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Not all freedivers have access to unlimited depth all year round. Some of us live in parts of the world with no access to the sea whatsoever, and others live on coasts where only shallow water is accessible. Deep freediving requires a slow progression, in order to get the body and mind adapted to the depth. For freedivers who only get the chance once or twice a year to go on holiday to places with unlimited depth, they usually work their way slowly back to deep diving, over the course of a week or two, and once they are finally in shape to start increasing their maximum depth, it is already time to fly back home! So the question is, how to keep body and mind in shape year-round, in order to get back to our maximum depth in the minimum amount of time once we get access to it.
There are many components necessary to achieve a nice and pleasurable deep dive. First, deep diving requires good flexibility, to withstand the great pressures endured at depth without damaging the body. Another component is equalization, especially of the middle ear. Deep divers also require a confident, strong and relaxed state of mind. Finally, past a certain depth, the strength of mind in itself is not enough: we also need the physical fitness and strong muscles necessary to swim, pull or kick all the way back up!
Thankfully, there are a number of ways to maintain, train and improve on all these points year-round wherever you are in the world, on dry land, in a pool, or even with shallow-depth exercises if you are lucky enough to have access to open water. Here are some of the ways to keep your body in shape and ready for a smooth return to depth. Note that these exercises should be first learned and practiced with a qualified instructor in order to execute them correctly and get their full benefit, and avoid injury.
Deep diving requires very good flexibility, to adapt safely to the great pressures experienced at depth. For a reminder, at 70m, there are 8 bars of pressure, which is as if there were 8kgs of weight on each cm2 of your body. At this depth, your lungs are compressed to 1/8th of their original size, pretty much the size of oranges! Therefore, freedivers need very high flexibility especially of the lungs, diaphragm, and chest muscles, to withstand this kind of pressure. This is what requires the diver to progress slowly, increasing depth meter by meter, to prepare the body gradually. Thankfully, flexibility can be maintained and even improved year-round, by doing regular exercises in shallow water or even on land, anywhere in the world.
A good way to work on flexibility is to do regular stretching of the whole body, stretching every single muscle properly and separately. This can be done either through a regular stretching routine or with Yoga practice. Stretching can be done as often as wanted, and at any time during the day, but preferably on empty stomach. It is definitely recommended to stretch properly before a deep dive, in order to prepare the body to accept depth. Moreover, a stretched muscle consumes less oxygen. Yoga is a very good way to improve flexibility. It is no coincidence that many freedivers also follow a regular yoga practice. The sun salutation for example is a good way to prepare your body for the day, or as a dry warm-up before a deep freediving session. There are many different styles of yoga to choose from, depending on your goals, abilities, and preferences. For flexibility work, Atha, Yin, and Ashtanga are particularly effective.
Stretching can also be done on full lungs, or using packing and reverse packing on land, to work on the flexibility of your chest muscles and increase vital capacity over time. However, be aware that these are advanced exercises, and should be done cautiously, increasing extremely slowly, otherwise it is possible to damage your lungs.
To improve the flexibility of the diaphragm there are several exercises, especially coming from Pranayama yoga, that can be done regularly, every day if you want to. For example, Kapalabati is great to strengthen the diaphragm. It is also a good way to clear your nose and sinuses! This exercise can be practiced regularly on land, however, it should be avoided right before a depth session, as it is pure hyperventilation. Udyana Banda is another excellent exercise for freedivers, to improve the flexibility of the diaphragm. The exercise itself, by bringing the diaphragm up under the ribcage, actually mimics what really happens during a deep dive. Udyana Banda is great to prepare the diaphragm, stretch it and make it flexible, so it will easily go up when the lungs get compressed at depth. You can practice this exercise every day year-round, to keep your diaphragm in shape, ready to accept the pressure during deep dives.
Hypopressive gym is a method that was developed in the 80s by Marcel Caufriez, when studying post-partum patients. He found that diaphragmatic «aspiration» was reducing organ prolapse and incontinence. These exercises are done on breath-hold after a full exhale, therefore very similar to Udyana Banda. "The ribcage is then expanded, creating a depression (hence the name «hypopressive»), that will suck the diaphragm inwards. In response to the decreased pressure, there is an involuntary contractions of the type I muscle fibers of the pelvic floor and of the abdominal muscles". A whole hypopressive routine takes about 10-15 mins and can easily be done daily, preferably in the morning, on empty stomach. There are many benefits: exercising core muscles, abs, back, pelvic floor, and of course for us freedivers, it is working on the diaphragm and on an exhale breath-hold.
Another tricky part of deep freediving is the equalization of the ears. This is what will stop most divers in their progression and can sometimes require a lot of time to work on, train, and overcome equalization limitations. BTV, (Béance Tubaire Volontaire, i.e. voluntary tubular opening), is a technique by which we can open the Eustachian tubes voluntarily by controlling the muscles around them, and thus, equalizing hands-free. There are many exercises that can be done at home, in front of the mirror, over several weeks, to stretch, strengthen, and increase awareness and control of the muscles around your Eustachian tubes. Even if these exercises do not take you all the way to the point where you can hands-free equalize underwater, they will at least definitely make your usual equalization easier and smoother.
Most freedivers use Frenzel and/or Mouthfill techniques to equalize their middle ears during a deep freedive. These techniques require good awareness and control of your tongue, jaw, soft palate, and glottis. Here also, there are hundreds of exercises that can be done on land or in shallow water, to practice and master these techniques. It is recommended to get help from a qualified instructor, who will explain and show the exercises, check how you perform them and correct the mistakes if needed. Some small tools such as an otovent or an EQ-Tool from Uba Project, are very well worth the investment and very helpful when practicing equalization.
FRC dives and empty lungs dives are an excellent way to train many aspects of a deep dive, while staying in shallow water. Indeed, by exhaling some air before starting a dive, your lungs reach their residual volume much faster. You will be able to experience lungs and chest compression, practice your position and relaxation during your freefall, and work on your equalization skills, all the while staying at shallower depths. By simulating everything that happens during a deep dive, exhale dives allow freedivers to get the body and mind used to the pressure and to all physical changes. Because such dives are done on shallow depths, it is taking the mental pressure off, and allowing the diver to focus only on technique and sensations, and it also means that we can repeat several dives within one single session, which is not possible when doing deep full-lung dives. Note that such dives are advanced techniques and it is recommended to try them first under the supervision of a qualified instructor. Always pay attention to your sensations during such dives, and if you are not relaxed, or experience discomfort or difficulty to equalize, never ever push.
Freediving in general is a sport that relies a lot on mental strength. Deep diving requires a strong, confident, yet relaxed, focused, and quiet mind. These qualities can be practiced in many ways, without having to go for deep dives. Visualization is an extremely powerful tool, which is used by most top athletes in every kind of sport. The mind is an amazingly complex machine, but it is also quite stupid in a way, as it tends to believe everything you tell it! It cannot really distinguish between something that has been visualized, and something that has really happened: for example, it has been shown that people with injuries, bed-ridden for a while, recover quicker and have less muscle loss if they visualize themselves running or exercising. In freediving, it is the same: visualization of yourself doing a deep dive is a very powerful tool to prepare yourself for the real deal. There are many types of visualizations, such as very long ones where you go into all the details, or «real-time» visualizations trying to be as close to your real dive-time as possible, or problem-solving visualizations, where you prepare yourself for how to react to anything that might occur during an actual dive. In any case, the name of the game is to try to make it as realistic as possible for your brain, so involve all your senses, try to imagine it as if you were there!
Static is a great tool to get your body used to higher CO2 and possibly lower O2 levels. Training static will also increase your confidence: if you know that you can hold your breath for 5 or 6 mins, then a 2-min deep dive seems like a piece of cake! Finally, it is also a very good opportunity to work on conscious relaxation of both body and mind: you will then reproduce this more easily during your freefall for example.
These exercises can be done in shallow water, between 20 and 30 meters, to work on mental resilience and confidence at depth. The aim is to make the total dive time as long as possible. Going down as slow as possible, focusing only on complete relaxation, and staying at depth, then coming back up very slowly as well. For an even more challenging alternative, go down to 5 or 10 meters, hang there until the first urge to breathe, then go down slowly to the bottom of the rope (maximum 20 to 30m) and back up. These exercises increase your strength of mind and your confidence at depth, so you can stay relaxed even if you experience urges to breathe during a deep dive. These can lead to hypoxic territory, so they should of course be done with an experienced buddy, and you should progress very slowly. Beware also of the risk of DCS.
As in any sport, you need a good base preparation of the muscles. Aerobic training to work on cardiovascular fitness and VO2 max, and anaerobic training to get your muscles used to high CO2 and lactic contents, are exercises that can easily be done dry or in the pool and are perfect for preparation during the low season.
As you can see, it's still possible to train year-round for depth even when living far away from the sea or with access only to shallow depth, you can still find ways to keep your mind and body adapted. By regularly training your flexibility, equalization skills, mental confidence, and muscle strength, when you finally get access to depth, your return to your best deep diving will be that much smoother, easier, and faster. So there you go, now you have no excuse!