Ready to take your underwater dolphin kick to new levels? Here are some tips and ideas for faster underwaters.
No matter what your best stroke or favorite event is in the pool, fast underwaters are crucial.
Michael Phelps. Caeleb Dressel. Gretchen Walsh. Leon Marchand. Jordan Crooks.
These swimmers disappear under the surface of the water, clocking faster speeds than surface swimming, before exploding to the surface ahead of the competition.
With up to 60% (or 66% in the case of SCY) of races being swum underwater, it’s never been more crucial to fine-tune your underwaters.
In this guide, we will look at some proven ways to get more from your underwater dolphin kick.
By the end, you will have a clear idea of what to focus on when trying to improve the “fifth stroke” in the pool.
Let’s dive in.
How to Improve Underwater Dolphin Kick
Here is an overview of how to improve your underwater dolphin kick:
- Improve undulation
- Add resisted kicking
- Improve ankle flexibility
- Accelerate the upbeat phase
- Add Vertical kicking
- Use swim fins
- Add Monofin training
1. Improve undulation
A fast and smooth underwater kick relies on a wave-like motion that starts from the chest and whips out of your toes. This undulation is crucial for being able to kick fast and powerfully (Chen et al., 2022).
The thoracic spine—the middle part of your spine from the base of the neck to the bottom of the cage—facilitates the undulation for an effective dolphin kick.
Without it, the upper body is stiff and the dolphin kick starts from the hips, or worse, the knees, limiting undulation and velocity.
In a paper titled “Importance of Sagittal kick symmetry for underwater dolphin kick performance,” author Ryan Atkinson, Director of Performance Services at Canadian Sport Institute, member of Swimming Canada’s High-Performance program, and a biomechanist, observed that it “appears that upper thoracic flexibility is important for UDK performance.”
Swimmers can improve thoracic mobility and get more undulation and power from their kicks with several stretches that target the t-spine, including the Cat Cow Stretch, rolling on a foam roller (or Swiss ball), shoulder rolls, and improved posture.
One of the big challenges swimmers face with improving their underwaters is mastering the coordination and timing of optimal undulation. Increasing thoracic flexibility is a way to help swimmers dolphin kick efficiently.
2. Add resisted kicking
Resisted swimming, or in the case of improving underwater dolphin kicking speed, resisted kicking, is a proven way of helping swimmers improve dolphin kicking frequency and velocity.
In-water resistance tools such as DragSox, resistance tubing, and power towers create the conditions for “overstrength” training which can increase kicking velocity.
A study with elite Japanese swimmers (“Training to Enhance Underwater Dolphin Kick Speed in Elite Swimmers”) found that four months of supplemental dolphin kick training with resistance tubing significantly increased underwater kick velocity.
The intervention was as follows:
- Swimmers did 200m dolphin kick alternating 50m on the front, 50m on the back, focusing on undulation.
- They then strapped on a resistance tube (like StretchCordz) and did 5×5 kick cycles at full resistance with plenty of rest.
- The set was completed 3-4x per week during the course of the intervention, which lasted four months.
The results were significant: the men increased peak kicking velocity from 1.73m/s to 1.82m/s, and the women from 1.49m/s to 1.58m/s.
Those numbers may seem relatively small but consider that these were also very well-trained swimmers and elite dolphin kickers.
Grab yourself a shortened resistance tube—just a couple of meters—to ensure that you get to maximum resistance quickly for focused power development.
Add 4-5 rounds of 5-6 underwater dolphin kick cycles at full resistance, with lots of rest, and build more power and velocity in your kick.
3. Improve ankle flexibility.
Ankle range of movement is crucial for building a faster underwater dolphin kick.
When swimmers have flexible ankles, they “catch” more water, push the water behind them (instead of down), and reduce excess kick amplitude, which can generate added drag and resistance.
A study published in the Journal of Human Movement and Science (Willems et al, 2014) found that increased range of motion in the ankles corresponded with a faster underwater dolphin kick.
Another paper published in the Journal of Strength Conditioning Research (McCullough et al, 2009) also showed that ankle flexibility was a contributing factor to kicking speed with NCAA division I swimmers.
This should make intuitive sense: A flexible ankle gives swimmers more range of movement, allowing them to kick more water and generating faster toe speeds.
To improve ankle flexibility, consider adding ankle rockers, toe pointing exercises, and dynamic calf stretches with an angled board to your stretching and mobility routine.
4. Accelerate the upbeat phase.
The dolphin kick consists of two phases, the downbeat (or downkick), where a majority of the propulsion is generated in the kick, and the upbeat (or upkick), where swimmers tend to relax and slow down.
The upbeat phase is where most swimmers stand to gain a lot of ground on the competition and their own personal bests.
In a study with elite swimmers, researchers (Atkinson et al, 2014) found that the upkick phase is not just supportive but essential for fast dolphin kicking speed.
The fastest dolphin kickers were the ones that had a “symmetrical” kick velocity.
In other words, the swimmers kicked with the same toe velocity in both phases of the kicking motion.
To improve the upbeat or upkick phase, add vertical kicking, fish kicks, and be more mindful of this phase of the underwater dolphin kick.
Gretchen Walsh, Olympian and NCAA champion, credited a focus on this phase of her underwater dolphin kick during her 2023 collegiate season, where she dominated NCAAs with six golds and a silver medal.
“This year, we have been working on the upkick and utilizing both directions of the kick,” she said.
5. Vertical kicking
Vertical kicking is a kick drill that isolates the lower body and forces swimmers to kick in an upright position. The goal is to stay vertical and keep your head above water.
By introducing vertical kicking to your underwater dolphin kick training, you can improve body awareness of the movement, easily add resistance, and improve kicking speed and power.
A study (Mandzak et al, 2020) found that introducing a vertical kick set to the regular training of junior competitive swimmers significantly increased kicking velocity and improved distance per kick in 50m kicking time trials.
Vertical kicking is an excellent tool for balancing both phases of the kick, particularly helping swimmers master the upbeat phase (which we will cover next).
Vertical kicking can be done anywhere the pool is deep enough, is highly variable to a swimmer’s abilities (e.g. add resistance by raising arms out of the water), and completely isolates the kicking motion, making it easier to focus on proper kick technique and form.
6. Use swim fins
Swim fins are one of the best types of swim gear for competitive swimmers, and are crucial for improving the underwater dolphin kick.
Fins add surface area to the feet and toes, creating more resistance in the water and allowing swimmers the ability to really feel each phase of the dolphin kick. By kicking faster than without fins, swimmers learn optimal body position and amplitude for peak speed.
Swim fins are also a tool for increasing ankle flexibility, as the added surface area creates a gentle stretch when kicking.
Add underwater dolphin kick sets with fins to your regular training routine, in short bursts with plenty of rest to maximize power and strength development.
The optimal swim training fins for cranking up dolphin kick velocity are made of softer silicone that doesn’t crack and rip, flexes sufficiently to mimic the whip of the foot and ankle, and of course, is comfortable for powerful use!
7. Add Monofin training
Specialized fins like the Monofin are another tool swimmers can use to improve the underwater dolphin kick. Monofins, as the name suggests, are single blade fins that locks the feet together and creates added resistance for swimmers.
Benefits of Monofins include being able to master the “fish kick” (kicking on your side), increased speeds, and building more strength and power in the water.
The use of a monofin also gets us in the same neighborhood in terms of kicking efficiency as aquatic animals (Nicolas et al., 2007), serving as a bridge between what can often be clunky human locomotion and fish-like underwater movement.
Wrapping Things Up
Building and honing a faster underwater dolphin kick can often feel frustrating; like we are trying to learn how to salsa dance on roller skates.
By following some of the tips above, including working better undulation, emphasizing a thunderous upkick, increasing flexibility, and smartly using the right swim equipment, you can level up that dolphin kick and see faster breakouts and improved results.
Happy swimming!
ABOUT OLIVIER POIRIER-LEROY
Olivier Poirier-Leroy is a former national-level swimmer, author, swim coach, and certified personal trainer. He’s the author of YourSwimBook, a ten-month logbook for competitive swimmers.
He’s also the author of the best-selling mental training workbook for competitive swimmers, Conquer the Pool: The Swimmer’s Ultimate Guide to a High-Performance Mindset.
It combines sport psychology research, worksheets, anecdotes, and examples of Olympians past and present to give swimmers everything they need to conquer the mental side of the sport.
Ready to take your mindset to the next level in the pool?
👉👉 Click here to learn more about Conquer the Pool.
