Discover why ankle strength, and not just flexibility, is key to a faster dolphin kick, and how this simple dryland tool can help power up your underwaters.
Dryland training is one of the most powerful ways swimmers can improve performance.
From strength training and stretching to plyometrics and core work, dryland gives swimmers the tools to generate more force, move more efficiently, and stay injury-free.
(When done right, obviously…)
But one of the most underrated—and essential—dryland tools for swimmers?
Jumping rope.
Why? Because it helps build stronger, more reactive ankles, a critical component a for faster, more powerful dolphin kick.
Why Ankle Strength Matters for Fast Underwater Dolphin Kicking
One of the first things the enterprising underwater dolphin kicker looks to improve is ankle flexibility. Which makes sense.
Ankle flexibility, more specifically plantar flexion and internal foot rotation, is crucial for fast dolphin kicking speeds.
But after a point, flexibility gains start to flatten out or the increased “looseness” doesn’t come with strength at range, limiting improvements in kick speed (Kuhn and Legerlotz, 2022).
That’s when ankle strength becomes the real game-changer.
A 2014 study by Willems et al. backs this up. The researchers found that stronger dorsal flexors (the muscles that pull the toes up) and internal rotators of the ankle (turning the feet inwards) were strongly linked with faster dolphin kick velocity in national-level swimmers.
Swimmers with stronger ankles literally kicked faster.
The Benefits of Strong Ankles for Dolphin Kicking
Here’s why having big, buff ankles helps swimmers dominate the underwater dolphin kick:
Stronger ankles withstand more torque
In an ideal world, you train your underwater dolphin kick with all the tools at your disposal, including resisted kicking, vertical kicking, kicking more, and so on. And with some hard work, your legs whip increasingly violently through the water.
The ankles are at the tail end of this kinetic chain and as a result, take on a lot of the strain and torque. Stronger ankles help to stabilize the joint so that you aren’t flopping the feet around at high velocities without the musculature to support it.
While most injury prevention in the water is focused on the shoulders, back, and knees, building up your ankles mean faster kicking and building the capacity to handle increased load and velocities.
Stronger ankles switch phases faster
Fast dolphin kicks fully utilize the propulsive effects of the downkick—it’s where a majority of our boom comes from when kicking. Which can give you high peak moments of dolphin kicking velocity.
But a truly fast dolphin kick is fast in every phase of the kick, and strong ankles help you to powerfully and cleanly transition from upkick to downkick (and back again). Fast transitions are also crucial for developing smoother undulation.
See also: 3 Reasons to Work the Upkick for a Faster Dolphin Kick
Reactive strength in the ankles helps you position the feet and ankles quickly so that you can build and maintain propulsion through the whole kick cycle and not just intermittently in the downkick.
Smoother kick transitions, faster kicking.
Stronger ankles = more force
The downkick is where the speed and power happen and it’s your ankles that are on the leading edge of delivering that force.
As the feet sweep downward, the feet push against the water, displacing it, and creating vortices to generate forward movement.
But if the ankles are weak or unstable, two not-great things happen:
- They lose their ability to maintain a pointed, streamlined position
- They can’t resist the reactive force of the water
This means less pressure is applied against the water and less energy is transferred into forward movement. Essentially, our feet are slicing through the water, not “catching” any of it.
Strong ankle muscles allow swimmers to maintain a forceful foot position under resistance, helping it catch and press against the water.
Jumping Rope – A Simple Tool for Stronger Ankles
Okay, got it: strong ankles = important and stuff for fast dolphin kicking.
Let’s get to the answer, and that’s jumping rope.
This simple, portable tool targets the stabilizer muscles in your feet and ankles, improves foot arch stiffness, develops reactive foot strength, and improves coordination and timing.
It’s also a great way to prepare your calves and ankles early in the season for higher intensity kicking sets later on.
The Bottom Line
Ankle flexibility will always be crucial for fast dolphin kicking. This is especially the case for swimmers with stiff ankles, who stand to benefit the most from the drag-reducing benefits of being able to point the toes in the water.
But ankle strength is where things can really start to improve in the water, particularly when you pair it with increase range of movement (e.g. building “strength at range”).
So:
Grab the skipping rope. Add several minutes to your dryland workouts or pre-workout activation. Strengthen those ankles. And drop the boom on your underwater dolphin kick.
The Ultimate Guide for a Faster Underwater Dolphin Kick
Want help leveling up your underwater dolphin kick? The Dolphin Kick Manual is the ultimate resource for helping swimmers and swim coaches develop a world-class underwater dolphin kick.
The Dolphin Kick Manual is a beastly 240+ pages of actionable insights and research into elite dolphin kicking technique and performance. It details everything from mastering undulation to vortex recapturing to structuring a dryland program for dolphin kicking success.
It combines evidence-based insights with a collection of 20 ready-to-go sets and a 6-week Action Plan to help swimmers set a course for dolphin kicking success.
Train smarter and kick faster.
