Avoiding Blackouts And Hypoxic Threshold In Freediving


It is absolutely important for every beginner freediver that they take a course before making their first dive. One of the main reasons why is because you learn to avoid certain risks and freediving mistakes. Top of the list is the risk of freediving blackouts and hypoxia which can ultimately result in drowning and death.

This is how to avoid blackouts and hypoxic threshold in freediving. But first…

What is freediving blackout and hypoxia?

Freedivers practice how to hold a single breath for as long as they can. However, if the breathing technique is not in the correct form, then you could experience a blackout.

Freediving blackout is the loss of consciousness brought by the lack of enough oxygen to the brain. This lack of oxygen is called hypoxia.

If a diver loses consciousness when underwater, he or she might drown. This is why practice and having a dive buddy with you at all times is crucial. you will also learn to use the 10 essential pieces for freediving.

Divers that have experienced a freediving blackout and lived to tell the tale to speak of being in a state of euphoria. They report slowly drifting into a dream and being suspended. There are also beautiful lights and sweet music that would put anyone in a state of complete and utter bliss.

Others have not been so fortunate and every year there are cases of freediving deaths.

Three Main Types Of Freediving Blackout

1. Shallow/ Deepwater blackout

This occurs when the freediver is making his or her ascent from a deep dive and will normally happen under 30 feet. As the diver comes up, the surrounding water pressure reduces. As a result, the lungs expand pulling oxygen from the body tissues and limiting oxygen from the brain.

It is this that causes the diver to lose consciousness resulting in the swallowing of water and eventual death.

2. Static apnea blackout

When it comes to static apnea the freediver is not experiencing any kind of pressure. Instead, it is a direct result of hyperventilation. Beginner divers are at risk of this type of blackout as they tend to hyperventilate the most.

When you hyperventilate, you rid your blood of carbon dioxide, this exercise is meant to allow the diver to dive much deeper and stay under for longer. However, there is a risk to this. The arteries that are responsible for carrying blood to the brain will constrict. This is part of the mammalian dive reflex and also includes freediving blood shift and spleen reflex. This means they will not deliver enough blood and the brain is starved of oxygen.

The result is a static apnea blackout.

3. Surface blackout

This type of blackout occurs when the diver manages to reach the surface but blacks out before he or she can take in enough oxygen.

This is one of the main reasons why your dive buddy should keep an eye on you for at least 30 seconds when you resurface.

Other factors that can cause you to breach your hypoxic threshold include lack of proper diet, hyperventilating, and lack of proper breathing techniques, lack of good freediving training and practice, stress, hyperthermia, and dehydration.

How to prevent freediving blackouts


Never hyperventilate. This is the first thing you should observe to prevent the occurrence of blackouts and hypoxia.

Always ensure that you take a freediving course and that you have an instructor with you at all times. He or she will analyze your breathing and correct any flaws. When it comes to doing the actual dive, you will be confident knowing that you are doing it the right way.

It is also important to have a good freediving watch.

Thirdly make sure you progress in your freediving gradually and do not push your body too far. Over time you will be able to develop new limits and break old records. Your body will gradually become used to dealing with more pressure and less oxygen. Some divers will look forward to experiencing a freediving blackout to know where their limits lie.

But this is absurd, by the time you experience a blackout you have already crossed your limits. As soon as you feel like anything is out of place and that you are unsure of the dive, pull back and try again next time.

The practice is the key is to become good at anything. You can build on your arsenal of experience. As much freediving involves careful planning, everything will not go according to the plan 100% of the time.

The line may be set at the wrong depth, you may fail to hear your depth alarm or your dive buddy may fail to meet you at the agreed depth. With experience, you will be able to handle situations calmly in case things go wrong. Panicking after all is never the right thing when freediving.

Also, it’s important to ensure that you are not cold, dehydrated, or tired. When you are cold, your body will shiver which causes you to burn more energy and thus more oxygen. The less the oxygen levels, the likely your chance of experiencing a freediving blackout.

Ensure you have the best freediving fins when making the dive as these have a big impact on your progress and movement in the water.

It’s also important that you ensure that you are well hydrated. Dehydration thickens the blood. The heart is going to pump harder to transport the blood where it needs to go. This will also mean less oxygen circulating and reaching the brain,

You might also like: History Of Freediving

Globo Surf Overview

Freediving blackouts are one of the greatest risks that can happen to a diver. They can cause you to inhale water and eventually drown. Proper training and practice ensure that you minimize the risks of experiencing a blackout. It is always a good idea to go through the freediving safety guide before making a dive.

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