Longer breath-up period

After a 2 min dive, a diver needs to rest motionless on the surface for 4-10 minutes to expel carbon dioxide from the body and to resaturate tissues with oxygen. Any hyperventillation is dangerous, because it expels too much carbon dioxide from the body and delays the urge to breathe. Always breathe deeply but slowly.

Endurance fitness

Exercise teaches the body to consume oxygen more efficiently and work under conditions of hypoxia (lower oxygen), hypercapnia (high carbon dioxide), and excess lactic acid. It improves the brain's hypoxia tolerance and increases the myoglobin content of muscles.1 High myoglobin is a major reason many aqautic mammals can hold their breath so long.

Increased blood volume

Blood volume increases with athletic exercise. More blood means more hemoglobin to carry oxygen.

Lung capacity

Lung size can't be increased, but you can use your lungs more effectively by stretching the diaphragm and ribcage before breath-holding. Some professional freedivers use a technique called "packing" to push down up to 50% more air into the lungs, but excessive packing can lead to injury.

Economy of movement

Trained divers move gracefully through the water and make no unnecessary movements.

Tolerance of urge to breathe

Holding your breath becomes more comfortable with training, as any physical exercise. It can even be a missed sensation. Learn to relax and tune into the body's signals, like the contractions of the diaphragm and the psychological urge to breathe.

Mental and physical relaxation

Stress, fatigue, and fear tax the body's oxygen reserves. You should only dive when well rested, relaxed, and completely focused on the dive. Even economy of thought can conserve precious oxygen.

Cool water on the face

Water on the face induces slowed heart rate (bradycardia) and oxygen metabolism. You can hold your breath longer after the first "warm-up" breath-holds, as the diving reflexes kick in. You can hold your breath longer in water than on land and in cool water more than in warm water. Water at depth is cooler, so depth of the dives can help stimulate diving reflexes.

Water pressure

Redirected bloodflow from the extremities to the core (peripheral vasoconstriction) is one of the reflexes triggered by water pressure, which affects breath hold time.