Monofin kick & glide for dynamics? | DeeperBlue.com Forums
  Guest viewing is limited
  • Welcome to the DeeperBlue.com Forums, the largest online community dedicated to Freediving, Scuba Diving and Spearfishing. To gain full access to the DeeperBlue.com Forums you must register for a free account. As a registered member you will be able to:

    • Join over 44,280+ fellow diving enthusiasts from around the world on this forum
    • Participate in and browse from over 516,210+ posts.
    • Communicate privately with other divers from around the world.
    • Post your own photos or view from 7,441+ user submitted images.
    • All this and much more...

    You can gain access to all this absolutely free when you register for an account, so sign up today!

Monofin kick & glide for dynamics?

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.

Pezman

We pee deep. Ew!
Sep 24, 2002
591
72
118
I recently tried a new technique for dynamics w/ my mono and had pretty good results. Basically, the technique that I tried was to make a few fast strokes and then glide. According to a several papers that I skimmed on the dynamics of swimming fish, optimal thrust requires that you maintain a certain ratio between speed, stroke frequency and stroke amplitude. As you go faster, the stroke amplitude must increase or the stroke frequency must increase (or both) in order to maintain optimal efficiency. My "theory" is that using a stroke and glide technique, you can get the optimal thrust efficiency and still keep the stroke frequency and amplitude within a range that human muscles can deliver. If you are constantly finning, you end up going faster and faster and the efficiency of the stroke inevitably declines because the strokes need to be imposibly fast and impossibly wide to provide optimal thrust. In addition, the water resistance goes up exponentially as you go faster (basically, you have to strike a balance between speed and the rate of oxygen consumption and going too fast causes the cost in terms of O2 consumption rate to exceed any benefit that you get from the greater speed).

On the other hand, I've never seen films of world-class dynamic swimmers using this kick & pause technique, so maybe it's not the best approach for some reason. According to the aforementioned papers, it is possible for an undulating body to generate drag below that of an equivalent rigid body if you move in the right way (Gray's paradox). Maybe that's why the "big boys" don't seem to do much gliding during monofin dynamics.

At any rate, if someone has the secret and is willing to share it ...
 

O'Boy

New Member
Aug 27, 2002
101
4
0
43
Kick and glide

I use that technique too, though mine is somewhat different.
After the start when I try to keep the 1 m/s pace I always use the prolonged gliding. I just bend the knees (90 deg.) and make powerfull kick with long and relaxed glide.
Then after some time (and distance about 75m) I just speed up with the classic finswimming undulating.
I need some 5 kicks for 25 mts.
 

Pezman

We pee deep. Ew!
Sep 24, 2002
591
72
118
Cool, how far are you going w/ that technique (sounds like at least 100m)
 

laminar

Well-Known Member
Aug 13, 2001
1,129
206
168
Hi Pezman,

It sounds like you know a lot about fish swimming mechanics (a lot more than me). I remember we were experimenting with different monofin strokes for constant weight, such as the kick and glide. It would be a great technique because you could make full use of anaerobic stored energy in the your kicking muscles.

The biggest factor against the kick and glide as you desribe it (with a 90 degree knee bend) is drag. Your knees and the monofin as you rechamber the "kick" will slow you down, required additional energy to accelerate you body from rest each time. Much less energy is required to keep you going at a constant speed, that probably why you don't see kick and glide at higher levels of competition.

If you had the core muscles of a fish or dolphin and the active streamlining strategies, then we wouldn't be having this discussion.

For me personally, the technique that works for dynamic is:
-minimal knee bend, full body undulation
-constant speed over 1 m/s
-arms overhead, relaxed, not in finswimmer's locked position
-soft monofin
-feel for the water (no suit) and my own version of "active streamlining" (far inferior to marine mammals, of course)
-a neck weight to add momentum
-sprinting at the end of the dynamic

But I haven't done a dynamic in ages.


Pete
Vancouver, BC
 
Last edited:

Sebastien

New Member
Jan 23, 2003
18
4
0
For me on the other hand I prefer to use a surfing technique: create your own wave and then surf it, i.e., wave motion. This requires power initiation from the core and moving the body as one single unit. Wave motion is the most effective form of motion when moving in a fluid medium.

Because of assymetry in the dorsal ventral plain throwing the arms out forward generates excessive tension in the back muscles which in turn reduces range of motion in the up stroke, which in turn reduces efficiency.

To reduce active drag slow the recovery phase (up stroke).
To reduce acceleration and hence energy cost aim for continuity. This also makes use of the body's natural elasticity.


Works for me!

Sebastien Murat
Townsville, Australia
 

laminar

Well-Known Member
Aug 13, 2001
1,129
206
168
Hi Sebastian,

Following the wave form sounds wonderful, I remember talking to you about it a while back, but I imagine it takes a lot of time to fine tune the technique, especially the angle of attack for the upper torso and head. Unfortunately, my work schedule and our local pools don't allow for that kind of tweaking. Someday very soon, I'll have my very own lake or ocean beach to spend each morning meditating on the best ways to move with the water.

I make do with a much more relaxed "arms over the head" profile that allows for better undulation on the upstroke vs. the traditional finswimming profile.

I've also been thinking of bodysurfing with bi-fins and a mono. I tried bodysurfing without fins, with a rapid undulation to catch the wave and it worked really well. I'm thinking that a large wave would chew up my mono--I'd probably need a much smaller fin, with vertical stabilizers for traction on the wave.

Anyone else have any experience with bodysurfing? (Waves bigger than 2m) It's a real rush and a natural extension of freediving (coming up into the wave from below, for example--yeehaa!!! :D )

Pete
Vancouver, BC
 

loopy

Deeper Blue Hypoxyphiliac
Oct 24, 2002
719
51
0
39
Hey Seb - 3 questions :)

First off, how big are your undulations to make the wave?

Second, I saw a vid of one of your dynamics, and it looked like you had your arms locked tightly next to your body, with your neck scrunched up and shoulders forward - is this position relaxed, or are you trying to minimise drag?

And finally, are you still planning on coming to Syd later on to do a VB? :D

Cheers once again,

Brad
 

cdavis

Well-Known Member
Jan 21, 2003
4,006
779
218
71
body surfing/freediving

Hi all

Never thought of body surfing as an extension of freediving but I sure love doing both. The adrenalin rush coming down the face of a big wave, shooting a big fish, or being seriously hassled by a shark (after its over) are all indescribably fabulous, near the ultimate in feeling totally alive. Some of the skills and the feeling of being one with the ocean are the same.

For me, in Florida, 2m waves are once or twice a year, if I am lucky, and then not much over 2m face. They also don't have the power of a pacific wave of the same height. No matter, even 1m are a lot of fun. There is one place in Florida that breaks 4m on sand, very, very rarely. One day I'll catch that one.

laminar, I'd love to see your "no fins" technique. Getting going fast enough to catch a 2m wave is quite an accomplishment.
 

Sebastien

New Member
Jan 23, 2003
18
4
0
Hi Brad

The amplitude varies with swimming speed. The water will 'tell' you what amplitude for the respective backward flow. To understand what its telling you you must be able to sense and understand the signs. Listen for noise (around your ears) and feel the turbulence on your skin.


The trick, at any speed is to be able to undulate or wave-ride such that the body, from head to trailing edge move as a single unit.

When moving from a stationary position speed is low which means that water moving past your body is also moving slowly. In other words, I don't have to undulate fast to catch and 'ride' my wave. As a result I kink my body a lot more at the various joints, thereby finding and catching 'new', flowless water and minimizing 'slip'. The head and trunk move considerably at such low and early speeds. Active drag, due to increases in amplitude (increased projected area) at low speeds is of minimal concern at this stage. If you've ever seen a dolphin accelerating from stop you'll know what I'm talking about.

As speed increases, however, active drag becomes a more important consideration consequently amplitude must be decreased as otherwise stroke length will be reduced significantly affecting both speed and O2 transport cost. In this stage the body moves even more as a single unit, like a like a flexing ruler, for example, no kinks at the joints. Just focusing on improving technique and automating it as much as possible I've found that I can now do, for example, as many as 50 x 50m (pool) passive exhalation with recently purchased 'Technisub ALA' fins in approx. 35-37" with 43-45" recoveries. I can assure you my specific fitness has not all of a sudden improved dramatically to be able to do that, but my technique has; previously my recoveries were in the order of 1'. It may seem like this is relatively fast but I can assure this is the most economical speed for me to swim at; anything less and I suffer dyspnea an excessive build-up of lactic acid which curtails the session short.


The shoulder forward and 'scrunched' neck could improve streamlining but this I believe is negated by the extra energy required to maintain shape; the reason is to throw my weight forward to couteract my naturally sinking legs. In other words I try to press on my lungs such that my center of gravity moves closer to my ceneter of buoyancy; this prevents imbalances and allows you to allocate more of your energy to propulsion rather than for correcting imbalances.

Sydney (Port Hacking):hmm. Based on access to charter boat and accommodation cost (AUS$20,000), it's becoming more and more of a distant prospect compared to either Greece or Bali. Ironically, we're getting more unsolicited support than here at home! My bet at this stage, on cost alone, is Bali, mid-year.


Sebastien
Townsville, Australia
 
  • Like
Reactions: Alun

efattah

Well-Known Member
Mar 2, 2001
3,294
487
173
I don't understand why reducing acceleration improves efficiency. Moving at a constant speed is not necessarily more efficient.

If you give yourself a burst of speed and then glide to a stop, you got back all the energy you put in, minus the drag energy you gave to the water. The drag energy you lose increases as the square of your speed, so having your speed oscillating about some set point (i.e. non-continuous velocity) might work in some conditions.

In fact, one might argue that if you only kick while your body is at rest, then the kick itself does not produce drag, only power. Then, during the glide, you can remain streamlined and motionless, with minimum drag.

Kicking while moving, however, always breaks your streamline, resulting in more drag.

So it seems non obvious that a constant speed would work best.


Eric Fattah
BC, Canada
 

loopy

Deeper Blue Hypoxyphiliac
Oct 24, 2002
719
51
0
39
Originally posted by Sebastien
Ironically, we're getting more unsolicited support than here at home! My bet at this stage, on cost alone, is Bali, mid-year.

You should've picked jervis bay - you could've all racked out in my folks back yard and taken dads tinny out... :D

Am I allowed to ask what depth you think you'll be aiming for? Is it going to be officially certified?

Eric: Which technique do you personally use? Glide or no glide?
 

derelictp

Freediver
Oct 16, 2001
397
63
118
53
I have tried different styles of swimming including the "kick and glide" ,arms stretched relaxed, arms stretched like a finswimmer.

This is a conclusion of what is working for me and not:

-Kick and glide produces lactid acid earlier compared to continous rythm. Not working good for me.
-Arms along the body is not working because my fin is to stiff. I will try this when I got a softer mono.
-Arms stretched relaxed makes to big drag for me but that may be because I am not so flexible in my shoulders.
-My current technique is the following. Arms streched very tight, 13-14 small amplitude strokes per 25m and speed around 1m/s. The upstroke is slightly slower than the downstroke and my knees is in a relaxed position. I increase the speed a little after around 75-85m.

Dynamic apnea is what I think very difficult and demands a lot of practice. One of my problems is that I don't wan't to wear a suit because of the lost flexibility and increased drag. I always freeze very fast which makes it even more difficult.:(
 

efattah

Well-Known Member
Mar 2, 2001
3,294
487
173
If kick & glide produces lactic acid earlier, that may be a good thing. The whole point in dynamic is to use all your free energy, meaning your legs should be jello at the end of the swim. If you didn't fail your legs, you didn't use your full anaerobic potential. If the acid bothers you, you could try working on your lactate threshold.

Eric Fattah
BC, Canada
 

derelictp

Freediver
Oct 16, 2001
397
63
118
53
Yes I was thinking that way too but in the end I'm in fact making better results with the method I described. It's not the lactid acid that bothers me, my belief is that it increase the demand for oxygen in the end of the swim.
(Most of my training is anaerobic, and with very much lactid acid tolerance sets)

My theory is that you make an "oxygen-debt" when you work anaerobically and in dynamic apnea (especially in the beginning of the swim). I belive that is negative when the work is over a certain time (>1.30-1.45, when the body says "-it's payback time dude").
The human is of nature more adapted to aerobic work than to anaerobic!?
(After the diving reflex has kicked in I think that the way we swim makes less difference because the body forces itself to slow down the metabolism. That's why I belive many divers benefit from speeding up at the end.)

Constant weight is in my opinion very different because I can relax on the descent and at depth the blood is out of the legs and I can benefit more from an anaerobic state. The "working time" in a constant weight dive to 75m is maybe around 1.15-1.25?

Maybe that's why many very good CW divers are not so good dynamic divers and the opposite?
The two disciplines probably demands a different way of diving.



Probably different divers will experience that my case is not the same as theirs because everybody is different.

The human body is a very very complex system and that's why I find it so interesting to explore this wonderful sport.:)

One thought that came up in my head:
A good way to simulate for example a 60m CW dive physically in pool would be to swim 25m, do a 1min static on the bottom and the swim 60m. That's probably the closest a CW dive one can get in pool?

By the way one of my buddies impressed me today by doing a 2.30 breathhold followed by a 100m dynamic. I'm happy if I manage 2min breathhold+75m dynamic.:head
 
Last edited:

Sebastien

New Member
Jan 23, 2003
18
4
0
True Eric, it's not obvious.

In my experience I've found that I can dive deeper and further if I swim continously. I tend to swim at a speed that permmits energy reduction by using stored elastic potential energy from antagonistic muscles.

I agree that the stroke and glide technique is energetically more efficient if your are a fish; fish have muscular symmetry side-to-side. But we are not dorso/ventrally symmetrical in terms of energy and power. This I think causes problems for us.





Seb
Australia

PS:
I'll only dive to the depth of my understanding and no more, Loopy. I think we'd have trouble getting dives certified since I'm not in the business of 'fetching' tags!
 

Sebastien

New Member
Jan 23, 2003
18
4
0
My last explanation bugged me a bit as it felt incomplete. I think I can draw out a better one.

It may pay to think of it in this way:
Let's say we should strive for an economically efficient transport cost with the fish ideal; the stroke-glide technique. As I mentioned prior that would be ok if we were symmetrically constructed dorso-ventrally but as were not our only alernative is to swim the up or back phase of the stroke as slowly as possible. This is where I 'catch' my wave. We can do this fairly well if we relax the lower legs and point the toes back such that the legs are straight. If we kink the joints in this phase we end up putting on the breaks. This is the best I think we can get to the glide phase with our peculiar anatomy, if our goal is to cover as much ground with minimum effort. Because our range of motion is severely resricted in this pahse there isn't much amplitude which would otherwise increase active drag.

On the down or forward part of the stroke joints can kink and so timing of the various segments so that they act in unison is important. In this phsae, the stroke phase, I 'ride' my wave feeling it pass under me unhindered. Failure to achieve this results in excessive drag, particularly around the lower thigh/ knee area. This is the phase we're you can really work the wave and get some reasonable range of motion but, its importnat not to over-kick it which could result in excessive active drag.

So, in short we can try to achieve the ideal stroke-and-glide model, albeit in an attenuated form; the stroke is a stroke but the glide is very much slowed movement to prepare for the next stroke.

Hope this clears things a bit.



Forgot to thank-you for the offer Loopy but we've already looked at Jervis Bay and we'd have to go some 20km out to make it worth our while.


Sebastien
Australia
 

loopy

Deeper Blue Hypoxyphiliac
Oct 24, 2002
719
51
0
39
Yeah, you're not wrong - we had to head out to the FAD (about 5 k's out) just to get more than 50m (there's a hole there that drops about 95m)... and last time we were out there, there was a big shape with a fin in the water... :D

Are there any specific exercises you've used to practice this technique, apart from just trial and error, and feeling the water?

Brad
 

Pezman

We pee deep. Ew!
Sep 24, 2002
591
72
118
Sebastien,

Thanks for the tips. I'm going to try to put some of this into practice next time I hit the pool.

Out of curiosity, which mono are you using. I have a Waterway LD-1 and since the fin is not angled, you need to glide w/ slightly bent knees (else you'll tilt down towards the pool bottom).

I did notice that Waterway has a new model with a winged leading edge and an angled blade (not that I'll be getting one anytime soon ;)).
 

Sebastien

New Member
Jan 23, 2003
18
4
0
I cannot understate enough the importance of focusing on technical development over fitness in a medium such as water. To develop fitness you'll need to fatigue yourself which will result in significant technical decrements and consequently, the rehearsal of incorrect movement patterns that become well ingrained.

If the technique is sound one can cover more ground per stroke and hold off muscular fatigue a little longer. If the strokes are fluid you'll also increase bottom time as well.

Perfect practice makes performance perfect.

It really is all about quality of feel and repetition. There is no easy way or short-cut; you've got to do the time, if not to better appreciate it and make it all worthwhile. In can take years an getting shipwrecked. Things happen quicker if you're process rather than goal oriented.

In my own training, I tend to work predominantly on technique. Fitness is something that develops by doing a lot of technique. If I can't visualize it, I rarely swim it! Also, I'll only swim for as long as I can keep it together.

I've noticed that by doing passive exhalation dives which don't result in excessive lactic acid or CO2, I'm able to exert myself closer to my maximum without compromising technical integrity too much. Fitness still improves because it places considerable hypoxic stress. Furthermore, recoveries can be fairly rapid which of course is important in a medium which can rob you of body heat very quickly if rests between repetitions have to be extended to vent off waste products.

If I'm looking to increase my anaerobic capacity then I'll likewise dive in the vertical dimension which is very specific.

Training with the mono I'll use a 'Waterway' Model 1. To redress the angle in the insteps try inverting your feet inwards. I use that for deep diving too. If your technique is sound and your stroke length is high than you can use fairly soft blades all the while conserving vital anaerobic energy stores.


I'll have to check-out the angled blade on their web...Thanks Pezman.


Sebastien
Australia
 

O'Boy

New Member
Aug 27, 2002
101
4
0
43
Kick & glide

I've done 100m+ with the undulating technique (something like Shinomya's 133m video) and now I'm trying this kick & glide technique. It's true that after the swim with this technique you get very acidic legs. The only help is to work on your anaerobic potential.
I've started to use this technique after my friend's recomendation. He was silver medallist in 1500m finswimming Junior world champs. Now, as a freediver newbie he is experimenting a lot on his freediving technique.
I've got classic WaterWay M1 LD but I'm about to order M1 MD.
I think that some stiffer blade will be much better for this kick & gliding.
I just love that feeling of relaxation while gliding. The only problem seems to be to get the blade up with the bending of knees. It's important to do it right in time.
I have my hands stretched over my head like finswimmers. The drag (and distance) you get in this position is just unbelievble. It's upon you to learn to relax in this position.
 
DeeperBlue.com - The Worlds Largest Community Dedicated To Freediving, Scuba Diving and Spearfishing

ABOUT US

ISSN 1469-865X | Copyright © 1996 - 2021 deeperblue.net limited.

DeeperBlue.com is the World's Largest Community dedicated to Freediving, Scuba Diving, Spearfishing and Diving Travel.

We've been dedicated to bringing you the freshest news, features and discussions from around the underwater world since 1996.

ADVERT