dolphin kick

The core movement of butterfly is a body dolphin. You initiate it by pressing your chest into the water and then letting the water push it back up again (sort of like a spring), and then let the ripple travel all the way down your body to your feet. When it gets to your feet, it will drive your feet down in a dolphin kick. You should keep your chin loose while you're doing this, and as you push down with your chest, you should feel like it's driving the top of your forehead toward the far wall. It is often easier to get the feel for this movement if you do it while wearing fins.

Originally posted by LindsayNB it seems to me that the underwater dolphin kicking one does off the wall is different from the full body dolphin motion one does during full stroke butterfly. Watching underwater dolphin kicking at the start and turns it is pretty clear it is not initiated at the shoulder or chest. The frequency of the off the wall dolphin kick is also far higher than one could possibly using during surface butterfly. I agree. When I'm dolphin kicking after a start or turn, I think about moving my belly button up and down instead of pressing my chest. I am also not comfortable with an explanation of dolphin kicking that can only apply to one-kick butterfly. In a two kick style the upper body and lower body are moving with two different frequencies. Not only that, but if you watch a one kick style swimmer like Thorpe or Esposito the timing of the kick does not fit the wave moving down the body model. When I observe underwater butterfly video I see a downward movement of the chest and legs which raises the hips. This is common to one kick or two kick butterfly, the basic difference between the two is that in one kick style the swimmer simply drags their body and legs during the pull while the two kick swimmer does a dolphin kick during the pull. It is this second kick which follows the moving wave model. There is more than one two-kick style, but the most common that I've seen in recent years alternates a small kick with a grand kick. The grand kick is the one that arises out of the body dolphin. I actually believe that the function of the small kick may be to help get the ankles and feet back up to the surface, since the water obviously isn't going to push them back up, as it does with your chest. The other thing I find problematic with the snake moving through the water analogy is the inability of the human lower body to bend in both directions (i.e. the knees only bend in one direction). Obviously, the legs are not going to perfectly "snake".

There are a number of aspects of the dolphin kick that I'm still unsettled about. Firstly, it seems to me that the underwater dolphin kicking one does off the wall is different from the full body dolphin motion one does during full stroke butterfly. Watching underwater dolphin kicking at the start and turns it is pretty clear it is not initiated at the shoulder or chest. The frequency of the off the wall dolphin kick is also far higher than one could possibly using during surface butterfly. I can't remember the exact source but I am sure I've read that the actual transmission of force via a wave down the body is very small, unlike a wave moving down a towel as you whip it your body is moving through water where the resistance forces are much larger. It seems to me that it would be more accurate to describe the wave motion as following an arc that minimizes resistance than to describe it as a propolsive movement driving the legs. I am also not comfortable with an explanation of dolphin kicking that can only apply to one-kick butterfly. In a two kick style the upper body and lower body are moving with two different frequencies. Not only that, but if you watch a one kick style swimmer like Thorpe or Esposito the timing of the kick does not fit the wave moving down the body model. When I observe underwater butterfly video I see a downward movement of the chest and legs which raises the hips. This is common to one kick or two kick butterfly, the basic difference between the two is that in one kick style the swimmer simply drags their body and legs during the pull while the two kick swimmer does a dolphin kick during the pull. It is this second kick which follows the moving wave model. The other thing I find problematic with the snake moving through the water analogy is the inability of the human lower body to bend in both directions (i.e. the knees only bend in one direction).

One of the frustrations of talking about butterfly kick is lack of a clear consistant terminology for the two kicks. The only clear way I can think of to differentiate the two kicks is the one that occurs approximately as the hands are entering the water and the one that occurs approximate as the hands leave the water. I'll call these the hand entry kick and the hand exit kick. Talking about big kicks and small kicks can be problematic because in the hand entry kick the kick completes with the body in a piked position while at the end of the hand exit kick the body is in a straight line. If you watch Phelps the two kicks are pretty much equal although the hand entry kick appears larger because of the piked body position. The kick that flows out of the body undulation is the hand exit kick which is the kick that single kick butterfliers do not do (in reality they do a sort of half kick). Here are images of Phelps as he finishes the hand entry and hand exit kicks, note that the depth of the kick is the same in both cases.

Does anyone know any drills to master that kick?I am having a lot of trouble doing it during starts and turns, my body does not seem to move the right way.What part of the body initiates the kick, what do you need to focus on moving a certain way when doing it? Thanks.

I am not that great at underwater dolphin kicking but I did improve somewhat by spending some time just swimming back and forth across the pool underwater. At the start I couldn't make it across the pool but after going back and forth for twenty minutes I could make it the width of the pool easily. Sometimes it is just a matter of persistance and experimenting to see what works and what doesn't. One of my biggest problems is lack of flexibility I have difficulty undulating in a tight streamline position so I have to trade off between streamlining and kicking effectively. I hope that with enough stretching I can improve on this. One point to remember is that the size of your kick should vary inversely with your speed. When you first come off the wall you and are travelling at high speed a large undulation and kick will just slow you down, start with very small very rapid kicks and build the amplitude as you slow down to swimming speed.

Does it make sense to do some dolphin kick with fins too? Does that make the muscles involved stronger? Does the corresponding faster speed help to feel the drag so you can improve the streamline? Thoughts on this anyone?

I have a pretty good dolphin kick on my back. In the mid-80s I had the privilege to work out in the same group as Pablo Morales. One of the things I've never forgotten, that Mitch Ivey taught us about Pablo's kick, is that he always kicks up and down with his feet. Whenever I kick dolphin kick on my back I press the top of my feet up towards the surface, which is the easy part, but I always remember to push the bottoms of my feet down as well. Of course that's a pretty small detail when you're trying to figure out what the rest of your body should be doing in relation to your legs! I just thought I'd throw it out. Hope it helps. :)