Decompression sickness in Freediving

Is it possible to have DCS for Freediver? Unfortunately yes…But at the same time, it is quite easy to put the risk at the minimum. At our school, we normally discuss in details this topic at PADI Master Freediver course, so here are our thoughts on this subject…

DCIM101GOPROG0063938.JPGIn scuba diving, when you are breathing compressed air underwater, your body is saturated more and more with Nitrogen (79% of the air is Nitrogen). The chain looks like this – you breathe in the compressed air from a scuba tank and now the pressure of N(Nitrogen) in your lungs more than in your blood, so, it going to your blood. And now in your blood pressure of N is higher than in your tissues, so, it is going to your tissues. Until you have an equal pressure of N everywhere (this is what we call saturation). And when you start coming up, opposite happens. Now pressure of N is smaller in your lungs, so the reverse process is happening – from your tissues N going to the blood and then to your lungs and then you exhale it. But it doesn’t happen that quickly. In some tissues, this process is slower than in others.

So, this is why when scuba divers coming up, they need to do it slowly (in this case N slowly coming from your body with every exhale) and they also need to have a long surface interval between dives (to release as much N from their body as possible before the next dive). And why they can spend the only a certain amount of time on certain depth (not to get too much N to their tissues).

dcs2If they violate these rules, they have a very good chance to have DCS! Without making it too complicated, DCS is when molecules of N combined in your blood (or tissues) in the form of a bubble and can cause very serious damage!

But why it can be an issue for Freediver?
Among the first, spearfishers who were shooting fish relatively deep (around 20 meters) noticed that after the long session they have symptoms which are commonly associated with “bends” (another word for DCS). So, imagine you dive to 20 meters. On the surface, you did big inhale and bring this air (and around 79% of it is nitrogen) to 20 meters, where the pressure is 3 times higher. So, the pressure of any gases inside your lungs (we call it partial pressure) going to be also 3 times higher. If the pressure is going to be higher in the lungs, then it will go to your blood and further to your tissues in the attempt to reach equilibrium. When you start your ascend, the reverse process will take place. But not 100% (some of our tissue need time to release N2). Some N2 will still be in your tissues. Very very small amount. Not a dangerous amount. But then you are going to do 50 dives more to this depth. And now you have much more N2 in your blood. And on your next ascent, it can forms bubbles and this is DCS….

There are also some predisposing factors which can increase the risk of DCS. Let’s name a few

  1. Dehydration
  2. Exercises
  3. High level of CO2
  4. Cold
  5. Not enough surface time

As you can see, spearfisher who is doing a long session with relatively deep dives and DCIM101GOPROGOPR9056.JPGsmall recovery time has a very good chance to get DCS….What to do, if you are spearfisher? Limit duration of your spearfishing session, have enough rest between dives, use appropriate thermal protection, stay hydrated!

Ok, what about DCS for Deep Freedivers?

Let’s say you are one of the most famous Freediver of all time, Herbert Nitsh, and diving not to 20 meters but to 214 meters!! You make a big inhale as possible (don’t forget, around 79% of inhaling air is N2) and put it under a huuuuuge pressure of 21 atm (this is what you have at 200 meters). During your descent, this N2 from your lungs will come into your bloodstream and from there to your tissues.
And now you will start your ascent. It would be No Limit discipline and you are not going to use your muscles for going up (which is very good to reduce the risk of DCS), you are probably also not dehydrate it nor cold (which is also very good)
But you are quite fast for this huge amount of N2, dissolved into your tissues. The bubbles will form. But not big in the beginning. But when you ascent with the constant speed, they are going to increase in size (because the pressure is decreasing). How to prevent it? You need to stop…And this is what Herbert did – he made a first safety stop at 70 meters (for 30 secs) and the second stop at 30 meters (for 60 secs). But the closer you are to the surface more important your speed is going to be. This is why he dramatically decreased his ascent rate after 30 meters (from 3 m/s to about 1 m/s). And this is how he became The Deepest Man on Earth by making a dive to 214 meters!!
But later, when he was trying to beat his own record he lost his conscious on his way up and failed to do all of the above (safety stops and slow down his speed). As a result, massive DCS….Luckily (actually his story of recovery is almost like a miracle) he survived and recovered from it!

But if you are diving not that deep, let’s say to 40 meters; is it possible to have DCS? And the answer is yes… Last year Freediving legend William Trubridge got DCS during his routine training. I mean routine for him but crazy for all of us! Let’s have a look at it

William did 5 dives to 40 meters with “hangs”. Time of each dive was about 1.50, the surface time between dives only 2.15. As a result, after his 5th dive, William felt one of the symptoms of DCS – numbness in his leg. He went to a hospital and took special treatment for DCS there (pretty expensive!).  This story has a lucky end as well, William completely recovered and competing again!

According to him, he done this type of training before (even harder) and never had any problem.

So, what is the problem here and how to avoid it? The dives were not too deep and not too long (especially if you are World Champion). But the recovery time was quite short.

So, if you are just starting freediving – this is a basic advice – DO have long surface intervals. How long? Here a couple of ways how to count it

  1. The time between your dives should be 3-4 times longer than your dive time. For example, if your dive time 30 secs, then have a rest for at least 2 mins
  2. Divide dive time by 5 and the result is a time in minutes. If you dive to 40 meters, have a rest for at least 8 mins.

And be even more conservative – have even longer rest!

A few things which I would you to remember

dcs3First of all – symptoms of DCS. Type 1 DCS – skin rash on shoulders and upper chest, joint and limb pain. Type 2 DCS – peripheral tingling and numbness, unconsciousness, respiratory arrest and paralysis, coughing, feeling of air-starving.

Second – predisposing factors. Obesity, intense exercise less than 12 hrs before diving, age, fitness level, dehydration, injury and illness, alcohol, carbon dioxide, cold. Obviously, scuba diving before freediving is absolutely no-no!

Treatment for DCS – the patient should lay down and breath 100% O2. Transportation to a recompression chamber should be organized as quickly as possible.dcs4

And one more times how to avoid DCS

  • Don’t freedive after scuba diving
  • Have enough surface interval
  • Don’t ascent very fast from the deep dive
  • Reduce the number of deep dives in one session
  • Limit the duration of the dive session
  • Stay hydrated and use an appropriate wetsuit
  • Don’t consume alcohol and don’t do intense exercise before a session

Stay safe, enjoy Freediving and educate yourself about the activity which you love!

 

Thank you for reading! If you like this post please consider to follow us and we will provide you with the essential information for Freediving!

If you have any question, feel free to ask in comments below!

 

Breathing for Freediving (part 1)

Let’s start with understanding why we (as humans) breathing. Yes, we all know that we need O2 (oxygen) for our life and this is one of the main functions of our respiratory system – bring O2 to our tissues.

But do you know that our breathing rate is mainly regulated by the amount of CO2 (partial pressure of CO2) in the blood, not O2. We even have a specific part of our brain responsible for this regulation. It has a very difficult name – Medulla Oblongata. This “thing” is responsible for such automatic functions as breathing, heart and blood vessels function, swallowing, digestion.

Why is it important to know, especially for beginner Freedivers?

Well, we all know that some of our tissues couldn’t operate without O2 even a short amount of time. For example – our brain. And when beginners hold their breath and feel the desire to breathe, they start to be nervous because they are thinking the level of O2 critically low! And it is becoming dangerous!

And – if not, why they feel uncomfortable?

Let’s say you are holding your breath for a minute.

DCIM101GOPROGOPR7790.JPGEven 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?

Our main respiratory muscle is our diaphragm. It is a big muscle between your chest (thoracic) cavity and abdominal cavity. When you need to inhale – your diaphragm going down (contraction of the diaphragm), chest volume increase and the air suck in. Reverse process happens when you exhale – you relax your diaphragm and it is coming to its normal position, pushing the air out of your lungs. Intercostal muscles (muscles between your ribs) involved as well, helping you make a bigger inhale or exhale.

And now let’s come back to urge to breath. When you are holding your breath and have diaphragm2an urge to breathe – it is simple contractions of your respiratory muscles (diaphragm for example), which are trying to remove CO2 from your body.

As a beginner, you want to stop holding your breath after you have a contraction, or a few seconds later (5-15 is a good start). But with the practice, you can hold your contractions much longer. And let me remind you, that contractions are not connected with the level of O2, it is a simple response of your respiratory system for a high level of CO2. So, you are safe when you have them, don’t be scared.

But what exactly happens with the air, when it comes to our lungs? You inhale fresh air lungs(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.

Your alveoli are tiny compartments where gas exchange happens between your lungs and your blood (capillaries). The wall of alveoli is thin enough for gas (gas traveling both directions, from alveoli to blood vessels and back) and not thin enough for liquid (this is why blood normally couldn’t penetrate into your respiratory system).

So, from alveoli, O2 moves into your blood, where most of it binds with the hemoglobin and use it as a taxi to get to different tissues (your muscles for example) through arteries.

alvioliAnd 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!

Pretty simple, right?

A few words about the importance of CO2 in our body.

If CO2 is just a byproduct of producing energy and our “urge to breath” depends on it, might be we need to remove it from our system before a breath hold activity? And then can stay underwater longer?

Probably same thought had freediving pioneers when they were doing hyperventilation (which is a big no-no nowadays). Basically, hyperventilation (or over breathing) is the process when you ventilate your lungs too fast.

What happens when you do hyperventilation – you reduce the level of CO2 in your body,DCIM101GOPROG0048084.JPG 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).

So, CO2 playing an important part in keeping pH of our blood constant (7.34-7.45), so-called acid-base homeostasis

 

Thank you for reading! hope you found some useful information here 😉

If you are the first time on our website, consider following us, we are trying to bring useful information about Freediving here!

If you have any question, feel free to ask in comments below!

PADI Freediving Key Standards

There are 4 types of certificates which you can get doing freediving courses with PADI:

  1. Basic Freediver, which is advisable for students under 15 years old. In the meantime, the youngest age for this course is 12 years. Minimum static breath hold is 90 seconds, Dynamic apnea (horizontal) at least 25 meters. Only Confined water sessions are foreseen for this level with maximum depth 6meters.
  2. Freediver, which could be unofficially called 1st level. The minimum age for students is 15, but till 18 years depth requirements are not so high. Or better to say – not so deep 🙂 So in frames of this course, we have minimum 1 confined session and 2 open water sessions. You will become a certified Freediver as soon as you: can hold your breath up to 90 seconds, can swim underwater in fins at least 25meters (horizontal) and reach minimum 10 meters depth in constant weight (simply saying diving in bifins). Maximum depth for Freediver is 16 meters constant weight. There are certain requirements for rescue skills at this level, which can easily be explained – as PADI Freediver you can train on your own with certified freediver buddy. Which means both of you should be aware of safety and how to provide some rescue in case of shallow water blackout or LMC.20180325_083650
  3. Advanced Freediver, which could be considered as 2nd level, consists of at least 1 confined water session and 2 open water sessions. Minimum static breath hold should be 2 minutes and 30 seconds, dynamic apnea in fins at least 50 meters and constant weight dive – minimum 20 meters.fisheye Maximum depth for this level is 24m. It also should be mentioned that to apply for Advanced Freediver you must get EFR first. That is also simply explained with the possible necessity to provide first aid to your buddy. And of course more advanced rescue skills should be demonstrated at this course.
  4. And finally almost professional – Master Freediver. Let’s say that is the last level “for fun”. Next step would be Instructor. So to become Master (of Freedivers Power). Minimum depth to follow the path of Freediver Jedi is 27 meters. In frames of this course, your static breath hold should be at least 3min 30sec and dynamic in fins at least 70 meters. Besides, you will start learning mouthfill, no fins diving and few other cool things as managing the rope and buoy. After completing this course you cannot teach freediving but you can assist to the instructor during the courses.

Hope it’s a bit more clear now with PADI requirements for each level of freediving course.

Soon I will prepare this article in the Russian language 🙂

 

How to hold your breath

The basic skill which you learn on your first Freediving course is, of course, how to hold your breath! This Freediving discipline requires a minimum of Freediving equipment!!

A lot of my students, when I ask them, how long they can do it, answering – 30-40 seconds. And then in 10 minutes, they can hold for 1.5-2 minutes! Magic? Not really 😉 Simply understanding how to do it correctly, what happens in the organism during static breath hold – helps that much!

Watch how our student does it for the first time! Interesting to try? Come to Koh Tao (Thailand) and we going to be more than happy do Freediving course with you!

5 Rules for snorkelers

“Rules for snorkelers? I thought there are no rules!”

AdventuresOk, snorkeling is a natural activity for us humans (especially after we invented a mask) and everyone can do it without any education.

But as usual, if you want to do something safer – you should learn how.

And let me help you with that by sharing five safety rules for snorkelers!

Below is a short version, full version, as usual on my YouTube channel – Crystal Freediving 😉

Freediving vlog

Ok, it was a long time ago when I decide that I want to do Freediving blog. But writing in English is difficult. And after finish my first blog I was correcting it again and again until I just deleted it 🙂 Apparently with video it much easy since you posted – IT IS DONE!

That’s why the transition from blog to vlog was logical. And here we go, I am a vlogger on a YouTube! 😉

It is not the first episode, but since now I am going to post here a short version of it here. Hope you, my reader, will enjoy it!

If you are interested and want to see full version, find my channel on YouTube – Crystal Freediving