Quite often, I start a beginner Freediving course by asking my students whether they think freediving is a dangerous activity or not. Some say yes, some say no, it is absolutely safe.
The truth is somewhere in the middle.
If you follow safety rules, Freediving is safe and enjoyable water-based activity. But if you break these rules, then Freediving becomes a Russian roulette without guaranteeing of a happy end.
And one of such rules is – don’t do hyperventilation before a breath hold!
But first of all, what is hyperventilation?
Hyperventilation is over-breathing – when you breathe more than you need to. Usually, the rate and depth of your breathing depend on a current metabolic activity (mainly on how much CO2 you produce). So, more CO2 you make – deeper or faster you breathe.
For example, when you are sleeping, you are not producing that much CO2, and your breath is shallow and quiet. But in contrast, if you are running, you create much more CO2, which dramatically affects your breathing rate and depth.
Back to Freediving. Remember, how breath-hold looks like? Relaxations breathing, breath-hold itself, and recovery breathing after.
Relaxation breathing can vary among freedivers, and we like to experiment with it. And some freedivers intentionally or unintentionally can do hyperventilation instead of relaxation breathing.
Why would someone do it intentionally? Is it an attempt to bring more O2? Unlikely, since the vast majority of O2 in your body is already connected with hemoglobin, this will not be affected by manipulation with breathing.
The answer is that someone does hyperventilation to decrease CO2 in the blood and delay the urge to breathe.
And what about unintentional hyperventilation? It can happen with a freediver who thinks that only fast breathing is hyperventilation. For example, you can hear such advice as “exhale as twice longer as inhale.” This is indeed a mild version of hyperventilation
But why is hyperventilation is not a good idea for Freedivers?
1. HR will go up. If you do deep and fast breathing, your heart rate will inevitably increase. And the heart is the muscle that requires O2. The more it works, the more O2 it consumes.
2. Lower CO2. Think about your urge to breathe as an alarm clock. When you have it, consider it a signal that you might come close to your hypoxic limit. If you remove too much CO2 by hyperventilation, you can come too close to your hypoxic limit and have a Black Out.
3. Also, removing too much CO2 will increase the blood pH level, making it alkaline. It will lead to cerebral vasoconstriction (constriction of the blood vessels in your brain), and as a result – less blood, less O2 will be delivered to the brain.
4. Hyperventilation suppresses the Bohr Effect. The presence of CO2 makes an easier O2 release from hemoglobin. If CO2 goes down, this mechanism is not working that well anymore.
Bottom line – hyperventilation should be avoided by beginner and intermediate freedivers by all means! It doesn’t give you any benefits but puts you at unnecessary risk.
More about Hyperventilation here
Stay safe!
DR is activated when our face is cooled (by cold water for example) or when we hold our breath. When we do both – even better!
reduction of HR for Freedivers (up to 50% or more in highly trained athletes). There are stories with even more impressive results, but let’s skip them now. Sounds impressive? How about this – laboratory rats have 80% decreases in HR while submerged underwater!!
Peripheral vasoconstriction (PV) is a narrowing of the blood vessels to reduce blood flow to non-vital organs (such as skin or inactive muscles, for example) ensuring that oxygen-sensitive organs like the brain or heart receive enough O2 for normal function. In another word PV is a redistribution of blood to vital organs from peripheral organs. PV also induces anaerobic metabolism, with an increase in lactic acid as a by-product. Interesting that the release of lactic acid into the bloodstream doesn’t occur (or at least significantly reduced) until Freediver resurface (at least this is what experiments on laboratory rats show).
why while Freediving you want to pee much often! As you know part of DR is PV and it causes increased blood flow to the torso area and increased blood pressure as a result. Our body detects it and releases a specific hormone responsible for liquid regulations, which increase urine production. Don’t be embarrassed because of it! But make sure that this reflex doesn’t make you dyhadrated (drink enough before and after Freediving session).
First one, let’s call it “old school” relaxation breathing is when you are trying to slow down breathing rate by extending your inhale and especially exhale part. There is even recommendation – exhale twice longer than inhale (not sure why twice). Let’s be honest – it is a mild version of hyperventilation (if you extend your exhale over a period of time, you removing extra CO2 from your body). I think Goran Ccolak said in his interview to Freediving Café, that every breathing, which differs from tidal breathing is hyperventilation. The question is how big ;-).
extending the duration of your exhale, do tidal breathing and then just 1-2 big breath in (with passive exhale) before actual breath hold. Same breathing what you have before you fall asleep. Still better to use diaphragm breathing for it though (it means that you still want to learn and practice it). Let’s say for two minutes you are doing tidal breathing. You relax your muscles and mind. Your heart rate will go down since you are more and more relaxed. And your CO2 level not going to be high as well. But at the same time, it is not going to be below the normal level for this particular level of activity.
The answer is – try to become as much relaxing as possible. Easy to say, hard to do. What I recommend for my beginner students is to “scan” their body during breath hold and check if their muscles relax or not.
still have plenty of O2. Enough for every body’s cells. And you know that and this is why you are keep holding.
Another important rule – do recovery breathe every single time, not only when it was “hard” dive. Even after very easy dive you need to do it – it will help you to create a very useful habit and put it on a subconscious level!
Even if you are relaxed as much as possible, you still produce some energy. And as a result, produce some CO2. And when your CO2 reaches a certain level you want to breathe (actually you want to remove excess CO2 level). In Freediving quite often we use the term “urge to breathe”. So, how are going to bring new air to your lungs? What is the process looks like?
an urge to breathe – it is simple contractions of your respiratory muscles (diaphragm for example), which are trying to remove CO2 from your body.
(only 21% is O2, 78,96% N and 0.04 is CO2) and it starts its journey into your circulatory system! There is a natural dead space (no one dies, there is just no gas exchange) on its way (nose/mouth + trachea + bronchi + bronchial), so when air reach your alveoli, it has less O2 than you when you inhale.
And within your tissues, cells use O2 for producing energy and also creating CO2 as a byproduct (as well as water). After CO2 produced, it goes to your blood (partially connected with hemoglobin, but mostly dissolved into the plasma – bicarbonate) and then going through veins to your lungs. Then again, through gas exchange, CO2 penetrates to your alveoli, going all the way up to your mouth and then you remove it through exhaling! This how we are breathing!
which cause increasing pH of your blood (blood become more alkaline – respiratory alkalosis) and it triggers Bohr effect – now a connection between hemoglobin and O2 becomes stronger and exchange between capillaries and tissues becomes harder. In simple words – even if enough O2 present in the blood, it is much harder to deliver it to tissues. Since the human brain is very sensitive to the lack of O2, as a result of hyperventilation we have symptoms – dizziness, tingling in the lips, hands or feet, headache, weakness. Or in a worst case scenario – unconsciousness (our brain simple protect us from further depleting of O2).