The Science and Art of the Monofin: Theo-Patrick Fourcade on Elite Technique
From biomechanics and mobility to rhythm, equipment, and repetition, one of monofin swimming’s most experienced coaches breaks down what truly makes the technique work.
This interview originally appeared in Pillar Three of The Depth Collector Book One, the section dedicated to technical mastery. I am republishing it here as part of Depth Talks, a series of conversations with freedivers, coaches, and ocean people whose experience shaped the way I think about training, performance, and depth.
Witnessing a true monofin specialist in action always leaves me in awe. When the technique is right, the movement looks almost effortless. But behind that apparent simplicity is an extraordinary amount of mobility, coordination, body control, and technical precision.
I believe monofin swimming is one of the most difficult freediving techniques to truly master. The blade is incredibly powerful, which means poor technique can sometimes be hidden behind sheer propulsion. But when technique, mobility, rhythm, and power finally come together, the result is beautiful.
I had the privilege of meeting Theo-Patrick Fourcade during one of his visits to Taiwan. I was riding around Xiaoliuqiu on my old, rusted scooter when I suddenly spotted him sitting in a coffee shop.
Patrick has an impressive résumé. He is a World Champion in finswimming speed apnea, a former World Record holder, and a 17-time French National Record holder. He has coached some of the best freedivers in Asia and has shared his extensive knowledge of monofin swimming through the AIDA Monofin Swimming series. He is also the founder of Be Water Freediving and Be Water Factory, where he designs and builds high-end monofins.
Despite his demanding schedule, he generously took the time to answer all my questions.
So, without further ado, let’s dive into the fascinating world of modern competitive mermaids and mermen with one of the most experienced monofin coaches in freediving.
Understanding The Science and Art of the Monofin
What is the principle of the monofin swimming technique?
Theo: To put it succinctly, monofin swimming has two distinct movements. There is what I call the downward movement, pressing down on the water with the monofin, and the upward movement, repositioning yourself so you can press down on the water again.
These two movements make up one swimming cycle.
The ideal technique involves positioning yourself so that you can take advantage of the support created by the fin against the water while projecting yourself forward hydrodynamically, and then efficiently repositioning yourself to repeat the cycle.
Describing and explaining monofin technique is a very broad subject, and I try to cover it in the three manuals of the AIDA Monofin series: AIDA Monofin Freediver, AIDA Advanced Monofin Freediver, and AIDA Master Monofin Freediver.
The Body Behind the Technique
Which muscles play a pivotal role during a CWT dive? Are there any particular exercises you would recommend to strengthen these specific muscles?
Theo: If we consider that there are specific muscles involved in CWT, then they are the muscles engaged during the longest periods of effort in the dive: the freefall and the ascent.
Even though these two parts of the dive are different, the muscles used during the ascent also play a role during freefall.
The common element is alignment.
During freefall, you want to remain passively aligned so you can take advantage of hydrodynamics. During the ascent, you want to maintain dynamic alignment so the force produced by the monofin against the water can propagate efficiently through the body in the direction of movement.
The muscle groups responsible for passive alignment during freefall and dynamic alignment during the ascent are similar to those used during planks or weightlifting exercises such as deadlifts, clean and jerks, and power cleans.
These are global movements that create connections, synchronization, and coordination between muscle groups.
For planks, pay attention to your alignment, whether facing the floor or working from the side. Do not hold the position so long that fatigue causes your alignment to collapse.
You can begin with static work and then make it dynamic by introducing small movements that force the core to resist deformation.
For bar exercises, work with a stick or an empty bar. Instead of trying to lift heavy weights to impress others, increase the number of repetitions without weight. Think of it as an endurance exercise where fatigue comes from repeatedly executing a good movement rather than from lifting something heavy.
You should aim to build long, flexible muscles rather than short, rounded ones.
Long and flexible muscles provide a greater range of motion over a longer period and are more resistant to prolonged, repetitive effort, like the continuous swimming cycles of monofin swimming.
Stretching is therefore essential. You can work on individual muscles or more globally on the entire anterior muscular chain.
If you already have heavily developed muscles, flexibility should come before additional strengthening for monofin swimming.
In that situation, weightlifting may not be the priority apart from core work. Your priority may instead be loosening the shoulders through repeated arm movements in freestyle and backstroke swimming, for example.
Pool vs. Depth
The techniques for pool swimming and open-ocean diving can vary quite a bit. Could you clarify the differences and nuances between these disciplines?
Theo: Comparing pool and sea means comparing performance in a closed, stable environment with performance in an open, unstable one.
In a pool or pit, almost everything is known: the water temperature, the markings on the bottom, the absence of current, and the overall environment.
The athlete can focus almost entirely on performance.
In an open environment, there are uncontrollable parameters such as sun, wind, temperature, current, and depth. These force the athlete to adapt mentally and technically.
Because the constraints are different, the swimming technique must also adapt.
The disciplines themselves impose different demands. In the pool, the objective is to swim the greatest possible distance. In the sea, the objective is to dive as deep as possible.
The basic monofin movement remains the same, but the strategy and technical details change.
This is why it is essential first to understand and master the fundamentals of monofin technique. Only then can you adapt those fundamentals to the specific discipline.
Specializing in DYN or CWT helps you understand the constraints of each discipline and how the technique needs to change.
For example, in the pool, your technique may involve a kick-and-glide strategy: one or more swimming cycles followed by a gliding phase.
During a CWT ascent, that is impossible.
If you stop swimming, you descend again as if the depth is pulling you back down. So the ascent requires continuous propulsion, and therefore the strategy is completely different.
Proprioception is also different. Swimming horizontally in DYN does not feel the same as swimming vertically in CWT.
Being able to reproduce vertically what you have learned horizontally, while managing entirely different constraints, requires very accurate body awareness.
Technical mistakes also have different consequences.
Bending the knees in front of the pelvis during DYN may simply indicate limited ankle mobility and might not have a major consequence.
Doing the same thing during a deep CWT ascent can be catastrophic. It creates huge energy expenditure, makes the ascent much harder, and can jeopardize the entire dive.
Amplitude, Rhythm, and Speed
Could you shed light on the debate between large and small amplitude kicks in monofin swimming? What are the advantages and disadvantages of each?
Theo: These are not really different techniques. They are different swimming strategies.
Speed in the water depends on the relationship between amplitude and frequency.
So you have to find the right compromise depending on the speed you want to achieve.
Swimming slowly allows you to take more time and push against a larger volume of water with greater amplitude.
Swimming fast requires a higher frequency.
If you swim with high frequency, you do not have enough time to push against a large volume of water. If you swim with very large amplitude, each cycle takes more time, which limits your maximum speed.
So, depending on your abilities and your strategy, you adapt the technique.
Turning Efficiently
Based on your experience, what is the most effective turning technique in a pool with a monofin?
Theo: In finswimming, the tumble turn is the best turn.
In dynamic apnea, I prefer the turn where you push off the wall because I have a certain relationship with speed that mentally does not allow me to waste time doing a scorpion, or butterfly, turn.
I think a finswimmer would generally prefer the same kind of turn.
A freediver who is willing to spend more time underwater during the performance may choose the scorpion turn.
Technically, I do not really like the scorpion turn because it is relatively slow to execute and requires a stopping phase to bring the arms forward.
If I had to use this turn, I would work on a method that avoided ending up with my arms along my body immediately after the turn.
The Technical Mistakes That Cost Energy
What are the most common mistakes you encounter among beginners and even experienced freedivers? Are there usual mistakes that seem to prevail?
Theo: Most inexperienced swimmers do not see all the nuances of swimming technique because they do not have access to a club or coach who can guide them in the right direction.
But there are also freedivers who perform very well despite having technique that could be significantly improved.
In DYN, many are not aware of the role that different swimming cycles can play before the gliding phase.
In CWT, some athletes develop cognitive biases that create significant technical flaws.
One example is ignoring the balancing role of the arms and keeping them completely immobile during the ascent.
This is a technical mistake because it creates major repositioning problems and leads to inefficient swimming that can exhaust the athlete before they reach the surface.
We often see divers with limited flexibility trying to maintain an arm position above the head during a CWT dive. In your opinion, would it be more advantageous for those with limited shoulder mobility to keep their arms along their bodies?
Theo: If a swimmer wants to perform and is able to hold the correct arm position for a while, but then the shoulders cramp and they move their arms alongside the body, I get angry.
It is unacceptable to dive deep if the technique cannot be maintained throughout the dive.
In that case, the depth has to adapt to the athlete’s technical mastery.
If I cannot maintain proper swimming technique for more than 20 meters of ascent, then I should not dive deeper than 20 meters.
At some point, if you want to master swimming technique, you have to work on it.
You cannot say you are working on monofin technique because you swim 40 meters to reach the dive site and then perform five dives.
Technique requires repetition. Daily, regular work.
You need to work on flexibility in the pool. You can mobilize the shoulder joint through freestyle, for example, and gradually develop the correct arm position through specific exercises.
You have to be willing to work on the technique and dive according to the level of technical mastery you actually have.
Why am I so strict about this?
Because during a CWT dive, you have to ascend.
To ascend, you have to work the monofin effectively, and you need to reposition it correctly.
Without the help of the arms, repositioning becomes much more difficult and the dive becomes longer.
The arms play a major role in monofin technique.
If you do not know how to use them, you make the dive harder.
Instead of thinking, as you read this, that you can already dive deep despite imperfect technique, think about what you could do if you truly mastered it.
I know what you could do.
Much better.
Shoulder Mobility and Arm Position
Regarding the shoulders, which seem to play an important role in monofin swimming, could you share your favorite exercises or routines to improve shoulder flexibility?
Theo: Shoulder flexibility is developed more effectively at first through mobilization rather than by forcing stretches that place excessive stress on the tendons.
It is also important to avoid shortening the shoulder muscles through bodybuilding exercises that create excessive muscular hypertrophy.
Pilates can be very useful, especially when combined with breathing work that helps isolate the muscles involved in maintaining the arm position.
Pool training focused on arm position, which we call the triangle block, can also help.
Use specific exercises over short distances, around 15 to 25 meters maximum, with plenty of recovery.
This allows you to gradually learn the correct position.
Essentially, the scapular belt pushes the arms forward. Your back rounds, and your arms sit around ear level.
Don't pull the fingers forward.
The fingers stay relaxed.
Choosing Your First Monofin
Choosing the right equipment can be a challenge, especially for beginners. What advice would you give to those buying their first monofin? Is it necessary to invest in top-of-the-line equipment right from the start, or is it acceptable for beginners to start with a more basic model?
Theo: Start with simple, effective, reasonably priced equipment.
There are three main types of monofins: fiberglass with a flat foot pocket, fiberglass with an angled foot pocket, and carbon with an angled foot pocket.
If you are a beginner and buy a carbon monofin right away, I think that is a very poor choice.
Carbon is expensive and does not age particularly well.
My advice is to first buy a fiberglass monofin with a flat foot pocket and learn the technique in the pool.
This will also force you to work effectively on ankle flexibility.
Later, move to a fiberglass monofin with an angled foot pocket. At that point, the work you have done to develop a beautiful glide will begin to pay off.
A carbon monofin becomes a reasonable purchase when you have become a strong athlete with excellent technical mastery.
Ideally, that monofin would mainly be used for competition.
Carbon and epoxy resin age together, and with continued use the blade gradually loses mechanical efficiency.
Technique Before Performance
Given the unique physical demands of monofin swimming, do you recommend a particular conditioning routine before diving into intensive monofin practice?
Theo: The first task is learning the technique without chasing performance.
That should already be part of your normal training routine.
Every day when I swim, I repeat the same technical exercises to improve or maintain my swimming style.
It is a little like martial arts, although I do not practice them, or playing the piano.
Every day, you begin again with the same scales.
Technical learning in monofin swimming is neither magical nor mysterious.
Once you understand the theory and practice the exercises correctly and regularly, you will become a good monofin swimmer capable of moving with elegance and efficiency.
Following a training program designed only to improve physiology without working on technique is a poor choice.
You will never progress as much as you could by simply improving your swimming technique.
Learning From the Best
From your point of view, who would be the best freediver in terms of mastering monofin technique?
Theo: We are talking about technical mastery of swimming, not performance.
Even so, I will not publicly say who I think is the best.
I tend to notice technical flaws first, and those flaws appear quickly when athletes get tired, even when their performances are impressive.
I am probably not very good at answering this question because even among some of the best athletes in the world, I still see things that could be improved.
And there is another important point.
The best athletes cannot always be used as models to copy.
They often have particular physical characteristics or abilities that we do not possess, and those characteristics allow them to swim successfully in a certain way.
Work with your own abilities.
Start from your own blank page and build from your own strengths.
That is the best way to progress.
Train, Train, Train
As an expert in finswimming, do you have any key tips or words of wisdom for someone new to monofin swimming?
Theo: Train, train, train.
Connect with Theo
If you want to take your monofin technique further, discover and/or master the Science and Art of the Monofin. Theo-Patrick Fourcade offers coaching, training camps, masterclasses, AIDA monofin training, video analysis, online sessions, and personalized training programs for both developing and high-level freedivers.
You can explore his coaching, technical articles, courses, and monofin projects through Bewater Freediving.
Visit Bewater Freediving: https://bewaterfreediving.com
Further Reading
If you want to go deeper into freediving technique, movement efficiency, hydrodynamics, freefall, and the small details that make a dive cleaner and more economical, have a look at my book The Perfect Dive: Freediving Technique, Hydrodynamics, and Movement Efficiency.
It is about learning to waste less, move better, and understand exactly where efficiency is won or lost during a dive.
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