Below are some tips I gathered in 2017 during a seminar and workshop with Herbert Nitsch "The Deepest Man in the World".
In just one morning, Herbert helped me improve my static apnea from 45 seconds to 2 and a half minutes...
Far beyond my expectations. H Olivier Dauxais. Founder of IFDI.

Apnea

Best diver in apnea = Best energy saver

Indeed, energy consumes oxygen.

What are the 5 main points consuming oxygen?

1- The digestion of our meals is a big consumer of oxygen. We should dive in the morning before any meal.
2- Keeping the body warm also consumes a lot of oxygen. We should use a wetsuit even in the tropical waters.
3- The body loses a lot of heat through the head. The wetsuit should also cover the head.
4- Another big consumer of oxygen is the brain. So, we need to learn to calm down our brain.
5- The muscles also use oxygen. We need to minimize our movements with the use of good diving fins.
By following the 5 above points, your apnea time can be 3 times longer.

You can also train your body to tolerate a higher percentage of CO2. How to do?

By simply repeating some sessions of apnea on a bed or a sofa. But, rather than practising with full lungs, you will save time by practising with empty lungs. This also has the advantage to be closer to the reality of free diving at depth that compresses your lungs. Start your apnea after a normal exhalation. Monitor your apnea time with a watch. When your apnea time is over, inhale and exhale 2 or 3 times and then restart apnea... and so on... Remember not to use your brain during the apnea time. Don't focus on reading every second of your watch... Relax yourself. You could close your eyes or watch something relaxing on TV. See by yourself what works the best for you.
Caution: Don't practise too much. Learn to listen your body in order to train yourself with intelligence.
One week of practise is enough to considerably increase your apnea time.
Caution: The constant deprivation of oxygen is bad for the body cells. Train yourself only when you need.

Another very good tip that can extend your apnea time:

When you come to the end of your apnea time, you may have noticed that your diaphragm contracts into small spasms. This is natural. Don't refrain it. You should even trigger or amplify this spasm of the diaphragm whenever you're lacking air. You'll be amazed to discover that 1 or 2 contraction of the diaphragm "shakes and refreshes" somehow the air in the alveoli of your lungs, but more than all, it seems that this triggers the release in the blood flow of oxygenated red cells which are stored in the spleen and you suddenly feel ready to considerably extend your apnea time.

Good to know also:

The diaphragm and the flexibility of the belly is another useful tool to improve your apnea time. While lying on your back, play with your diaphragm in order to push your belly as much as possible into your thoracic cage. Then, the other way around, use your diaphragm to push down your belly in order to look like a pregnant woman. Repeat this several times. This diaphragm exercise is not only good for apnea but it's also very good for your health, in general. Furthermore, some stretching sessions of all the muscles that cover your belly also help.

About security:

Improving your apnea time includes the risk of exposing yourself to a lack of oxygen for your brain. You might lose consciousness and if you're alone in the water, you may simply drown yourself. So, never dive alone. Always dive with a buddy. One stays at the surface in order to monitor the other one who dives. Most of the cases of loss of consciousness happen at the end of the apnea time, on the way up within the last 10 meters before reaching the surface or a few seconds after reaching the surface. If ever, your buddy loses consciousness, make sure to hold his or her mouth well above the water till he or she recovers. Consult your instructor for more details.

About the pressure:

If you're not yet familiar with the changes of pressure of the underwater world, we invite you to read the 10m Diver course.

About decompression sickness:

You might be surprised to see here a chapter about decompression sickness. Indeed, for many years, we believed that the decompression sickness may affect only the scuba divers because they breathe pressurized air. But, even though a diver in apnea doesn't breathe pressurized air, it remains true that the lungs are compressed during a dive at depth. So, very logically, the air in your lungs is at a higher pressure than the surface, and, therefore, your body will absorb some of this air under pressure into your body cells through the blood circulation during the time of your dive. You may ignore this chapter if you do not dive deeply and lengthily. But, if you repeat many dives in apnea that are deep and long, you should pay attention to this chapter. Unfortunately, nowadays, this is still something rather new or even taboo. There are no result of studies that can guide you to avoid the decompression sickness after many deep dives in apnea. You may read more about the decompression sickness that concerns the scuba divers, in the 20m Diver course.

Note: IFDI focuses on the minimum information, goes straight to the point and avoids you a long reading of a book.
Of course, if you want to read more, your instructor may propose you the right book for your level.
IFDI displays very few images to allow an easy loading even in remote islands.

Reading a text consumes much less data and energy than watching a video.
By reading the courses of IFDI, you contribute to a better environment.

Edited in 2018. Updated in 2024.