Apr 17 / Jacko

Improve Brain Injury & Concussion Recovery With Breath Training

Post-concussion or traumatic brain injury (TBI) pathophysiological changes and alterations in brain function occur which influence our breathing. Increased breathing rate, altered breathing mechanics and reduced end tidal carbon dioxide (CO2) have all been noted in the literature around brain injuries and breathing (Churchill, 2017).

The most common traits of dysfunctional breathing have been identified as altered mechanics, faster breathing and an increased sensitivity to carbon dioxide (indicated by lower end tidal CO2 levels). Even with patients not suffering from acute stress of brain injuries but instead periods of emotional stress have been precursors for dysfunctional breathing. With brain injuries we also have the emotional stress from the injury and altered cognitive function as well as the physical impact of the stress.

The development of dysfunctional breathing identified as unconsciously learned habitual change from the normal pattern of breathing, which may begin as a “coping mechanism” to deal with any periods of stress. As it’s unconscious you might not even realise or notice anything has changed. I went for 4 to 5 years before realising my breathing was an issue after my brain injury. Our breathing is unlikely to normalise itself after a brain injury, hence why we need to ‘re-train’ and recalibrate our breathing patterns and sensitivity to CO2.

What is the dysfunctional breathing we’re likely to see post-concussion or brain injury?

The altered breathing mechanics are identified with the flattening or the diaphragm, which becomes less mobile; thus, the accessory and intercostal muscles contribute more to movement required for breathing (Watson et al, 2021). This looks like more vertical upper chest movement. It makes the breathing less efficient and fatiguing of these muscles explains some of the symptoms these patients experience: headaches from tight neck muscles, chest pain and dyspnoea. Additionally, these changes are associated with changes in the patterning of breaths; patients exhibit erratic rates and volumes of respiration with rapid shallow breaths or periodic deep sighing breaths. An increase in respiration rate may be observed, sometimes resulting in measurable hypocapnia (Barker, 2015). 

How breath-holding and CO2 tolerance key to improve cerebral blood flow

In the first blog on ‘Concussions & Breathing’ 60 years of research pointed towards the key determining factor of improving brain recovery and cognitive function was cerebral blood flow (CBF). Reduced CBF as a result of both the inflammatory response from the brain due to the impact of the injury but also the reduction in end tidal CO2 reported. Reduced end tidal CO2 means an increase in sensitivity to CO2 and therefore reduction in atrial CO2 levels reducing blood flow as CO2 is a vasodilator.

One very simple and safe, yet effective way to improve CO2 tolerance and atrial CO2 is through breath-holding. During breath-holding, the increase in CO2 gives rise to increased CBF because of vasomotor reactivity. Numerous studies in humans and animals involving the use of many different techniques have shown consistent results of cerebral vasodilatation to hypercapnia (high levels of CO2) and vasoconstriction to hypocapnia (low levels of CO2) which has been known since as far back at the 1940’s (Kety, 1948).

A study in the American Journal of Neuroradiology showed that both a 40 second breath-hold after an inhale and a 30 second breath-hold after a normal exhale improve CBF, with the shorter 30 second hold, but after an exhale, improved CBF to a greater degree, an average increase from between 47% and 87% (Kastrupt et al, 1999).

Understanding that cerebral blood flow is directly affected by carbon dioxide levels in the blood, which is related to our brains chemosensitivity to carbon dioxide as our primary breathing stimulus. We know brain injuries alter our end tidal carbon dioxide when assessing breathing post injury indicating an increase in carbon dioxide sensitivity and reduced cerebral blood flow. Knowing that improving cerebral blood flow is the key mechanism to help the brain recovery the simple act of breath-holding can both improve CBF but also help restore the brain chemosensitivity to carbon dioxide.

Simply holding the breath for just 30 seconds could help increase CBF by 87% but is this appropriate for someone post brain injury or concussion? Understanding how to simply assess breathing post injury and what type of breathing exercises including breath-holding are appropriate depending on the breathing assessments is covered in the final section of this blog.

Brain injury effect on nervous system

A study from the Brain Injury journal in 2017 cited that within the initial 72 hours post brain injury there was a measurement of autonomic nervous system dysfunction. During the acute phase of a brain injury this is not surprising as we know breathing patterns and sensitivity are affected and know that breathing as an autonomic function within the body is linked in with the autonomic nervous system. If breathing is negatively affected we can expect to observe dysfunction in the autonomic nervous system. We see an increase in sympathetic tone as part of the fight or flight stress response to the injury and an increase in brain inflammatory markers. How we breathe post injury can either keep us in that state of sympathetic activation or can help us recovery out of it.

Further more, another study from 2017 this time in the Clinical Journal of Sport Medicine stated that athletes with concussion displayed autonomic dysfunction in some measures of Heart Rate Variability (HRV) that persisted beyond ‘Return to Play’ (RTP) protocols and were related to a previous history of concussion (Senthinathan, 2017). Showing once again that the brain and nervous system have not fully healed even once common symptoms have reduced. This is extremely important for protecting players in contact sports for going back into the sport and also gives a non-evasive way to assess nervous system recovery and potentially the brain’s recovery.

HRV can be measured simply with some relatively low cost technology. There are devices available now that measure real time HRV and give biofeedback via an App on your phone using a polar 10 heart rate monitor, making it very easy to assess, monitor and track HRV.

How we breathe is not only going to have a direct impact on CBF but also the functioning of our whole autonomic nervous system. Breathing is affected by brain injuries and concussion, however it’s also our ‘tool’ to help recovery the brain and restore the autonomic nervous system.

Why nasal breathing a must for brain function

There is evidence that nasal breathing affects the central nervous system (CNS) differently than mouth breathing. While nasal breathing synchronizes electrical activity in the olfactory cortex as well as amygdala and hippocampus, mouth breathing does not, which has implications for stress management and treatment of anxiety.

Consciously ensuring nasal breathing during any daily tasks and making nasal breathing a normal habit is a key first step in recalibrating our relationship with breathing. It’s common that one of the dysfunctional breathing trait you’ll see or experience post brain injury is more mouth breathing. Not only does it affect the nervous system differently than nasal breathing but it’s also linked to faster breathing rates and lower end tidal carbon dioxide. So by restoring nasal breathing post brain injury or concussion as a ‘normal’ habit you’re not only helping rebalance the nervous system but also positively affecting two key elements of breathing that are affected post injury.

Breathing effects on other common concussion symptoms 

Understanding and awareness of symptoms from head injuries have typically been of things like memory loss, sleep disturbance, emotional and cognitive issues, headaches, depression, sickness and vomiting. These are the ‘classic’ symptoms that people look out for and report. Interesting most of these symptoms are the same reported by those with dysfunctional breathing.

We’ve discussed that symptom management is not the indicator for when a brain is fully healed and recovered but that are indictors of a brain in the state of acute injury, which in post concussive syndrome can last for months and even years. As these symptoms are the same as those with dysfunctional breathing, could it be that those like me who suffer for months and even years with ‘brain injury’ symptoms are actually suffering from side effects of dysfunctional breathing?

Using breathing and HRV to access brain function and recovery 

Rather than having multiple fMRI scans to access recovery, now that it is well documented in the literature that absence of symptoms is not an accurate representation of a fully recovered brain. We are proposing a non-evasive way of assessing brain recovery through breathing assessments and HRV biofeedback measurements.

How to access breathing Post Concussion

It’s important to point out that yes these can be effective breathing assessments for post concussion but what would also be great is to have pre-concussion assessments to be able to compare a baseline.
3 simple assessments to evaluate the autonomic functions, carbon dioxide tolerance and breathing mechanics of an individual;
1. Resting respiratory rate
2. BOLT Score. Relaxed breath-hold to first desire to breath is an assessment from the Oxygen Advantage that has been well used and studied within the literature
3. Hi-Low Test

Tutorials for all assessments are included in the free foundations of breathing online course here at ProBreathwork.
Also if technology is available, taking HRV using biofeedback if possible. Also if part of a sports team take these at the start of a season to have a baseline of breathing and ANS before any injuries. Use baseline testing as a comparison during any concussion recovery process alongside standard symptom management.

Exercises to improve breathing, blood flow to the brain and HRV for concussion recovery

Changing day to day breathing and sleeping habits back to nasal is a key first step. Switch to nasal breathing in day to day activities and sleep (tape mouth at night)

Exercise 1: Many short breath holds – no more than half your BOLT score whilst sitting.

Depending on severity of symptoms start with just 1 second pauses, build to 2 seconds and eventually to 5.
  • Take two normal, gentle and soft breaths in and out of the nose
  • Pause for 1 second after the normal soft exhale
  • Then take 2 normal breaths
  • Pause for 2 seconds after the normal soft exhale
  • Then take 2 normal breaths, if 2 seconds feels calming and relaxing you can gradually increase to 3 seconds and eventually 4 and 5 seconds
  • Do this exercises for 5 to 10 minutes a few times throughout the day

Exercise 2: Breathing light down regulation – quiet and even silent inhales with extended humming exhales.

Prolonging the exhalation helps down regulate the nervous system, we release a neurotransmitter called acetylcholine which reduces the heart rate. The humming automatically extends the exhale and also stimulates the vagus nerve via the vibrations in the voice box. The vagus nerve is a key communicator back to the brain for autonomic nervous system regulation.
  • Can be done sitting or lying down on your back. Try to do for 5 to 10 minutes with a relaxed sense of air hunger.
  • Do this exercises for 5 to 10 minutes a few times throughout the day.

Exercise 3: Short walking breath-holds

When able to do walking with triggering symptoms, introducing some ‘soft’ walking breath-holds of just 5 paces after a normal exhale.

Do this exercise a couple of times per day once walking is symptom free.

I so hope that you find this information helpful and it not only helps you understand the relationship between head injuries and breathing better but also helps empower you to improve brain health and recovery post injury.

I will be presenting on this in the coming months so if you are interested in learning more or have any personal or specific questions please email me at [email protected].

Thanks for reading



Barker N, Everard ML. Getting to grips with “dysfunctional breathing”. Paediatric Respiratory Reviews 2015; 16: 53–61.

Bishop et al (2017). Brain Injury. Parasympathetic baroreflexes and heart rate variability during acute stage of sport concussion recovery. 31(2):247-259.

Kastrup, et al (1999). American Journal of Neuroradiology Cerebral Blood Flow–Related SignalChanges during Breath-Holding. 20 (7) 1233-1238.

Kety SS, Schmidt CF. The effects of altered arterial tensions of carbon dioxide and oxygen on cerebral blood flow and cerebral oxygen consumption of normal young men. The  Journal of Clinical Investigation. 1948;27:484-492.

Senthinathan, A et al (2017). Clinical Journal of Sport Medicine. Heart Rate Variability of Athletes Across Concussion Recovery Milestones: A Preliminary Study. 27(3):288-295.

Watson et al. 2021. European Respiratory Review. Minute ventilation/carbon dioxide production in patients with dysfunctional breathing. Jun 30; 30(160): 200182.

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