In Tibetan Budhhist writings and oral tradition, Shambala is a legendary kingdom in a mountain valley behind unscalable mountains. It’s considered an enlightened place where inhabitants live free of fear, want and disease.
The benefits of training at altitude have been popular ever since the Olympics in Mexico City in 1968, sparking a wave of research into the subject matter. At the same time, researchers interested in freediving have uncovered a host of benefits of breath holding and a lower blood oxygen saturation. In the yogic breathing traditions, one of the exalted techniques is known as Kumbhaka, which involves breath retention on either an inhale or exhale.
Breath holding creates a number of changes in your body, including the potential decrease of blood oxygen saturation and a significant increase in carbon dioxide concentration, which will induce a strong feeling of air hunger. By using breath hold exercises we can replicate the lower pressure of oxygen while residing at sea level.
By recreating the low oxygen pressures coherent with altitude training, it may also be possible to improve disease resistance and general health.
What happens when you hold your breath training and during hypoxic training?
On cessation of breathing, your cells continue to use up vital oxygen and produce carbon dioxide in the process of cellular respiration.
The blood chemistry changes induced by higher levels of Carbon dioxide increase acidity, lowering the PH, (Think – Carbon Dioxide, which contains Carbonic Acid = Acid) this process in and of itself will reduce the body’s sensitivity to acidity or acidosis which in turn can improve performance.
Breath holding at different volumes improves lung capacity. As the carbon dioxide levels continue to increase the chemoreceptors will start to give off autonomous signals causing the urge to breathe, sending impulses to the diaphragm to resume breathing resulting in contractions. By relaxing into the building intensity reactions the strength and flexibility of the diaphragm improves, over time lessening the intensity.
Brain centers responsible for fear, panic and anxiety are located closely to the respiratory centers of the brain and also have chemoreceptors. These intricate processes are flexible and plastic. Voluntary breath holding allows us to stretch our bodies tolerance to carbon dioxide and increase our ability to maintain composure and perform under pressure.
Breath hold training
During a breathhold, the cells and tissues continue to use up the oxygen in the blood, eventually inducing a state of mild hypoxia. This process is also adaptive and with training, most people can learn to lower their bodies blood oxygen saturation within a few days of practice.
The upper limits of breath holding are as of yet not defined. Nor is the exact mechanism that makes up one’s ability to hold their breath for extended periods of time. A research paper by the Sports and Science faculty at the University of Birmingham investigated what determines how long an individual can go without taking that gasp for air. The best answer to date is the flexibility and responsiveness of the diaphragm communicating with the respiratory brain centers, which in turn is influenced by receptivity to the increasing levels of carbon dioxide but also, willpower and determination,
Breath hold training can boost physical performance in the following ways:
- Strengthen respiratory muscles
- Stimulate recovery and repair
- Maintain fitness at rest
- Reduce oxidative stress
- Improve carbon dioxide tolerance
- Improve aerobic & anaerobic capacity
- Improve oxygen carrying capacity
- Increase Vo2 max
Bringing the mountain to you
Decades of research in the former Soviet Union showed that Intermittent Hypoxia could achieve the same benefits as sustained exposure to high altitude conditions.
Athletes make use of various high altitude training and living environments to improve strength, speed and other aspects of performance. Over 80% of Olympic medal winners have made use of altitude training and both the Australian and NSW institutes of sport have altitude training chambers.
For the purposes of physical performance, essentially, the adaptations help increase your resistance to fatigue, as well as increasing the efficiency of your oxygen usage and energy sources during exercise. Training in this way can produce better aerobic and anaerobic capacity in most athletes.
Non athletes, including the elderly can also benefit with improvements in various markers of aerobic fitness, circulation and breathing (Burtscher, Pachinger O et al. 2004).
General health can also improve in non-athletes who spend time at moderate levels of altitude. Research shows that there can be improvement in immune function, increased anti-oxidant production, enhanced metabolic function, improved glycemic control as well as better blood flow and breathing (Singh 1977, Larsen, Hansen et al. 1997, Lee, Chen et al. 2003).
So what would happen if we could bypass the physiological limits imposed by our autonomic nervous system, and hold our breathing effectively and almost effortlessly to create a hypoxic response?
Some definitions for Breath Training and Hypoxic Training
Blood Oxygen Saturation refers to the amount of Oxygen bound to your red blood cells, usually measured at the periphery.
A Pulse Oximeter is a handheld device which measures how loaded the blood is with oxygen. It can be motivating to witness a drop in oxygen saturation as you practice breath holds, and recording the data in your breath journal will help you measure progression and stay on track.
Normoxia speaks to normal oxygen saturation. At sea-level this varies between 95 percent and 99 percent. While the benefits from breath holding can occur absent from or even in the smallest shifts, it can take a little time and practice before you notice a decrease in oxygen saturation.
Hypoxia is the state of low oxygen saturation in the body, generally anything lower than a blood oxygen saturation (Spo2) of 95%. When experienced in short doses in controlled and measured conditions, it provides the opportunity to train your respiratory system to function more efficiently, increase red blood cell count and allow for greater oxygen carrying capacity.
Intermittent Hypoxic Interval Training (IHIT) is defined as a method where during a single training session, there is alternation of hypoxia (inadequate oxygen) and normoxia (normal oxygen). This is traditionally achieved using altitude simulation devices, but can be naturally obtained through alternating breathing and periods of breath holding.
This next section provides insight into how we can safely and effectively use what we will refer to as Intermittent Hypoxic Interval Training (IHIT) to unlock performance secrets.
Intermittent Hypoxia Training Interval Techniques
In short, if we over-breathe for a period of time, lowering the carbon dioxide levels in the blood and lungs, then choose to hold our breath – particularly on the exhalation – we delay the urge to breathe which allows us to hold our breath and reach a state of hypoxia efficiently and almost effortlessly.
Below I will do my best to outline a more in-depth overview of the physiological effects of implementing this principle and propose an exercise used to consciously disrupt homeostasis, “shake” the autonomic nervous system and induce a controlled hypoxic effect. Throughout we experience fluctuations of carbon dioxide levels from normal to low, to high, changes in blood PH ranging from alkaline to acidic, whilst our cells constantly adapt and switch fuel sources. The exercise activates both branches of the autonomic nervous system alternatively and repeatedly, dancing between pressing the brake and gas paddles.
When we deliberately choose to harness the techniques and principles learned up to this point and induce a state of relaxation and parasympathetic activation, lowering our metabolic needs, then make a conscious choice to increase our breathing volume in a forceful, rhythmic manner this creates an opportunity to consciously control autonomic functions and induce great change at a cellular level.
Is Breath Training and Hypoxic Training for Everyone?
No two individuals have an identical tidal volume, lung capacity and thoracic flexibility, and the interpretations of ‘breathe deep and full’ or ‘take bigger breaths’ are highly subjective. It can be helpful for the guide to set a certain pace of breathing using audible cues, or even prompts a certain cadence. Don’t get attached to certain outcomes or prompting individuals to do it ‘your way’ and rather allow the breather to find a rhythm, pace and depth that works for them.
Instantly the lower the carbon dioxide levels present induce a vasoconstrictive effect whilst also increasing the bond of haemoglobin and oxygen. The peripheral oxygen saturation of the blood might increase slightly, rising from 95-98% to 99-100%. This indicates the bohr effect is taking place as well as sympathetic activation and a decrease in cellular oxygenation. It only takes about 30 seconds of deep breathing to reduce brain oxygenation by 40%. The reduced amount of carbon dioxide and hence carbonic acid in the blood causes respiratory alkalosis, which further induces a feeling of lightheadedness, buzzing around the ears and potential dizzy spells. Meanwhile metabolism is ramped up and the increased heart rate and release of catecholamines further increase oxygen consumption.
It can be motivating at first to wear a handheld pulse oximeter during the exercise. A reading of 85-87% SPo2 simulates training at an altitude of 4,000 to 5,000 metres (13,000 to 16,400 feet) above sea level where the air is thinner and pressure of atmospheric oxygen lower.
Renal compensation takes place to balance the weakening of the PH buffer, caused by the decrease in carbon dioxide – also known as the Bicarbonate buffer – which maintains a delicate balance between calcium and magnesium. Lack of either of these minerals can cause muscle spasms, cramps and tingling around the mouth, fingers and toes. Further compensation leads to ionisation of plasma proteins which increases the neural membrane permeability to electrolytes and causes involuntary muscle contractions also known as Tetany.
These are adaptive responses and over time, with exposure these side effects will decrease significantly. For the purposes of Intermittent Hypoxic Interval Training, it is not necessary to lead yourself or guide a participant this far into hypocapnia. Effects will be most significant on the first exposure to these techniques and can lead to severe discomfort. A cessation of breathing with or accompanied by a few minutes of slow breathing will restore the chemical balance and the symptoms will go away. It is important to inform participants of this and offer ‘a way out’.
After a passive exhale, simply stop breathing with the lungs comfortably empty at functional residual volume. Starting the breath hold and conscious relaxation phase. At this point, the decrease of carbon dioxide has caused an oxygen deficit and the cells have switched to anaerobic metabolism. Lactate and pyruvic acid are produced, causing a build up of acid which eventually lowers the PH enough for the oxygen dissociation curve to shift back towards the right and oxygen to be released from the bloodstream.
Breath holding on the exhalation provides numerous advantages in this case. The exhalation is connected to ventral vagal activity, slowing the heart rate whilst increasing relaxation. For the purposes of lowering the blood oxygen saturation, a hold with empty lungs is more effective.
The Sweet Spot of Hypoxia
The sweet spot for exhale holds appears to be around the functional residual capacity. This will vary per individual and it can take some practice to establish where we experience a balance of comfort and effortlessness in holding the breath. A forceful exhale, down to residual volume, will create tension whilst the diaphragmatic contractions might come sooner, causing further discomfort. Not exhaling enough can leave the partial pressure of oxygen elevated, delaying the hypoxic effects.
The lactate is oxidised and produces carbon dioxide, lowering the PH even further. Meanwhile, metabolism is slowed down, reflected by a lowering pulse, as we move into a second hypoxic event when the newly released oxygen is used up by the aerobic respiration, switching the cells back to anaerobic metabolism and the production of lactate.
These periods of hypoxia are relatively harmless and comparable to the lack of oxygen that occurs during intense exercise and periods of anaerobic respiration. Blood flow to vital organs remains constant and lactate is delivered to the heart and brain where it is used as fuel.
The urge to breathe is caused primarily by increased levels of carbon dioxide in the blood which is delayed significantly through the overbreathing in the first phase. Most people will find they can sustain the breath hold for up to two minutes or even above, allowing for a significant drop in blood oxygen saturation. A measurement of 85% can be achieved without much strain and is already considered severe hypoxia and will prove sufficient in causing adaptations and unlocking the benefits of Intermittent Hypoxic Interval Training.
It is possible to exercise willpower and determination to push the breathhold beyond comfortable levels but by no means necessary. When the oxygen levels drop below 60% the hypoxia will stimulate further urges to breathe. We suggest this as the limit of hypoxia. It should be noted that at this point we are chartering into mostly unknown waters and the consequences of regularly reaching states of hypoxia this significant via these types of breathing exercises are for the most part still unknown.
Metabolic rate and efficiency appear to impact the consumption of oxygen during these types of breathhold. We consistently observe those with higher muscle density to drop quicker into hypoxia.
The threshold at which the autonomic nervous system will trigger a loss of motor function or ‘blackout’ is different per individual. Most studies into hypoxia determine an ethical limit of what would roughly compare to 40% blood oxygen saturation and we propose never venturing below this level.
The lowest measured hypoxia in a paper on competitive freedivers was 44% blood oxygen saturation, recorded towards the end of a dive in an athlete. It should be noted that these athletes strictly avoid overbreathing of any sort. This indicates the lowest ‘natural’ extreme in well adapted individuals and further reinforces the above notion on ethical limits of hypoxia.
Towards the final stages of breath retention the now rising levels of carbon dioxide and respiratory alkalosis stimulate urges to breathe. An increased heart rate can also be observed indicating the sympathetic nervous system is activated, causing further discomfort.
At this point we can extend the breath hold by ‘ladder breathing’ allowing the movement of the diaphragm to pull in restricted amounts of air up to 10 times, temporarily alleviating the air hunger, without intervening with the hypoxic effects. Another strategy can be to ‘flush a breath through’ the lungs, taking a tidal volume breath in and out, continuing the hold.
The inhale hold, followed by releasing conscious control of the breathing and ‘letting the body breathe you’ starts restoring the chemistry, whilst inducing a state of euphoria. Oxygen steadily starts flushing through the tissues and repaying the oxygen debt caused by anaerobic respiration whilst the carbon dioxide levels lower. After a period of the breathing finding its natural flow we experience a deeply peaceful state, where the parasympathetic nervous system is on high, metabolism reduces significantly and the heart rate and respiratory rate lower. Allowing for further relaxation and reduced mental activity.
The remarkable health benefits of Intermittent Hypoxia, Breath Training and Hypoxic Training
Dynorphin is an endogenous opioid involved in the pleasure / pain balance, addiction, and mood regulation which increases the number and sensitivity of endorphin receptors, priming the body to experience greater euphoria as a result.
Apoptosis is the process of programmed cell death. Hypoxia and fluctuations of blood PH stress cells’ adaptive processes, stimulating rejuvenation. This process is beneficial in eliminating potentially virus-infected and cancerous cells.
Stem Cells are special human cells that are able to develop into many different cell types.
A potential benefit from intermittent hypoxia is the mobilization of bone marrow stem cells and mesenchymal stem cells which have low numbers of mitochondria, and are more adapted to anaerobic survival rather than oxygen rich environments.
In 2019, the Nobel Prize for physiology was awarded for the discovery of Hypoxia Induced Mitogenic Factor, which when released by breathing exercises can naturally stimulate the production of new mitochondria and improve cellular efficiency.
Tumor protein p53 is also known as the ‘guardian of the genome’. This protein is activated during a hypoxic event and acts as a tumor suppressor, which means that it regulates cell division by keeping cells from growing and dividing (proliferating) too fast or in an uncontrolled way.
Functional hypoxia drives neuroplastic effects as well as Neurogenesis, the process by which new neurons are formed in the brain, through the production of erythropoietin in the brain which has been shown to improve cognition.
Hypoxia Inducible Factor (HIF-1) leads to production of vascular endothelial growth factor (VEGF. It is also associated with increased anaerobic threshold and blood lactate kinetics.
Variations in oxygen levels in the blood are sensed by specialized cells in our kidneys that make and release the hormone erythropoietin (EPO). This hormone is a known performance enhancer andR increases the oxygen carrying capacity of the blood.
Nitric Oxide increases production of nitric oxide. This, has the short term effect of increasing cerebral blood flow producing endothelial nitric oxide. The end result is neuroprotection of various pathologies, reduced blood pressure and a reduction of oxidative stress.
The end result of hypoxic adaptation is improved oxygen, better circulation and improved mitochondrial function. Also, increased tolerance to various stressors and even toxic chemicals and also reduced inflammation. The adaptive changes enhance physical and mental capacity, so that the body is better able to cope with a range of stressors and repair and heal cells, tissues and organs.
This refers to the principle of cross adaptation. Stress-related diseases such as hypertension, heart disease, ulceration of the stomach or duodenum, diabetes, dermatological diseases and autoimmune conditions have all been shown to improve with both exercise and intermittent hypoxic interval training. Protection comes because the body becomes more tolerant and resistant to stress in general.
The Benefits of Breath Training and Hypoxic Training have been Shown to Translate to:
- Increased tolerance to physical load
- Enhanced power output and speed
- Improved quality of life
- Reduced symptoms of depression
- Improved quality of sleep
- Decreased blood pressure and heart rate
- Improved quality of life
A day to day increase in activities was also shown. This indicates that the overall positive effects on wellbeing create more energy and motivation. Also, an improved mood and willingness to try new things.
The minimal effective dose of Breath Training and Hypoxic Training
There has been extensive investigation into the effects of Intermittent Hypoxia in recent years. The therapeutic potential depends on ‘the dose’.
Interestingly, it appears that when provided at the right doses, the adaptive benefits caused by the periods of hypoxia induced by breathing techniques can have a directly opposing effect to the deleterious effects hypoxia can cause to those with sleep apnea, stroke or infarct.
The hormetic effect is at play here. Basically, the right amount of exposure, for the right amount of time, creates the minimal effective dose.