Freediving / Apnea
The Sport of Breath-Hold Diving. All aspects of my journey into freediving including static apnea, dynamic apnea, constant ballast, training techniques, equipment and competition. Also includes a short freediving video. What does it feel like to be a freediver and breath holding underwater? Information about heart rate and holding breath.
|Calvin swimming back up after reaching 100ft deep for the 1st time.|
I just recently discovered the amazing world of freediving. Freediving is the sport of breath-hold diving. Having spent many years SCUBA diving and performing many other water-sports, I have always had an affinity for the water. Snorkeling was always very enjoyable, but my ability to stay down with the sealife was limited. Unlike SCUBA diving, freediving allows one an experience unencumbered by equipment, noise and bubbles. It is a very rewarding experience.
In February of 2004, I started a 12-week training program with Performance Freediving (run by Kirk Krack). It has completely opened up a new world to me. Now, after having completed most of the training, I am doing my ocean dives, and I can finally appreciate how effective this course has been. Prior to this year, I had probably never swum below 20ft while holding my breath. I would have never thought that I could ever swim down over 100ft on a single breath of air. With adequate training, it is within reach and can be done safely.
An important part of the training is in invoking the mammalian dive reflex, one that every human inherited from their evolutionary ancestors. This reflex allows one to significantly lower their heart rate (bradycardia), shift their blood flow to the core (blood shunt) and even reduce lung compression effects at great depths (thoracic filling). In addition, the training emphasizes significant physical, physiological and psychological tolerance as well as physical conditioning.
While recreational freediving is very exciting, it can also be a dangerous sport if one does not have proper training. The Performance Freediving course made safety a huge consideration, and I could never imagine doing it without this background. And, of course, never freedive alone!
Living in Canada, I have had the fortunate opportunity to train with numerous accomplished freedive women and men.
Current personal bests:
(progress only shown to 02/05)
|Static Apnea (Dry)
Breath-hold on land.
|6 minutes 01 seconds||04/13/2004|
|Static Apnea (Wet)
Breath-hold in water.
5 minutes 16 seconds
|Dynamic Apnea with Fins
Horizontal underwater distance in one breath.
|374 ft / 114 m DQ
336 ft / 102 m
|Dynamic Apnea without Fins
Horizontal underwater distance in one breath without fins.
|200 ft / 61 m||02/27/2005|
Swimming down to a maximum depth and back in one breath.
|136 ft / 41.5 m (depth)||04/24/2004|
|Static Apnea (Wet)||4 minutes 33 seconds||04/29/2004|
See my Freediving Photo Album! (includes pictures from the Western Regional Competition)
World Record Ranking
The current world rankings for breath hold (static), depth (constant) and distance (dynamic) for 2004.
What does it feel like to hold your breath / static apnea?
The following describes the type of sensations I'll get during a five and a half minute competition breath-hold / static apnea. Please note that this is in a competition or training environment and is not something I would do regularly for fun. As described below, the feelings can be quite unpleasant at times, but during competitions one must endure some degree of discomfort to approach one's safe physiological limit. The following is done in water under absolutely strict supervision by a number of trained safety spotters.
DISCLAIMER: Do not attempt breath-holds in water unless you are thoroughly trained in all of the safety issues and have a safety diver with you. A number of divers have died because of a lack of adequate training and safety support. Never ever dive without a trained buddy.
- One Minute - Very relaxed, not even really aware of holding my breath. Eyes closed to avoid thinking about being under water. Laying face-down, flat on the water, arms and legs dangling relaxed.
- Two Minutes - Occasional thoughts come to mind of the fact that I'm holding my breath, but these are easy to put aside for now. I start consciously trying to steer my mind away from these thoughts by running through the events of a previous day.
- Two Minutes Thirty Seconds - An internal pressure in my body starts to well up, and I know that I will be getting contractions soon. My body tenses a bit as I try to delay the onset of diaphragmatic contractions. Ignore the sensation of wanting to swallow as I usually feel some saliva in my mouth, as otherwise I end up swallowing air into my stomach, which obviously doesn't help oxygen exchange.
- Three Minutes - The internal pressure sensation reaches a level where it feels as though I am spending too much energy trying to delay the contractions. So I give in, allowing the contractions of the diaphragm to start. The discomfort of knowing that the contractions are about to start is similar to the feeling of knowing that you're going to be sick. The first contraction in my diaphragm causes my body to involuntarily spasm, as the body attempts to start its own respiration. The contractions are about once every ten seconds at first. A small wave of relief washes over me as I allow the first contraction to occur. I am very careful not to think about the time now, because otherwise I will end up comparing when my contractions started this time to when they usually start. There is nothing more demotivating than knowing that they started early this time. I have to consciously relax my body, especially my head and neck. Heart rate has begun to slow down.
- Three Minutes Thirty Seconds - The start of the hardest phase for me. This is where negative thoughts will continuously push into my mind. Bad thoughts flood in: "I don't think I can do it today", "today is the day when I'm going to give up early", "why am I doing this?" or "the contractions came on early this time". The physical sensations are intensely unpleasant, and it is hard to push on knowing that you can simply bring your head up to bail out. The body sensations are extremely strong, and at times it feels as though I must be drowning. Knowing that I'll spend the next two minutes in this state can be tough -- some people start their contractions much later and only need to endure a minute of contractions. For me, I usually end up with nearly three minutes of contractions. I continuously try to fill my mind with thoughts of the days past activities, constantly focusing on details. I don't want the negative thoughts to take over.
- Four Minutes Thirty Seconds - The turning point. By now, once I've gotten the signal that I've made it to around four and a half minutes, I start to feel happier. I know that I'm on my way to making five minutes, and the end is in sight. The contractions are every couple seconds and I am just starting to get used them. Occasional negative thoughts come in, but the feeling of knowing that five minutes is near is usually enough to put them out. Heart rate is dropping to less than 50 beats per minute (BPM). Need to open my eyes now, to make sure I'm aware of what's going on and can watch for signs that I am closer to my limit.
- Five Minutes - Beginning to get euphoric. I've made it -- its downhill from here. The contractions occur rapidly (about every second), and they are smaller. Negative thoughts are completely gone. I can hear my pulse clearly in my head and other sounds become muffled or distant. Eyes wide open, trying to stay alert. Hands on the deck, getting ready to come up.
- Five Minutes Thirty Seconds- Point of no return. Time begins to fly. It seems as though the callouts for the time are coming fast. I am no longer having any difficulty holding my breath. I watch for the signs that I'm nearing my limit: sounds become muffled, the beginnings of tunnel-vision and a feeling of it being easy. The hypoxic euphoria has a hold on me now and I must come up, otherwise it's easy to convince myself that I can go on further because I'm feeling good. Bringing my feet underneath me, I gradually turn my body upright and lift my head out. Six big recovery breaths, an OK signal and a smile for the judges.
Doesn't holding your breath kill brain cells?
Under construction Why this is a myth and why your brain is not without oxygen.
I participated in a study by researcher Dr. Andrew Blaber which attempted to examine the effects of breath-holds on the brain, amongst other things. An ultrasound measurement was performed on my head to evaluate the changes in blood stroke volume throughout the breath-hold. In addition to the cerebral blood flow measurement, various other readings were taken, including arterial oxygen saturation levels as well as pulse rate, blood pressure and end-tidal carbon-dioxide concentration.
One of the effects that he was interested in seeing was how the quantity of oxygen to the brain changed over time. Because of the body's mammalian responses, the blood flow through the body is diverted and concentrated in the core regions at the expense of the peripheral limbs. This, combined with a reduction in oxygen consumption, actually allows oxygen delivery to the brain to be maintained through the entire breath hold. At the end of my 5:43 breath-hold in the lab, oxygen saturation was still at healthy levels, showing that at no point in time was the brain "starved" for oxygen.
The current consensus seems to support the notion that brain damage only occurs in periods of about four minutes after blackout. This is the fundamental misunderstanding people have about freediving, and it explains why one will hear that you will die after being under water for four minutes. If you drowned and blacked-out in water, you may sustain brain damage within four minutes. But in a freediving context, one is fully conscious and the natural dive responses keep oxygen saturation levels high for long periods of time before any chance of blackout.
9 Minute Breath-holds without Breathe-up?
For an interesting article by Peter Scott on his interpretation of how these maximum holds may work, have a look at the lengthy thread here.
Safety support required in freediving
Under construction Various types:
- Static Apnea -
- Dynamic Apnea -
- Constant Ballast -
Body responses to freediving
- Bradycardia - Lowering of heart rate. In some trained divers, the heart rate can drop to five beats per minute on a deep dive.
- Peripheral vasoconstriction. The body shunts blood away from the periphery and redistributes the blood flow to the vital organs including the heart, lungs and brain.
- Reduction of oxygen consumption.
- Blood shift / thoracic filling . On deeper dives, the body shifts blood flow to the chest cavity between the diaphragm and the neck to avoid the collapse of the lungs under high external pressures. Eventually, blood plasma fills the lungs so that it is no longer compressible from outside pressures. Scientists originally proclaimed that a human could not survive a breath-hold dive to 50 meters as the lungs would compress to an absolute minimum volume before they would collapse under the outside pressure. The thoracic filling, along with significant trained flexibility in one's chest cavity, allows one to reach depths far in excess of what originally seemed impossible. Seals actually exhale before they start a dive, allowing these effects to be triggered much sooner.
- Facial sensors respond to cold water.
Techniques used by freedivers to enhance their ability:
- Facial immersion. Chemoreceptors in the face (near the nose) recognize cold water. Freedivers will try to immerse their faces in cold water before or during a static breath-hold.
- Negative pressure dives. Training to increase flexibility in chest cavity.
Sambas and blackouts
Laryngospasm. One of the most interesting safety mechanisms that the human body contains in the context of diving is the laryngospasm. If someone were to ever blackout under water, the detection of water entering the airways causes the larynx (vocal cords) to immediately close up, preventing water from entering the lungs (and causing a drowning). This sealing of the throat is what actually allows people to blackout underwater without suffering serious side-effects. The laryngospasm usually lasts for a period of a minute or so,
My current training progress online at Current Training Records
The following graph shows how bradycardia (slowing of the heart rate) kicks in during a dry static breath-hold. An interesting thing to note is that after the break of apnea (at 5:30), the heart rate jumps (due to the recovery breathing), but then falls back to a rate (44 BPM) lower than during the hold. My resting rate is typically 55 BPM. Prior to the breath-hold, my heart rate was about 70, but then the 8 purging breaths brought that up into the high 70s. Note that during deep ocean dives (where the full effects of the mammalian dive response can be triggered), the heart rate slows much further than on a dry land breath-hold.
My extreme sports video with clips of freediving
A very inspirational video of Benjamin Franz that I think shows what freediving is all about (hosted by Freediver.co.uk)
Equipment in freediving is much less involved than in SCUBA diving, which makes for part of its appeal. However, since it is vital that one must be very aware of their body and physiology, the equipment we do carry must be carefully selected.
Specialfins Freediving Monofin Carbon
A monofin provides much more efficiency than a standard bifin. One of the main differences being the surface area and to a lesser degree not as much non-laminar (turbulent) flow past the fin. With bifins, the water that is squeezed between the pair of fins (during a scissor kick) creates significant turbulence, inducing drag.
Although I didn't find that many difficulties using my plastic bifins down to 40m, I had understood from many other divers that the "lack of power" at the deep turning point was a concern with the bifins. Thus many deeper divers often migrate towards the monofin.Comments:
I have just started training with my new carbon fibre monofin and I must say it has been an interesting learning experience! So far, I have only used it in the pool, but I definitely feel that this is a big improvement over my "fibreplastic" bifins. Unfortunately, I still feel that I must look like an injured dolphin, floundering around! I am going to need quite a few training sessions before I feel comfortable going for a target dive.
Cressi Sub Gara 2000 LD
Long-blade fins take time getting used to, but they allow for much better propulsion, while sacrificing maneuverability. Many freedivers' fins are carbon fibre, but until my legs are more accustomed to the extra effort, I will stick with the plastic fins.Comments:
The Gara 2000 LDs feel very comfortable, and are not as stiff as the 2000 HFs. The drawback I see at this stage with them is that they have fairly flexible footpockets, which may contribute to the occasional foot cramps I get.
Ultra-low volume mask. Unlike in SCUBA diving where one typically uses a large mask with a wide field of view, in freediving it is essential to have a low-volume mask. This is particularly important when one starts going deep. The reason for this is that one must equalize the mask at depth (60-80ft +). If one is at 100ft below (4 atmospheres of pressure), the volume required to equalize the mask, multiplied by 4 gives you the volume of air required from the lungs/mouth (at the surface). Since the air in your mouth & lungs are vital for duration and middle-ear equalization, one must conserve every bit.
Similarly, once I start to return to the surface and reach around 40ft or so, I will breathe back in the air from my mask so that I can utilize it without wasting it (otherwise it would bubble out of the mask).Comments:
So far, I have been very pleased with the Samurai. It has a moderately low volume (middle of the line) and decent field of view. Comfort is very good, and I haven't had any problems with it so far. Another mask that is very popular is the Technisub Sphera; offering a wider field of view and lower (76mL) volume.
Read an article on how to measure freediving mask volume.
| Dive Computer:
A dive computer is essential for freediving. Not only does it give you an accurate depth reading (along with audible warnings so that you know that you've reached your target), it can record your entire dive's profile into memory with a 1 second sample rate. This allows one to review the dive afterwards and determine appropriate corrections for technique.Suggestions for the D3:
Keeping your body in a state for freediving involves eliminating any other physical or psychological factors that could reduce your performance. Shivering, or being worried about the cold will reduce your focus.
A 5.5mm freediving wetsuit is typically much warmer than a standard wetsuit. Waterflow through the suit is nearly eliminated, partly due to the dense closed-cell neoprene.
Bare 3mm Cold Water Gloves
Gloves are essential for keeping your hands warm. It is important to have a pair that will still retain enough dexterity to hold the line, change settings on your dive computer and potentially adjust your gear during a dive. Like most of the freediving equipment, waterflow must be reduced as much as possible.
MEC Neo Paddling Socks
Booties not only insulate your foot from the cold, they also provide some degree of fit improvement for your fin footpockets. One consideration is how much the booties will compress at depth. If your fit becomes too loose, a set of Fin Keepers are recommended.
| Weight Belt:
Picasso Rubber Belt
The typical goal is to weight oneself so that you are neutrally-bouyant at 10-15m. This helps provide some margin in recovery in case of SWB.
The weight belt material itself is actually quite important. When one is at a depth of 100ft, your lungs have compressed to a quarter of their original volume. Similarly, the bubbles in the neoprene suit have also compressed. The net effect of this is that the belt diameter set at the surface will no longer fit snugly at depth. In fact, it will fall down your torso towards your shoulders. Having a belt made of elastic rubber will allow the belt to stretch smaller at depth.
Currently, I wear 10lbs for ocean Constant Ballast diving (with wetsuit, which sets me neutral at about 15m) and 4lbs for pool Dynamic Apnea training (without wetsuit). In the future, I may try 12lbs so that I can be neutral closer to 10m.
One of the more limiting factors to depth progress can be equalization (ears and mask). It is important that there is some water against the outside of your ear, not just air on the inside of your wetsuit hood. Having some water will remove another potential airspace that could create a vacuum effect that could make equalization harder. However, having cold water from the outside coming in contact with your eardrum can cause other discomfort. So, putting cotton balls in the ears helps reduce these issues.
One way around the vacuum effect problem is to punch a small hole through the wetsuit hood in the region of your ear. This will allow a small degree of waterflow. I am going to try sticking with flushing the hood with water first before I cut any holes.
Although I have no need for this so far, it is possible that fishing line or other entanglements exist in some areas of the ocean. Having a means to quickly cut the line is crucial. I think it makes perfect sense to have some safety backup in this way.
Tolerance Training (CO2, O2 Tables)
Download the graphical tables for (by Mozzi) (2331 downloads)
Original tables and background material.
Links of Interest
- Dive Geek's Bibliography
- A large bibliography of material on breath-hold diving
- Collection of answers to medical questions people had about diving (SCUBA & breath-hold).
- Duke University
- AIDA Brasil Articles
- Freediving & decompression sickness.
- Ama diver neurological incidents.
- NCBI PubMed
- NCBI PubMed. Free access to millions of medical abstracts.
- Pulmonary Physiology
- Michael Levitzky. Sixth Edition. 2003.
- Respiratory Physiology: The Essentials
- John B. West. 2000.
- Exercise Physiology.
- Scott Powers, Edward Howley. 3rd edition.
Personal Sites & Photo/Video Albums
- Eric Fattah's Freediving
- Local diver - Eric Fattah
- Andrew Brownsword
- Local diver - Andrew Brownsword
- Tom Lightfoot
- Local diver - Tom Lightfoot
- Mandy-Rae Cruickshank
- Local diver - Mandy-Rae Cruickshank
- Tyler Zetterstrom
- Local diver - Tyler Zetterstrom. Writings and photos.
- Umberto Pelizzari Gallery: Dolphins
- Umberto Pelizzari. Swimming with the dolphins.
- Benjamin Franz
- Benjamin Franz.
- Tanya Streeter
- Tanya Streeter
- Audrey Mestre
- Audrey Mestre
- Freeology Profiles
- Profiles of several well-known freedivers.
- Deeper Blue Productions
- Some great photos of the freediving masters.
- Freedive Vancouver
- Freedive Vancouver
- Performance Freediving
- Performance Freediving Clinics (Kirk Krack). Home of an excellent freediving school.
- CAFA - Canadian Association of Freediving and Apnea
- CAFA : Canadian Assocations of Freediving & Apnea
- Freedive Sweden
- Freedive Sweden. A collection of training tips and records.
- Suunto Dive D3 Demo Software
- Demo of the Suunto D3 model.
- Suunto Dive Manager Software
- Suunto Dive Manager software 1.51.
- Suunto to Clie
- Creating an interface for the Suunto line for the Sony Clie PDA.
- Suunto interface schematics
- Many different schematics for building a Suunto PC interface, instead of spending $200.
- Freediver reviews of Fins
- Extensive user comparison between freediving fins.
- Spearsniper's Equipment overview
- Overview of freediving / spearfishing equipment. Equipment Vendors: Dive Computers
- Very popular Suunto dive computers, including the Freediver D3 and Mosquito. Equipment Vendors: Monofins
- Specialfins / Sebakfins
- Excellent fiberglass & carbon fibre monos, bifins.
- WaterWay Canada
- Popular fiberglass & carbon fibre monos, bifins. Reasonably inexpensive.
- Monofins & bifins Equipment Vendors: Miscellaneous
- Spare Air
- Spare Air. A tiny SCUBA system capable of 48-85L.
Training, Techniques & Articles
- Gerald Schmidt's Freediving Training
- An excellent summary of various freediving-related techniques.
- Eric Fattah's Equalization
- Eric Fattah's highly respected training article on Frenzel equalization techniques.
- Freediving Norway
- Sebastian's Norway freediving website. Excellent source of information and data collected from his own experiments.
- About.com: Interview with Streeter
- An interview with Tanya Streeter on everything about freediving.