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Mammalian Dive Reflex (MDR)

is a reflex that is hardwired into our genetic makeup and is brought on by immersion in water (particularly the face) and holding your breath. It is seen in all kinds of mammals and is very strong in children .

The MDR is essential for Freedivers to be able to remain underwater for extended periods of time, and it can be strengthened over time to improve diving performance through experience and intentional/directed practice . The main characteristics of the MDR are bradycardia, peripheral vasoconstriction, blood shift, the spleen effect,

If you’re interested in learning more about the MDR the next part will explain every part of it and how it work


bradycardia

is a physiological response to facial submersion in cold water. The normal human heart rate slows down by between 10% and 50% . Marine mammals experience changes that are even more dramatic. Slowing the heart rate reduces the need for oxygen, leaving more O2 available for use by the Freediver when underwater.

in some cases like dolphins it can slow downs to 1 bet per minute.

Peripheral vasoconstriction

is a physiological response that occurs in freediving when the body adapts to immersion in


water at deeper depths (i.e., higher pressure) . It is characterized by the constriction of blood vessels in the toes, fingers, hands, and feet, which reduces the circulation of blood in these areas . This mechanism helps to draw blood away from the peripheral areas of the body and towards the core of the body and vital organs .

As a result of peripheral vasoconstriction, blood flow to the arms and legs is reduced, making these muscles work anaerobically and diverting blood (and oxygen) to the brain and vital organs . This process is essential for Freedivers to be able to remain underwater for extended periods of time .



Blood shift

is a physiological response that occurs in freediving when the body adapts to immersion in water at deeper depths (i.e., higher pressure) . It is characterized by the movement of blood from the peripheral areas of the body (e.g., arms and legs) to the chest cavity, which increases the volume of blood in the thoracic cavity and compresses the lungs . This mechanism helps to protect the lungs from overexpansion and collapse, which can occur at deeper depths .



The spleen effect

is a physiological response that occurs in freediving when the body adapts to immersion in water at deeper depths (i.e., higher pressure) . It is characterized by the contraction of the spleen, which releases red blood cells into circulation and increases the oxygen-carrying capacity of the blood . This mechanism helps to improve the body’s ability to transport oxygen to vital organs and tissues, which is essential for Freedivers to be able to remain underwater for extended periods of time .




and this general explanation about the MDR. but in my experience in Freediving its really amazing sport and nice feeling to be underwater and to see this amazing world without the need of specialized equipment like in scuba diving for example . and if you feel like you need more info about freediving don`t hesitate to ask or chat with me by clicking here

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