The body undulation and dolphin kick are at the core of the butterfly stroke. It is difficult to swim butterfly well if you haven’t mastered the body undulation first. But once you have mastered it, adding the arm movements is trivial by comparison. So this article proposes a few swimming drills to learn the body undulation and dolphin kick.

Swimmer practicing the wave-like movements of the butterfly stroke under water

Practicing the body undulation underwater helps develop a feel for its movements

Undulation Technique

Here’s how the body undulation and dolphin kick are executed in these drills:

  1. You lie flat on your stomach in the water, the head in line with the body and the face looking down.
  2. The legs and feet are kept together, the feet are pointed.
  3. You press the chest down in the water, then release it.
  4. As you release the chest, you press the hips down synchronously, then release them.
  5. As you release the hips, you start again to press the chest down, and so on.
  6. When the hips go down, the legs should simply follow along, with the knees slightly bent.
  7. When the hips go up, the legs again follow along, the knees extend and at this moment you can add some force and execute the kick.

Drills and Exercises

The drills below teach you the body undulation in a progressive manner. That’s why it is best to practice them in the proposed order. At first, practice the following drills using swimming fins:

Drill #1: At the water surface, lie on your stomach, face down, extend your arms in front of you, and hold a kick board. Execute the hip up and down motion as described above, and let the legs follow along and kick with your feet and fins. Do some body undulations and kicks, then stop to breathe, and start again.

Drill #2: Underwater, lie on your stomach, face down, keep the arms at your sides, then execute the body undulation and kicking motion. Stop regularly to breathe.

Drill #3: At the water surface, lie on your stomach, face down, keep the arms at your sides, then execute the body undulation and kicking motion. Stop regularly to breathe. This is the head-lead body dolphin drill.

Drill #4: Underwater, lie on your stomach, face down, extend the arms in front of you, then execute the body undulation and kicking motion. Stop regularly to breathe.

Drill #5: At the water surface, lie on your stomach, face down, extend the arms in front of you, then execute the body undulation and kicking motion. Stop regularly to breathe.

Once you have mastered the previous set of drills, proceed with the drills below:

Drills #6-9: Repeat drills #2-5 but this time without using fins. This most likely will be rather difficult, as you relied much on the fins for propulsion. It should help a little bit that you start again with an underwater drill, as you then have the resistance of the water both on your back and on your chest to push against. Take your time to master the drills without fins. Instead of directly going from with fins to without fins, you can also try to use shorter ones for a while or trim your regular ones progressively.

Drill #10: At the water surface, lie on your stomach, face down, keep the arms at your sides, then execute the body undulation and kicking motion. Each 3-5 cycles, press your chest and hips harder so that your head lifts above the water. Inhale quickly, then bring you head and chest back down and continue the body undulations.

Drill #11: At the water surface, lie on your stomach, face down, extend the arms in front of you, then execute the body undulation and kicking motion. Each 3-5 cycles, press your chest and hips harder so that your head lifts above the water. Inhale quickly, then bring you head and chest back down and continue the body undulations.

So that’s it, these are the 11 drills to learn the body undulation and dolphin kick!

Some Tips

Please take care of the following points while learning the body undulation and dolphin kick:

  • Some people have it easier to learn the dolphin kick and body undulation than others, and it seems that girls learn this motion faster than boys.
  • Avoid jutting your head, it should simply follow your chest up and down.
  • For the drills at the surface, avoid going too deep down in the water when pressing the chest. It should move about 5 inches up and down. If it moves more, you will also need more work to come back up. You should only skim the water surface.
  • Without fins, the drills where the arms are kept to the side of the body are much harder than the ones where the arms are extended in front of you. This is normal as there is less leverage to execute the body undulation when the arms are kept to the sides.
  • In the beginning, don’t add too much force in the kick. Remember, it’s the body that drives the legs, and not the other way around.
  • Later on, when you have mastered the technique, you can add more force to the hip movement and to the kick. The legs will then snap like a whip.
  • If your ankles are inflexible and you can’t point the feet and toes away from the body, use swimming fins more often. Using them will force your ankles to stretch and become more flexible over time.
  • When you start to integrate the breathing into the drills, avoid lifting the head up too much, as this will cause your hips to drop deeper and it will be harder to bring them back up. Just clear the head enough out of the water to allow a quick inhale. Keep the head aligned with the torso, you should be looking down to the water surface about two meters (6 feet) in front of you.
  • Always exhale in the water.
  • You may start to notice an underwater wave that brushes your knees while doing the dolphin kick. This is a good sign and means that you do the motion correctly.

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