Heart Rate Variability & Concussions

Through news articles, special reports, blockbuster movies, and even the involvement of the US Congress, we now know that there is irreversible physical and psychological damage caused by concussions.  Primarily, the focus of concussions, or mild traumatic brain injuries (MTBI), has been in relation to athletes. However, only about 20% of traumatic brain injuries occur in a sports setting, meaning that far more head injuries occur outside of athletic activities. Many people suffer the same concussion symptoms as we have heard from famous athletes, including cognition/concentration issues, sensitivity to light, headaches, poor sleep, anxiety and severe depression.

How concussions are viewed and treated has evolved over time. “Just rest” advice from doctors use to be the common way to handle MTBIs. But now hundreds of protocols and assessment tools are available to determine the severity of a MTBI and decide when someone is clinically back to an asymptomatic condition or “normal”. One major disadvantage of these tools is that many of them are subjective, leaving a patient’s recovery based on their feelings and not physiology.

In an effort to improve MTBI management, many sports organizations and certain job types now perform pre-season or pre-job baseline assessments used for comparison in the event a person receives a concussion. Again, unfortunately, most of these baseline assessments are subjective, allowing people to manipulate the results. It is known that some athletes have purposely performed poorly on their initial “baseline” concussion tests so that in the event they did sustain a concussion it would not register when compared to their baseline allowing them to more likely be able to return to play sooner. This is one example demonstrating the need for a combination of credible subjective and objective measurement tools.

Heart Rate Variability is an example of an objective tool that can be used along with subjective measurements to help determine a person’s status in the healing process. It can help remove bias to ensure athletes or other people who sustain a MTBI are physiologically ready to return to their respective activities. So how is HRV correlated to MTBIs?

HRV is an objective tool that can help determine a person’s status in the healing process and people who sustain a concussion are physiologically ready to return to their respective activities.

Research has shown that neuropathological changes may occur when a concussion is experienced. Symptoms from MTBIs are believed to reflect functional disturbance of the central nervous system, which would cause dysfunction in the autonomic nervous system (ANS).  The literature suggests that a MTBI can modify cardiac autonomic cadence, i.e., the variability of the heartbeat, to become more consistent, especially in response to ANS stimulation by such things as exercise. Since Heart Rate Variability is a non-invasive measure of the ANS, HRV analysis can therefore be used to determine if the MTBI is affecting ANS function. HRV measurements can be done daily and easily to help guide concussion treatment and assure the treatment is promoting proper recovery in conjunction with other assessments and protocols.

Since Heart Rate Variability is a non-invasive measure of the Autonomic Nervous System (ANS) , HRV analysis can therefore be used to determine if the mild traumatic brain Injury (MTBI) is affecting ANS function.

Ideally, HRV would be used as a metric in the initial “baseline” concussion tests and in any subsequent concussion tests because it provides a physiological biomarker that better distinguishes the healing status and cannot easily be manipulated. HRV (and ANS function and balance) has even proven to be affected by MTBIs even after most the common concussion symptoms are past and most patients are “cleared” to resume activities by other concussion management protocols. Since HRV can pick up on the subtle nervous system imbalances that might not be obvious through symptoms or subjective measurement, this makes it very powerful in ensuring that someone that has sustained a concussion is not prematurely cleared. HRV can still be useful in guiding MTBI treatment even if you have no HRV baseline values.

HRV (and ANS function and balance) has even proven to be affected by MTBIs even after most the common concussion symptoms are past and most patients are “cleared” to resume activities by other concussion management protocols.

If you or your client is suffering symptoms from a concussion/MTBI, here are some things to focus on and ways to use HRV to guide treatment:

1. Optimize nutrition

A proper nutrition plan will allow for increased energy to promote tissue repair, regulate inflammation and provide essential micronutrients needed for proper nervous system function.  A focus on high quality, whole foods supported by proper supplementation if needed can cause a significant increase in function and decrease in MTBI symptoms. What to focus on:

• Consume enough calories – It’s important to get enough calories to support the increased nutrient needs that may accompany a concussion/MTBI.
• Focus on anti-inflammatory foods – High levels of inflammation is associated with poorer outcomes after head injury.
• Increase intake/supplement with Omega-3 fatty acids – They counteract free radicals that cause oxidative damage to brain cells and may help improve nerve signal transmission at synapses.

2. Getting back to physical activity

Exercise intensity and load need to be regulated as people can become symptomatic with side effects from their MTBI.  However, HRV can be used to determine daily readiness to participate in exercise.  Even though there is not much research on this topic, here are some ways others have found HRV useful with concussion management:

• Look at the morning readiness the day after exercise – doing this along with subjective measurements like sleep quality and MTBI symptoms, to determine how it affects your ANS.
• Take pre and post workout readings to determine how much stress you accumulated –   Track this with morning readings to determine the right amount of intensity for your workouts.
• Monitor your HRV for 10 minutes at a maintained intensity, you can track your values to determine your progress in recovery – One study demonstrated that those who were experiencing symptoms from an MTBI have decreased HRV values during the 10-minute exercise and showed decreased symptoms when their HRV started to increase during these exercise bouts.

These are only some of the ways I have used HRV with my MTBI clients and should be used in conjunction with other tests to help to determine when a patient should be clinically cleared of their MTBI.

3. Use HRV Biofeedback training

A few studies have shown that performing HRV Biofeedback training will help improve mood and aid in rehabilitation from a MTBI.  HRV Biofeedback training is a live process where you manipulate HRV in real-time through mindfulness, meditation or methods to improve a mental state.  By doing this training, you can gain better control of your ANS to help restore the proper autonomic balance. Here are a few ways to use HRV Biofeedback:

• Achieve a state of coherence – The term coherence typically refers to combining a positive mindset with certain breathing patterns. In theory, it aligns your ANS for both performance and recovery.
• Use various meditation techniques – there are many forms of meditation techniques so try out several and monitor your HRV to see which style works best for you.
  

In summary, there are some great advantages to using HRV in the management and treatment of MTBIs in conjunction with other assessments and tools.  There is a vast amount of money being applied to concussion research and safety and Heart Rate Variability can provide an inexpensive, objective tool to aid in the advancement of different treatments and assure meaningful physiological and emotional changes are happening for those suffering from concussion symptoms.

If you want to know more about HRV, how it works or ways to improve your values, access the “Foundations of Heart Rate Variability” course and learn more about how to accurately measure and analyze HRV.

References:

Abaji, J. P., Curnier, D., Moore, R. D., & Ellemberg, D. (2016). Persisting Effects of Concussion on Heart Rate Variability during Physical Exertion. Journal of Neurotrauma, 33(9), 811-817. doi:10.1089/neu.2015.3989

Average, E. (n.d.). Get the Stats on Traumatic Brain Injury in the United States. Retrieved from https://www.cdc.gov/traumaticbraininjury/get_the_facts.html

https://www.cdc.gov/traumaticbraininjury/data/index.html

Conder, R. L., & Conder, A. A. (2014). Heart rate variability interventions for concussion and rehabilitation. Frontiers in Psychology Front. Psychol., 5. doi:10.3389/fpsyg.2014.00890

Fountaine, M. F., Toda, M., Testa, A. J., & Hill-Lombardi, V. (2016). Autonomic Nervous System Responses to Concussion: Arterial Pulse Contour Analysis. Frontiers in Neurology Front. Neurol., 7. doi:10.3389/fneur.2016.00013

Gall, B., Parkhouse, W., & Goodman, D. (2004). Heart Rate Variability of Recently Concussed Athletes at Rest and Exercise. Medicine & Science in Sports & Exercise, 36(8), 1269-1274. doi:10.1249/01.mss.0000135787.73757.4d

Jay, G. 2000. Minor Traumatic Brain Injury Handbook: Diagnosis and Treatment. New York: CRC Press.

Johnson, V. E., Stewart, W., & Smith, D. H. (2013). Axonal pathology in traumatic brain injury.Experimental Neurology, 246, 35-43. doi:10.1016/j.expneurol.2012.01.013

Nemechek, P. (2016, January 1). Sports-related brain injury and autonomic nervous system. Retrieved from https://www.autonomicrecovery.com

Senthinathan, A., Mainwaring, L. M., & Hutchison, M. (2016). Heart Rate Variability of Athletes Across Concussion Recovery Milestones. Clinical Journal of Sport Medicine, 1. doi:10.1097/jsm.0000000000000337