Frog kick efficiency

[dmaziuk]

What are the less damaging stretches?

It went very silent after you posted that picture @dmaziuk … I can only guess everyone in this thread is trying to recover after trying that pose

Well... I just found out I can't fully touch my butt to the floor anymore... but I have not been stretching much lately. As in: the last decade or so.

Seriously, though, this is bad because it drops your body weight on the joints -- hips mostly -- twisted way out of shape. It's not nearly as bad when you do it for the breaststroke kick with no dead weight on the joints. Still, "breaststroke knee" is a thing just like tennis elbow.

Anything that stretches leg joints: taichi, yoga, etc., is good, but there is genetics involved too: apparently some people have deeper hip sockets than others, and some people have the bone there angled slightly differently, so... some hips just can't do that. Says google so it must be true.

 

[BlueTrin]

Well... I just found out I can't fully touch my butt to the floor anymore... but I have not been stretching much lately. As in: the last decade or so.

Seriously, though, this is bad because it drops your body weight on the joints -- hips mostly -- twisted way out of shape. It's not nearly as bad when you do it for the breaststroke kick with no dead weight on the joints. Still, "breaststroke knee" is a thing just like tennis elbow.

Anything that stretches leg joints: taichi, yoga, etc., is good, but there is genetics involved too: apparently some people have deeper hip sockets than others, and some people have the bone there angled slightly differently, so... some hips just can't do that. Says google so it must be true.

I think I am maybe missing flexibility in the ankle, I can get really close to the floor and I don’t feel any tension in my legs but if I go lower I’ll fall backwards: probably missing ankle flexibility to bring my legs more forward …

 

[dmaziuk]

I think I am maybe missing flexibility in the ankle, I can get really close to the floor and I don’t feel any tension in my legs but if I go lower I’ll fall backwards: probably missing ankle flexibility to bring my legs more forward …

I guess lack of ankle flexibility would affect the modified frog as well as the full breaststroke kick. If you can get in the pool with a kickboard and shorter swim fins, you could try laying on your back w/ your head on the kickboard, knees bent, feet doing ankle circles: basically the modified frog with just the ankles.

 

[ginti]

@Angelo Farina, it is always a pleasure to read your posts! Do you know if some scientific articles analyze the kicking efficiency at a large scale?

@BlueTrin, here you are a piece of my experience, but be aware that my case might be pretty different from yours (I have quite good flexibility and can almost do that pose in post #28).

POINT 1 - Air in your legs.

For me, the frog kick with some air in the legs is doable (but not efficient), while the back-kick becomes a nightmare. The best way is to avoid, in the first instance, having too much air in the legs. About this problem, your legs' position underwater might be a factor to consider.

If your position is like position 1, you may tend to accumulate more air in your legs than in position 2. I think this happened to me because if I stay in position 2, as soon as I have some gas in my legs, I feel they start floating, and I immediately dump air. By contrast, in position 1, I perceive the air too late because the gas will not make them move. Also, notice that position 2 is more efficient, giving less drag.

POINT 2 - Stability

When you kick, hydrodynamic forces will help you stabilize. If you are unstable but start kicking, you'll become more stable, but as soon as you lose velocity, the stabilizing effect of hydrodynamic forces disappears. Therefore it is almost an automatic reaction to kick again. In the past, it happened to me, and I first had to find a more stable neutral position.

I am not saying that you are surely unstable, but since you mentioned that you tend to turn a bit and compensate with your lungs, this might be a factor. I would try to move the weights or play with your arms' position (or even legs) to find more stability; then, I would try the frog kick to see if something changed.

 

[Angelo Farina]

@Angelo Farina, it is always a pleasure to read your posts! Do you know if some scientific articles analyze the kicking efficiency at a large scale?

@BlueTrin, here you are a piece of my experience, but be aware that my case might be pretty different from yours (I have quite good flexibility and can almost do that pose in post #28).

POINT 1 - Air in your legs.

For me, the frog kick with some air in the legs is doable (but not efficient), while the back-kick becomes a nightmare. The best way is to avoid, in the first instance, having too much air in the legs. About this problem, your legs' position underwater might be a factor to consider.

View attachment 774362

If your position is like position 1, you may tend to accumulate more air in your legs than in position 2. I think this happened to me because if I stay in position 2, as soon as I have some gas in my legs, I feel they start floating, and I immediately dump air. By contrast, in position 1, I perceive the air too late because the gas will not make them move. Also, notice that position 2 is more efficient, giving less drag.

POINT 2 - Stability

When you kick, hydrodynamic forces will help you stabilize. If you are unstable but start kicking, you'll become more stable, but as soon as you lose velocity, the stabilizing effect of hydrodynamic forces disappears. Therefore it is almost an automatic reaction to kick again. In the past, it happened to me, and I first had to find a more stable neutral position.

I am not saying that you are surely unstable, but since you mentioned that you tend to turn a bit and compensate with your lungs, this might be a factor. I would try to move the weights or play with your arms' position (or even legs) to find more stability; then, I would try the frog kick to see if something changed.

Interesting. But you assume two things:
1) scuba diving
2) dry suit
My experience was teaching finned swimming, which means no scuba apparatus and no suit (wet or dry).

I never used a dry suit.
I never used frog kicking when scuba diving.
So I cannot comment on the issues you described, sorry...

Regarding scientific literature about kicking efficiency with different types of fins and kicking styles, there was a lot of research here in Italy in the eighties.
Luigi Ferraro, the inventor of the Pinocchio mask and of the Rondine fins, later left Cressi and founded his own company, Technisub, together with his friend J.Cousteau.
At Technisub headquarters in Genoa they hired a young engineer, named Gianni Beltrani.
They designed and built the first kicking robot and an annular test pool, which you can see here below, for testing fins with different kicking trajectories.
They published some papers and they got a number of patents.
I should search in my library for the proper references...

 

[BlueTrin]

@ginti I think you are right about the position 1, I am trying to change my position to be more like position 2. I can usually tell if I have too much air in my legs because I can feel more drag with the drysuit and it feels like the boots are more loose.

I’ll try to practice a bit more but now that I am back from holidays I will have to wait two weeks before an opportunity to practice this at the local lake …

 

[berndo]

I think I am maybe missing flexibility in the ankle, ...

Likely it's not your fexibility but poor technique. What you're discribing in the OP with the weak kick and short glide phase is very common.

 

[ginti]

Interesting. But you assume two things:
1) scuba diving
2) dry suit
My experience was teaching finned swimming, which means no scuba apparatus and no suit (wet or dry).

I never used a dry suit.
I never used frog kicking when scuba diving.
So I cannot comment on the issues you described, sorry...

Thanks anyway!

 

[ginti]

I can usually tell if I have too much air in my legs because I can feel more drag with the drysuit and it feels like the boots are more loose.

Well, depending on your sensitivity and drysuit, this might be too late or not... I simply cannot say it

 

[berndo]

If your position is like position 1, you may tend to accumulate more air in your legs than in position 2. I think this happened to me because if I stay in position 2, as soon as I have some gas in my legs, I feel they start floating, and I immediately dump air. By contrast, in position 1, I perceive the air too late because the gas will not make them move. Also, notice that position 2 is more efficient, giving less drag.

Meh, if there is too much air in the suit it's going into the legs eitherway. The instability is usually caused by too much gas in the suit and/or to much weight on the diver. When you only put enough gas into the suit so the undergarment can expand (which is how you're supposed to do it), there is no air moving about in the suit to begin with.

BTW, bluetrin, what did your instructor say about this? He should have been able to fix it or tell you what to practice.