The Final Frontier II: Secrets to a Faster Dolphin Kick

The Final Frontier II: Secrets to a Faster Dolphin Kick

Developing a fast dolphin kick is not easy, yet everyone can improve their dolphin kick speed with the right anatomical tools and training. The motions involving the articulation of the back, hip, knees and ankles are all critical to a fast dolphin kick. Further, leg strength and stamina are essential.

Perhaps the most important anatomical feature of a fast dolphin kick is plantar flexibility of the ankles; the ability to point the toes inward. This ability enables the swimmer to create more propulsion on the down kick with the same amount of effort as a swimmer with less flexibility in the ankles. It allows the swimmer to achieve that propulsion with less knee bend. Bending the knee less results in less frontal drag, less deceleration, and the ability to maintain a higher speed.

While a strong propulsive down kick is a vital part of a fast dolphin, the real x-factor in the dolphin kick is with the weaker up kick. A good dolphin kicker will generate propulsion on both the up and down kicks. Using the Velocity Meter, we have analyzed many dolphin kickers and have found that weak kickers generate very little, if any, propulsion during the up kick. Olympian Kelsi Worrell accelerates up to 4.6 m/sec2 during the dolphin up kick, increasing her speed by .3 m/sec or more. While that may not be as much as the 9-11 m/sec2 that she accelerates from the down kick, it is vitally important in maintaining a higher average speed.

Further, as a result of her forceful up kick, she creates a stronger vortex that increases the propulsion from her following down kick. Kicking forcefully in both directions tends to help each kick, while kicking hard in one direction only tends to weaken each kick. Fast kickers learn to use their vortices better by kicking hard in both directions. Using the technology from the Ben Hur, which measures frontal drag at a speed of 2m/sec, we also found that by using a stronger up kick, the frontal drag force was 4% less than when using a strong down kick technique; yet another reason to use a stronger up kick.

However, there is more to this story. While dolphin kicking on the stomach, the propulsion comes at the very beginning of the up and down kicks. There are also two key peak deceleration points that occur in each kicking cycle. One occurs at the end of the down kick, when the feet begin to relax and hang toward the bottom of the pool. The other is when the legs elevate past the horizontal position on the way up to prepare for the next down kick. With most poor kickers, because of the extra knee bend required to generate propulsion, the deceleration from the legs drawing upward and forward is far greater than that from the feet hanging down. With Kelsi, she actually decelerates more at the end of the down kick than she does at the end of the up kick. Part of that is due to less of a need to bend the knees, but she has also learned to snap the beginning of the kick in both directions, and then back off of the leg accelerator from that moment on. She also drops the knees slightly during the up kick in order to keep a lower drag coefficient. All of these techniques lead to a faster kick with a more constant speed.

Here are some good tips on developing a better dolphin kick, a.k.a. the fifth stroke:

  • Increase plantar ankle flexibility with stretching exercises
  • Dolphin kick on your side with fins pushing hard in both directions
  • Snap the beginning of the kick, but lay off the speed of the legs after that, keeping the kick tighter and narrower while still undulating your hips
  • Emphasize the beginning of the up kick more than usual
  • Practice lots of dolphin kicking on your stomach, side, back, vertically or horizontally. You can’t get faster without practice

Be sure to check out Olympic swimmer Roland Schoeman demonstrating several ways to improve your dolphin kick in our three part swimisode series on the fifth stroke.

Yours in swimming,

Gary Sr.

One Response to The Final Frontier II: Secrets to a Faster Dolphin Kick

  1. Ike Kanu

    Dear Gary,

    Thank you for the sharing these details about kicking.

    Please, some more guidance on flutter kicking mechanics in isolation (i.e., using a kickboard/snorkel in stream mode) vs. in-coordination with the arms in full (freestyle) swim mode.

    It appears to me that improving kick time in isolation mode doesn’t necessary translate to a [proportional] drop in time when swimming in full swim mode (with the arms in sync). Sometimes the kick/arm coordination seems to be the real problem.

    How does one get to improve the kick/arm coordination for bettter swim time?

    In terms of gym equipment, what do you recommend best for targeting legs muscles for stronger kicks?


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