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How To Apply Proper Monofin Technique In Freediving (+ Examples)
In my experience, too many divers push themselves to use a specific monofin technique just because it’s what they were taught or what’s ‘accepted’.
The ‘new school’ of monofin technique is to use an extremely small amplitude with a very high frequency.
Is this right for everyone? Probably not.
Here are some factors to consider when deciding on the right style of monofin technique for you:
- Fin stiffness: To swim at the same speed, stiffer fins will require a larger amplitude with a lower frequency compared to softer fins.
- Strength: Stronger divers will likely prefer, and be more efficient with, a larger amplitude (& stiffer fins) than weaker divers.
- Personality: Calmer divers will likely prefer a slower frequency than less calm divers.
- Proportions: Taller divers will naturally produce a larger amplitude than smaller divers.
- Dive profile (depth): Divers who set neutral buoyancy deeper will need a smaller amplitude to ascend than divers who set it shallower.
- Dive strategy (pool): Divers who have kick-kick-glide will need a larger amplitude than divers who kick constantly, to move at the same average speed.
Beyond these personal preferences, there’s ONE very big finning myth that’s preventing freedivers from developing the optimal monofinning technique – the myth of, don’t bend your knees!
To explain this, I will first highlight an article I wrote on how to apply the proper bi-finning technique freediving, which first discussed the myth of ‘no knee bend during bi-finning.’
In my experience, the no knee bend rule is entirely untrue, and trying to achieve this impossible myth leads many divers to use an incorrect, inefficient, and uncomfortable monofin (& bi-fin) technique, which may end up being a weak link in their diving.
When it comes to monofin technique, evidence shows that elite, pro level dolphin kickers bend their knees. They actually bend them quite a lot, since the only way to actually dolphin kick properly is to: Bend your knees!
A 2017 study found that elite finswimmers bend their knees to an average angle of 124.7 degrees, with min/max values of {119.3 & 130.1} degrees*.
“Knee bending angle during a kick was 124.7 ±5,41 deg” (Kunitson & Port)
This tells us that bending the knee is necessary, and the best monofin swimmers in the world are doing it.
And, while we’re looking at the world’s top dolphin kickers, let’s analyse Olympic medalist Ryan Lochte. In the swimming world, he is considered one of the best underwater dolphin-kickers in the back-stroke discipline, and can reach speeds over 2m/s… WITHOUT FINS!
Here is an image of him practising his technique. Helped by my hand-drawn arrows, can you see no knee bend? I don’t think so!
So right away, it’s 100% clear that if you try to dolphin-kick without bending your knees, you’re doing something completely wrong.
Of course, you need to learn how to bend them correctly, when to apply the bend, and how to analyse whether or not you're doing those things optimally.
So for the remainder of this article, I’m going to try and help you better understand the correct application of knee bend so that you can improve the quality and comfort of your monofin technique.
First, why do we need to bend our knees?
Well, unfortunately, we are human beings :(
We evolved for walking, running, jumping, and lifting things on dry land. This means that instead of a full-body spine (ending with a fin), we have legs with only 3 joints, that take up half our body. This means that our anatomy is ‘flawed’ when it comes to finning, dolphin-kicking in particular.
If you look at dolphins and whales, they can smoothly raise and lower their fins and flukes, flexing their posterior and anterior muscle chains that run along their full-body spine. We cannot do this.
To dolphin-kick, as humans, we need to create a wave-like motion through our whole body.
Like any wave, the motion starts at one end (our shoulders) and flows to the other (our feet). It’s also important to consider that the size (amplitude) of the wave will grow as it travels down our body.
The first half of this motion is quite smooth since it runs through our spine. However, once it gets to our legs, we need to apply correctly timed knee-bend to transmit and amplify the force down to our feet properly.
If you don’t bend your knees, you remove your leg muscles and reduce the final amplitude of the wave. Both of these things in combination can kill the kick, greatly reducing the power.
This will mean you have to kick harder from your upper body (more tension, contractions, risk of squeeze), and you’ll need to use a much larger range of motion in the upper body (again more tension, contractions, risk of a squeeze).
So in short: Not bending the knees kills the wave and forces you need to work much harder to produce the same power output and speed.
How to apply the correct knee bend to create a wave
To explain this, we need to break monofinning down into 2 separate parts; the front kick (fin moving in front of you) and the back kick (fin moving behind you). This will help us understand how the knee-bend is applied during the kick-cycle, and later it will help you perform your self-analysis.
To be completely honest.. Once you accept the need for knee-bend, understanding its use and application is relatively simple.
Step 1: During the front kick, you are going to extend your knees
This means moving them from a bent position into a straight position. This allows you to use your quadriceps to assist the motion created by your spinal erectors and hip flexors and push the fin, with adequate power, in front of you.
Step 2: During the back kick, you are going to bend your knees
This means moving them from a straight position into a bent one. This allows you to use your hamstrings to finish the motion created by your upper back and abdominals and ‘pull’ the fin behind you. It’s also essential to engage your calf muscles and keep your toes pointed.
As long as this is combined and correctly timed with the undulation (wave) of your spine, you will have an efficient and effective monofin/dolphin kick.
Now, let’s look at the front and back kick positions
To do this, I’m going to focus on Alexey Molchanov – since he probably has the best and most universal monofin technique in freediving.
No matter what your body-type, your equipment choice, or if you dive in the pool or depth, Alexey’s technique is applicable. Basically, if you’re doing things right, your technique should look very similar to Alexey’s.
In my experience, most divers who have major issues with their monofin technique have them in the back kick. So let’s start there.
As you can see, at the end of his back-kick, the point where the fin is as far behind him as it will get, there is a high degree of knee bend: 118 degrees on this particular kick.
I do believe freedivers can use slightly less knee-bend than fin swimmers since we require less power. This accounts for Alexey using 1deg less knee bend than the minimum seen in elite fin swimmers. **There also may be some measurement errors on my part, considering there's no ‘perfect camera angle’ that I can find of him in depth or pool.
Alexey produces a good amount of power from his back kick by achieving this correct amount of knee bend.
What’s very clear is that at the end of the back kick, the only ‘angle in the body’ is the knee-bend.
Knee-to-shoulder and knee-to-toe are two straight lines.
Now, he transitions to the front kick.
Since his knees are already bent, and the fin is ‘loaded’ behind him. All he needs to do is, extend his knees (straight legs) and contract his back muscles, arching his back and sticking out his bum.
At the end of the front kick (fin far in front) Alexey’s legs are perfectly straight, and there’s a slight curve from his hips to his shoulders. His back muscles contract, and his chest is slightly puffed out.
How to avoid the most common monofinning mistake
Very similar to ‘bicycle kicking’ with bi-fins, the most significant positioning mistake with the monofin causes you to push the fin into the water instead of back-and-forth through the water.
The incorrect position (shown below) is what I call the ‘chair’ position, and until last year, I was guilty of hitting the chair position regularly. You can see it clearly in my 2019 world championship dive.
This is a picture shows that at the end of my (old) back-kick, I would have two separate angles in my body;
-A bend in the knee (yellow lines)
-A bend in the hips (red line)
This mistake of pre-maturely bending at the hips ultimately kills the efficiency of the front-kick and removes the spinal erectors and hip-flexors as driving muscles, resulting in a quadricep-only (mostly) front-kick.
In my opinion, this mistake is the reason for the don’t bend the knee’s myth.
But as you see, this isn’t a knee-bend problem. It’s a hip-bend problem. The problem is that the hips are bending (bum sticks out) too early, almost at the end of the back kick instead of at the end of the front kick.
So, if you spot this ‘double angle’ in your finning, don’t worry about reducing knee-bend. Just make sure you work on starting the knee extension before arching your back and sticking your bum out.
How to analyse your monofin technique with a simple tool
So how can you analyse your own finning to improve your monofin technique, and what tool did I use to pause videos, draw arrows, and measure angles accurately for my distance coaching clients?
-Download the Kinovea app (Just FYI.. No, this is not a sponsored article & the app is free)
-With the help of an underwater camera, have your buddy film you either in the pool or in depth. Then upload into the Kinovea app will allow you to use a precision tool to pause the video at the right time, and with different tools, you’ll be able to measure angles and draw lines on your or your coaching clients’ body.
Like I said in the article, make sure to focus on, and analyse, your body position at the end(s) of your front and back kick and make sure you have the correct amount of knee bend. In most cases, if you get these end-positions right, you will end up finning with relatively high efficiency and proper form, and the rest of the kick-cycle will easily fall into place.
Then you can make small modifications based on your personal preferences, equipment choice, and general style. Remember, a smaller amplitude will require a slightly smaller knee-bend angle for the back kick, so pay attention to this when analysing your finning too.
Now go out there, start bending your knees on purpose, and fin with ease and efficiency!
Extra Reading: Finswimmer Study
*Analysis of swimming technique among elite finswimmers, conducted by VLADIMIR KUNITSON 1 , KRISTJAN PORT for School of Natural Sciences and Health, Tallinn University, Estonia
https://www.researchgate.net/publication/322606345_Analysis_of_swimming_technique_among_elite_finswimmers/link/5a672ae30f7e9b76ea8d6949/download
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