase of sham-controlled and adequately powered trials. For a non-invasive intervention with minimal downside in a population with few alternatives, that risk-benefit profile is favorable, but the language should stay honest.
Post-concussion recovery frustrates high performers because effort does not help and rest does not finish the job. Training the autonomic system gives the patient something specific to do, and a physiological signal to watch while they do it.
Esterov, D., and Greenwald, B. D. (2017). Autonomic Dysfunction after Mild Traumatic Brain Injury. Brain Sciences, 7(8), 100. PMID 28800081.
La Fountaine, M. F., Hohn, A. N., Leahy, C. L., Testa, A. J., and Weir, J. P. (2022). Use of Mayer wave activity to demonstrate aberrant cardiovascular autonomic control following sports concussion injury. Annals of the New York Academy of Sciences, 1507(1), 121-132. PMID 34480369.
Lu, H. C., Gevirtz, R., Yang, C. C., and Hauson, A. O. (2023). Heart Rate Variability Biofeedback for Mild Traumatic Brain Injury: A Randomized-Controlled Study. Applied Psychophysiology and Biofeedback, 48(4), 405-421. PMID 37335413.
Purkayastha, S., Stokes, M., and Bell, K. R. (2019). Autonomic nervous system dysfunction in mild traumatic brain injury: a review of related pathophysiology and symptoms. Brain Injury, 33(9), 1129-1136. PMID 31216903.
Talbert, L. D., Kaelberer, Z., Gleave, E., Driggs, A., Driggs, A. S., Steffen, P. R., Baldwin, S. A., and Larson, M. J. (2023). A systematic review of heart rate variability (HRV) biofeedback treatment following traumatic brain injury (TBI). Brain Injury, 37(7), 635-642. PMID 37138494.
Talbert, L. D., Kaelberer, Z., Gleave, E., Driggs, A., Driggs, A. S., Baldwin, S. A., Steffen, P. R., and Larson, M. J. (2024). A Systematic Review of the Relationship Between Traumatic Brain Injury and Disruptions in Heart Rate Variability. Applied Psychophysiology and Biofeedback, 49(4), 523-540. PMID 39222209.
Talbert, L., Allen, W., Wheeler, A., Hartwell, B., Jensen, T., Young, E., Baldwin, T., Olpin, K., Baldwin, S., Hopkins, R., Steffen, P., Thayer, J., and Larson, M. (2025). A Randomized Sham-Controlled Trial of Heart Rate Variability Biofeedback Following Traumatic Brain Injury (TBI). Applied Psychophysiology and Biofeedback, 51(2), 327-348 (print 2026, online 2025). PMID 40828260.
Wang, W., Zhu, H., Gao, X., Yu, T., Yan, X., Wang, G., and Zhang, Z. (2026). Respiratory modulation of neurophysiology and symptoms in athletes with sports-related concussion: a randomized crossover trial. Frontiers in Neuroscience, 20, 1825070. PMID 42388669.
Wearne, T. A., Logan, J. A., Trimmer, E. M., Wilson, E., Filipcikova, M., Kornfeld, E., Rushby, J. A., and McDonald, S. (2021). Regulating emotion following severe traumatic brain injury: a randomized controlled trial of heart-rate variability biofeedback training. Brain Injury, 35(11), 1390-1401. PMID 34487459.
Virginia Commonwealth University and U.S. Department of Defense. Randomized Controlled Trial of Treatment to Optimize Heart Rate Variability for Persistent Post-Concussion Symptoms. ClinicalTrials.gov identifier NCT07071350, recruiting, completion projected September 2028.
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