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    So you are interested in competitive freediving? Be sure to read out guide to Competitive Freediving first.

    One of our expert resident freediving instructors has outlined some advanced competitive freediving techniques below. Please keep in mind these are for advanced divers. If you would like to learn more, consider a freediving course or training group.

    What is FRC?

    FRC has become known more in its abbreviated form than the full words. The full term is: Functional Residual Capacity. This refers to the air that remains in the lungs after a passive exhale. When a freediver exhales in a relaxed fashion without any force, this is called a passive exhale. FRC is most often used as a training aid. With a low volume of air in the lungs at the beginning of a dive FRC simulates depth conditions without having to dive deep. For example a 15 metre dive could be equivalent to a 40 metre dive. Freedivers can practice their equalisation techniques without the risk and huge efforts of doing a deep dive.

    Diving with FRC is a way of training lung flexibility in preparation for deep dives. It takes good flexibility in the lungs and thorax to enable the diver to get deep. Deep dives done by an inflexible diver can result in a lung squeeze, or trachea squeeze. With FRC the freediver can train this flexibility without having to go deep.

    FRC has also been used to get the MDR kicked in earlier in training. Similarly, it has also been used by swimming coaches to simulate altitude training without having to move into the mountains. There is less oxygen in high altitude locations and training in such places increases the Haemoglobin in the athlete’s blood thus getting more oxygen out to the muscles needing it. FRC training does this.

    What are freediving tables?

    Freediving tables are a series of breath-holds or underwater swims put together to exercise and improve a diver’s abilities. The two usual types of tables are CO2 and O2 tables. Tables are usually used in static apnea and dynamic apnea but can be done in depth conditions.

    CO2 Tables

    The purpose of CO2 tables is to increase the diver’s tolerance to carbon dioxide. High CO2 levels in the body is the physical trigger that encourages a diver to breathe. However in freedivers the effect of high carbon dioxide usually comes well before there is a shortage of oxygen and in new divers will result in a shortened dive. CO2 does not just have physical effects, it is most often accompanied by changes in mental attitude. Divers surfacing due to the effects of high CO2 often report intense negative attitudes towards the dive/breath-hold, and even to the sport itself. It is a recognised effect that divers exit a training program at the point where they are working into the area of high CO2. There have been schools that taught hyperventilation in the early stages of training, to give the diver the satisfaction of completing a longer dive while still feeling comfortable, and without any negative mental effects. The liability of this, of course is that the diver will then have to unlearn the risky hyperventilation practices, and will still have to confront the discomfort etc. of high CO2 at some point.

    CO2 tables work by increasing the CO2 markably without allowing the O2 to severely depleted. This is done by doing a series of swims or breath-holds, with decreasing recovery times. A diver knows he is doing the CO2 tables correctly when he is experiencing the increased effects of hypercapnia.(high carbon dioxide) without approaching hypoxia (effects of low O2). The most noticeable effects are: The urge to breathe, lung contractions, negative reactions and feelings.

    This is an example of a simple CO2 table in static apnea:

    2 minute breath-hold, 2:00 minute recovery

    2 minute breath-hold, 1:30 minute recovery

    2 minute breath-hold, 1:00 minute recovery

    2 minute breath-hold, 0:30 seconds recovery

    2minute breath-hold, 0:15 seconds recovery

    2minute breath-hold.

    There are a myriad of different tables, both carbon dioxide and oxygen promoted on the internet and even apps to help regulate the exercise. If a diver knows the purpose of the table then he can adjust and run the table with correct intensity for his fitness and abilities.

    When a table goes down to its most intense point as the above example, but then cycles back up to the starting point, it is called a pyramid. A pyramid could look like this:

    2 minute breath-hold, 2:00 minute recovery

    2 minute breath-hold, 1:30 minute recovery

    2 minute breath-hold, 1:00 minute recovery

    2 minute breath-hold, 0:30 seconds recovery

    2minute breath-hold, 0:15 seconds recovery

    2minute breath-hold, 0:30 seconds recovery

    2 minute breath-hold, 1:00 minute recovery

    2 minute breath-hold, 1:30 minute recovery

    2minute breath-hold

    Here is an example of a simple CO2 table done in Dynamic Apnea:

    50 metre swim, 2 minute recovery

    50 metre swim, 1:30 recovery

    50 metre swim, 1:00 recovery

    50 metre swim, 0:30 recovery

    50 metre swim, 0:15 recovery.

    Oxygen Tables

    Where the CO2 tables work the diver in tolerating high levels of carbon dioxide, the purpose of oxygen tables is to bring the diver to tolerate and handle low levels of oxygen. In CO2 tables it is the recovery time that is restricted, but in O2 tables the breath-hold or the distance swum is increased without shortening the recovery time.

    Oxygen tables need to be worked with constant attention on keeping the gradient of increase within the capabilities of the diver. This is because you are working the actual cause of diver blackout, low oxygen. When working oxygen tables your aim is to keep within the diver’s ability and slowly increase this ability. As in all freediving training a blackout is a failure in working the correct gradient for that diver and should be avoided.

    Here is an example of a simple O2 table in Static Apnea:

    2 minute breath-hold, 2 minute recovery,

    3 minute breath-hold, 2 minute recovery,

    4 minute breath-hold, 2 minute recovery,

    5minute breath-hold.

    This table at a level for a more experienced freediver, but one just adjusts the times or distances swum to suit.

    Tables Tips

    1. When doing tables in the water, your buddy or a safety diver, must be present and attending the dive. In the pool, the same as in the ocean, no dive or breath hold should ever be done unwatched.
    2. Static Apnea tables can be done dry, for example on the couch at home. There are apps that work you through various tables. One would not need a safety diver or a coach when doing these drills dry as there is no chance of drowning.
    3. Both CO2 tables and O2 tables should be started at a point where they are not difficult and the intensity gradually increased. This allows the diver to increase his physical abilities, as well as work out mental attitudes and systems to get through the tables.
    4. In the pool the dive buddy can also monitor and call out the times for the diver. This allows the diver to focus on the breath-hold or swim and not get caught in any confusion as to recovery times etc.
    5. In training a diver will do the complete table under the watchful eye of his buddy, who calls out the times etc. Then they swap over and the the coach now becomes the diver and is coached through his complete table.
    6. CO2 tables should focus on raising the CO2 and the diver and coach should watch out if the diver becomes hypoxic. If the diver begins to exhibit signs of low oxygen, struggles to recover, overly blue lips, shaking and any other symptoms, the coach should either finish the table or if the symptoms are not severe, extend the recovery period before the next swim/breath-hold. The diver in this situation, must listen to the coach and act on the advice.
    7. A set of CO2 tables may increase a diver’s confidence and enable him to work through high carbon dioxide conditions, but generally one set of tables will not make a big change in a diver’s abilities, nor even a few tables. Tables should be regularly scheduled in a freediver’s training and done many times a year. This type of training will make stable changes in the diver’s abilities.

    What isPacking for freediving, and is it a good idea?

    Lung Packing is a system of manually forcing more air into the lungs after a full inhalation, through the use of the mouth, throat and tongue. It takes good coordination of the tongue and glottis to achieve this. When it is done it appears the diver is gulping air. The air is forced into the lungs through the pressure developed by using the tongue as a piston, by filling the mouth then forcing the air down the trachea. When the pressure is developed the glottis has to relax to allow the air into the lungs and then close when the pressure drops, trapping the added air in the lungs.

    Lung packing is a controversial subject with many opposing views and schools of thought. One freediving course provider bans it in their teachings and competitions and others just omit it from their course materials and give warnings about its practice. However, probably there has not been a world depth record achieved in the last 10 years by anunpacked diver and packing is practiced by the vast majority of competition freedivers. With very little connection between these two opposing views, there is no education or even guidelines on how a diver can safely learn this practice, and divers have to somehow make their own way if they want to use packing in their diving.

    A group of freedivers who regularly packed underwent a series of tests in a Sydney Hospital. These tests have been ongoing for over 10 years. The tests were not done primarily to support the diving community but the results have a great bearing upon freedivers. The initial tests were done to get more understanding about packing so it could be used by people who had lost the control of their lungs through a spinal injury but could still control the mouth and tongue. Through packing these individuals could be giving some freedom from their life preserving equipment. The doctors working on this area shared their data and even at times carried out tests at the freedivers’ requests to help sort out safe and unsafe practices. Many divers were tested, which included many different scans, before, during and after packing. Lung volume tests were also done regularly. One diver continued to be tested for over 10 years compiling a body of knowledge that included the benefits and liabilities of packing.

    Benefits of Lung Packing

    The major benefit of packing is in depth diving where freedivers can struggle with the equalisation of their ears through lack of air. Once a person has mastered the frenzal method of equalisation, so long as he has air in his mouth he can continue to equalise his ears. At some stage in a depth dive, which varies from individual to individual, the air volume in the diver’s lungs drops below residual volume. (residual volume: is the volume or air remaining in the lungs after a full and forced exhalation.) At that point the lungs will feel empty and the freediver will no longer be able to bring air from his lungs into his mouth to facilitate his equalisation. From then on the depth will be restricted by how deep he can equalise with only the air in his mouth. Packing will give the diver more air, and therefore in the final analysis, more depth.

    Packing does give the diver more air, and therefore more oxygen to complete a dive.

    There were some health benefits observed. One diver who was tested over the decade impressed the doctors. As he moved from his twenties through to his thirties he was told that his lungs were getting younger in their capacity and action.

    Mild packing and stretching has also shown to give greater lung capacity with no detrimental effects. The point beingmild packing. Extreme packing and negative or reverse packing has been blamed for injuries to divers. (negative or reverse packing is the practice of using the packing system of the mouth and tongue to take air out the lungs, used to create negative pressure by lowering the residual volume)

    What are the liabilities of packing?

    The tests showed there were some detrimental effects to packing. The increasing of the lung volume beyond the lungs natural boundaries caused the lungs to exert pressure on the heart. When divers were tested as they packed to their limits, the heart was observed to be pushed to one side and slightly twisted.

    Some divers, when packed tight, showed evidence of air escaping through the walls of their lungs into the body. This caused concern of the doctors, however, when they were tested a few minutes later, the escaped air had disappeared. One particular diver where this was quite evident has never experienced any trouble from this during his diving career of many years, which includes 100m CWT and plus 200m DYN.

    If you were to follow internet forum and facebook conversations many injuries and bad effects have been attributed to packing where there were no investigations. It is hard to pull apart the opinions from the facts and it doesn’t help that many of the opinions are expressed as facts. This demonstrates the real problem, lack of knowledge and reliable investigation. This is a major problem with freediving in general. It is a new era sport that doesn’t command enough athletes nor audience to merit the required funds to investigate it. However we have to conclude that injuries have occurred especially in any extreme use of packing.

    Packing also has the liability of seducing new divers to its practice rather than learning effective equalisation procedures. When such a diver achieves more depth through packing it can become that diver’s solution to all further gains. This is how one can be be lead down the path to injury.

    When a diver packs for a depth dive, at 10 metres all the air in his lungs is half the size bringing the lung volume down to below full capacity. As he further descends this volume decreases proportionately. This means the freediver has only about 10 - 15 seconds where the lungs are tight and exerting some pressure on the heart, after that the volume is below full capacity. However if the freediver packs full for a dynamic or static event, his lungs are tight and his heart is restricted through the entire duration of the event. It is logical that this condition should be avoided, especially with so little research done on the subject.


    Unless there are some major changes in the rules of competition freediving, to ban packing, this practice will continue. Such changes are very unlikely and would completely change the sport. All current and prior freediving records would become invalid to such new criteria. So how should a new freediver move forward on this subject.

    The best advice is to complete all the available freediving courses and become proficient at these skills through many hours of practice. This gives the freediver all the data to be able to make an informed decision and formulate his own goals.

    If the freediver intends to move into competition or deep freediving and wants to learn how to lung pack safely, rather than stumble through the mire of bad advice and trial and error, the freediver can find a mentor who has a good history of safe freediving and lack of injuries, who can coach him to this level. At this writing there is no official course or guidelines. This mentor/coach system is the only stepping stones available. In this age of litigation and blame, such a decision should be made only after much investigation by the athlete so that he can take full responsibility for this direction.