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About freediving
Freediving is characterized by two physiological processes:
- a breath-hold (apnea)
- lungs and chest changes caused by increasing water pressure
Apnea
The word apnea has its origin in Greek and it means without breath. During this process a diver doesn’t inhale although this doesn’t mean he has no oxigen at all. Cell processes in a freedivers body are continuously consuming the inhaled oxygen. At the same time the level of CO2 in the body increases.
A length of a breath-hold is not only a matter of one's lungs capacity, but also of the ability to relax and to slow down one's metabolism and consequently by that to lower the consume of oxygen and the production of CO2.
Breath hold
During a breath-hold, the level of CO2 keeps increasing, wich provokes the respiratory system to want to exhale. This process has several stages. It starts with an unpleasant feeling like a burning sensation and grows into strong contractions of the diaphragm, which, by its contractions, tries to force the lungs to exhale.
A normal healthy person should be able to hold his/her breath for 1 minute. So, how is it possible that freedivers are able to hold their breath for 8 minutes or even longer? The answer is hidden deep in our instincts, in what is so called – the diving reflex.
Diving reflex
Mammalian diving reflex is an ability due to which cetaceans, seals and other sea mammals are able to dive into great depths and hold their breath for long time. In simple words it means that psycho-physiological changes lead to reduction of consumed oxygen by decreasing metabolism activity, lowering heart rate and by shifting blood from peripheral parts of body to vital organs.
When even an untrained person starts a breath-hold his/her heart rate drops 5 – 7 %. As soon as his/her face gets in contact with water the drop of heart rate reaches 20 %. Hydrostatic pressure plays a significant role and in extreme depths it can lower heart rate to extreme numbers around even 10 beats-per-minute.
Together with cetaceans even man possesses an ability of blood shift. It is a state which comes after some time of a breath-hold and it means that blood is shifted from peripheral parts of a body to vital organs (heart, lungs, brain). This process extends time in which our body is able to function in a breath-hold state.
Man also has an extra mechanism wich helps the transport of oxygenized blood - a spleen. During repeated dives it releases inactive red blood cells carrying oxygen.
Occurrence of all these abilities in a man led to a theory of so called water monkey. It says that our predecessors came from the sea environment rather than from the trees of African savannas. This way or another, these abilities are a real gift which enables us to spend tens of seconds under water in a true connection with surrounding environment.
Water pressure
There is one more difficulty that freedivers, who dive into greater depths, have to face - the increasing pressure of water affecting our body. Even here it applies that mother nature has equipped man with an ability to deal with this difficulty.
Not long ago, in 1950s, doctors thought that water pressure in depths under 50 meters is so high that it would cause lung and ribcage to collapse. They were very surprised when Enzo Maiorka reached this depth in 1962. Our lungs are able to compensate the pressure in depths by increasing the volume of its capillaries by filling it with blood plasma which is fluid and therefore incompressible.
Everyone can do it
As you can see a man possesses an unsuspected potential for breath-hold diving. It all can be wasted if we don’t accept these abilities as natural and even somehow pleasant and fascinating. Finally, we come to a conclusion that a perfect control of senses, relaxation of body and soul are a key to a successful freediving.
When you don’t fight the negative feelings and even waft on them, you can discover unsuspected dimensions of your body and mind. And it really doesn’t matter whether you beat world records or just spend few tens of seconds under water observing colorful life of a coral reef.