HRV and Concussions: A New Frontier in Sports Medicine

This new emerging research with novel insights investigates heart rate variability (HRV) as a potential biomarker for monitoring recovery after sports-related concussions. Mild traumatic brain injury (mTBI) remains a significant public health concern, particularly in athletics, where concussions are common but often underreported or underestimated. Current assessments—such as cognitive tests or symptom checklists—struggle to capture the hidden autonomic disturbances that persist long after overt symptoms fade.

Biofeedback and neurofeedback offer a window into otherwise unconscious physiological processes, empowering individuals to regulate them in real-time. In this context, HRV is particularly compelling: it reflects the delicate interplay between the sympathetic and parasympathetic nervous systems and serves as a non-invasive index of autonomic flexibility. By exploring HRV changes after concussion, researchers aim to uncover an easy to use, on-field and more reliable tool for tracking recovery and guiding return-to-play decisions.

Methods

The study recruited 23 athletes (16 concussed, 7 healthy controls) from youth, high school, and collegiate sports programs. Participants underwent both psychological and physiological assessments:

• Self-report tools:

  • Impact of Events Scale–Revised (IES-R) to measure distress.

  • Sport Concussion Assessment Tool, Fifth Edition (SCAT-5) for post-concussion symptoms.

• Physiological measures:

  • A 10-minute baseline HRV assessment, focusing on key indices:

    • RMSSD (root mean square of successive differences),

    • SDNN (standard deviation of normal-to-normal intervals),

    • lnHF (log-transformed high-frequency power, reflecting vagal tone).

• Procedures:
  Athletes’ HRV was recorded under controlled resting conditions. Statistical analyses compared concussed vs. control groups, and regressions examined HRV relative to time since injury.

Unlike standard concussion assessments that can be influenced by underreporting or “sandbagging” baseline tests, HRV measures provide direct insights into autonomic nervous system functioning. This methodological approach highlights the value of integrating psychophysiological measures into concussion care.

Results

The findings showed clear physiological distinctions:

• Lower HRV in concussed athletes: RMSSD, SDNN, and lnHF were all significantly reduced in the mTBI group compared to controls.

• Time-sensitive recovery patterns: Within the concussed group, HRV values demonstrated a linear improvement relative to days since injury.

• Mismatch with self-reports: No significant differences were found in self-reported distress or symptom severity over time, suggesting that subjective measures may fail to capture ongoing physiological dysfunction.

These results underscore HRV’s potential as an objective, quantifiable marker of recovery that complements, rather than replaces, existing tools.

Discussion

The implications of this research reach far beyond laboratory findings. For athletes, recovery from concussion is not just about the absence of headaches or dizziness but about the brain and body regaining autonomic balance. Persistent dysregulation of the ANS—even after symptoms fade—may predispose athletes to reinjury if they return to play too soon. By leveraging HRV, clinicians can better time interventions, personalize recovery, and reduce long-term risks.

• Clinical practice: HRV monitoring could be integrated into sports medicine protocols as a routine measure, much like blood pressure checks. It provides a non-invasive, repeatable metric of underlying autonomic function.

• Therapeutic relevance: Biofeedback interventions targeting HRV (such as resonance frequency breathing) are already shown to enhance autonomic regulation. Combining these with concussion protocols could accelerate recovery.

• Research perspective: Future work should expand sample sizes, investigate long-term effects, and integrate HRV into multi-modal assessment batteries that include EEG-neurofeedback, cognitive testing, and emotional profiling.

Underlying all of this is a shift: from viewing concussion as a purely cognitive or symptomatic problem, to recognizing it as a systemic psychophysiological event with measurable biomarkers.

Brendan’s Perspective

In clinical neurofeedback practice, I often see clients—especially athletes—who present with subtle but persistent changes after concussion. Their qEEG profiles sometimes look relatively stable, yet their physiology tells another story. HRV bridges this gap beautifully: it reminds us that the heart and brain are in constant conversation, and that disruption in one inevitably echoes in the other.

From a protocol standpoint, I regularly integrate HRV biofeedback alongside EEG-neurofeedback in post-concussion care. A fairly standard (but individualised) course of training can look like:

• HRV coherence biofeedback to restore parasympathetic flexibility.

• Inhibiting excessive theta (often temporal or prefrontal) to address lingering post-conscussive symptoms. 

• SMR training at C3/C4 for cortical regulation, motor stability and inhibition.

• Posterior alpha training for emotional regulation and reestablishing the DMN. 

The synergy here is powerful. While EEG helps restore cortical regulation, HRV biofeedback recalibrates the autonomic system. Together, they mutually and reciprocally support resilience and self-regulation at multiple levels.

I also want to highlight the importance of individualization. Not all concussions are alike. Some athletes may present with anxiety and hyperarousal, requiring calming protocols (e.g., enhancing alpha power at Pz or increasing vagal tone via HRV training). Others may exhibit fatigue and hypoarousal, calling for beta training or stimulating coherence exercises. Over compensators often need to down-train high-beta. This variability reflects what the study underscores: recovery is nonlinear and deeply personal.

Finally, we must be cautious in interpreting research that relies solely on symptom resolution. The “I feel fine, coach” narrative is one of the most dangerous in sports medicine. Objective tools like HRV help us challenge that narrative with data—and, more importantly, with compassion. Our role as practitioners is to listen not only to what the athlete says but also to what their nervous system whispers.

Conclusion

This study highlights HRV’s promise as a biomarker for concussion recovery. While conventional assessments focus on symptoms, HRV captures the hidden dynamics of autonomic regulation, offering clinicians and athletes a clearer map of the recovery journey. Incorporating HRV into return-to-play guidelines could reduce reinjury risk, individualize care, and open the door for combined HRV–neurofeedback interventions that support whole-person healing.

The take-home message: recovery is more than feeling ready—it’s about being physiologically ready. HRV gives us the tools to know the difference.

Reference

Cintas, J. L. (2025). Heart rate variability as a biomarker for sport-related concussions: Implications for future return to play guidelines (Doctoral dissertation, California School of Professional Psychology, Alliant International University, San Diego).