Underwater Kick: The Complete Guide

What Is Underwater Dolphin Kick?

Underwater dolphin kick (AKA underwater kick, streamline dolphin kick, submerged dolphin kick, the fifth stroke, or simply underwaters) has grown dramatically in importance over the past several decades and is one of the most critical skills that separate the elite swimmers from everyone else.

The most effective underwater kick is when swimmers leave the wall underwater in a streamlined position and do dolphin kicks. The undulation creates a whip-like kick action that results in a lot of speed.

The advantage of underwater kick is that it creates much less drag compared to surface swimming. This allows you to generate more speed, even if there isn’t quite as much propulsion.

Historically, only butterflyers used the dolphin kick. In the 1970s, an American swimmer from Puerto Rico named Jesse Vassallo started taking two or three dolphin kicks off the wall to help avoid the waves created by other swimmers. A Japanese swimmer named Daichi Suzuki then began to experiment with extended underwater kick. By 1988, multiple swimmers were using underwater kick for distances of up to 35 meters. Currently, you’re only allowed to kick for 15 meters under the surface of the water each length during butterfly, backstroke, and freestyle races and on those legs during an individual medley.

Because they tend to be faster than swimming backstroke and butterfly for most swimmers, underwater kick is more prominent in these events than in freestyle races. You’re only allowed to do one dolphin kick as part of a breaststroke pullout during a breaststroke race.

Underwaters play a larger role in going fast in short course races compared to long course races. You can swim the first 15 meters of each length underwater, so it’s possible to spend a larger percentage of the race underwater during a short course race.

If you struggle to achieve the core power and coordination required for underwater kick, or if you have injuries or limitations that prevent you from creating the whip-like action, pushing off the wall and starting to swim right away after a short glide is perfectly acceptable, as is doing only one or two dolphin kicks. In freestyle and backstroke races, you have the option to do your underwaters with flutter kick instead of dolphin kick.

The Key Elements of Underwater Dolphin Kick

There are four main elements of an effective underwater dolphin kick. You must be able to:

1. Create stability to start your undulation. A great underwater kick starts with stability and control of your upper body. This is important for two reasons. First, you need stability to create the undulation that produces a fast and powerful kick. If you can’t begin the undulation, moving your body in a coordinated movement is very difficult. Second, the stability allows you to keep resistance as low as possible. If your body is moving all over the place, you’re creating a lot of resistance or drag.
2. Create propulsion with your down-kick. Your down-kick creates most of the propulsion of your kick when you’re on your stomach or side for butterfly or freestyle races. Your up-kick produces most of the propulsion during your underwater kicking in backstroke races.
3. Recover your legs during your up-kick. Although you can create some propulsion from your up-kick, the primary purpose of your up-kick during butterfly or freestyle races is to help set you up for another down-kick. Your down-kick serves this role during your underwater kick in backstroke races.
4. Maintain great alignment to create as little drag as possible. The more propulsion you can create, the faster you’ll be able to kick under the surface. The less drag, the faster you’ll be able to kick under the surface. Both are important.

While doing underwater kick, holding a great streamlined position is critical. Your arms should be locked and your hands stacked and clasped out front, your biceps squeezing your ears, and your spine relatively straight. Making yourself as small as possible reduces the amount of resistance as you move through the water.

Another key aspect of keeping resistance low is to control the amplitude in your underwater kick. Don’t do a large kick that goes outside your bodyline, which is cutting through the water in a tight streamline. This will create more drag. Keep your kick within your bodyline to maximize power and minimize drag.

Impact of Underwater Dolphin Kick on Your Body

Underwater dolphin kick is a full-body movement that uses many of the muscles of your body.

Your quadriceps, gluteals, and hamstrings are involved in the kick itself. Your abdominal muscles and back extensor muscles help create and control the undulation that contributes to the powerful and effective kicking action that gives you speed underwater.

Although how many calories you burn while doing underwater kick hasn’t been studied, you can assume that you burn calories at a similar rate as you would while swimming at the surface, provided the intensities are similar. Since the underwater kick can only be done for short periods of time, if your goal is to burn a lot of calories, include it in combination with swimming.

Underwater kick can cause or aggravate two common injuries.

The first is a back injury caused by the large volume of high-speed movements happening in your spine. The undulation of your kick requires repeated forward and backward bending of your spine. Although this movement isn’t inherently dangerous, if you do a lot of it, or you dramatically increase the volume of it, it can lead to overuse injury.

The second potential point of concern is your ankles. Like your back, your ankles will bend back and forth at high speeds. Unusually large volumes of underwater kick can be problematic for your ankles.

If you have mobility issues or previous injuries, be sure to approach underwaters with caution and start small, gradually building your skills. You can also substitute underwater flutter kick in freestyle and backstroke races. Although this isn’t as fast as dolphin kick, it can lead to faster swims than if you use no kick at all.

Common Reasons for Disqualification When Doing Underwater Dolphin Kick

The most common reason for disqualification during underwater dolphin kick is staying underwater beyond 15 meters during butterfly, backstroke, or freestyle races, or on those legs during an individual medley. Your head must break the surface of the water before the 15-meter mark.

Because of the added distance you go over the water during your start and the potential to dive too deep, 15-meter violations are more common after starts than after turns. Do your start cleanly and you’ll have fewer underwater kicks compared to when you’re doing a turn.

If you like to extend your underwater kicks, be aware of your kick count to ensure you don’t get disqualified. And if you wear technical suits, know how your suit changes your kick count. These are things to work on in workouts.

Some swimmers find that they can kick faster on their side, and although this is permissible, taking it too far can result in disqualification. Backstrokers can be on their side, but they must be angled toward their back. Butterflyers can be on their side, but they must be angled toward their front. Freestylers can push off at whatever angle they want. Swimmers must be on their front during the freestyle leg of an individual medley, however.

Some butterflyers get disqualified because their feet come apart when trying to do dolphin kick, which turns that kick into a flutter kick. Your legs must remain in sync throughout your underwater dolphin kick.

Letting your legs separate during underwater kick in backstroke and freestyle isn’t recommended, but it’s not against the rules. Make sure your legs are always moving at the same time in butterfly to avoid being disqualified.

How to Build Speed and Endurance for Underwater Dolphin Kick

Underwater dolphin kick is only a viable strategy if you can move underwater faster than you can on the surface. If you can’t, you’re better off swimming on the surface.

Building both speed and endurance in your underwater kick is critical. Sustainable speed comes from performing great skills, so creating a foundation of skill should be your first priority. Once that’s in place, change the emphasis to build more speed or endurance.

Even if you’re a great underwater kicker, you likely should only take a maximum of eight kicks. Underwater kick isn’t a skill that you need to be able to do for a long time. But you do need to do it fast. To build speed, a lot of your underwater kick work should be done over short distances or for short times. The quality of your kick in terms of skill and intensity is what matters most. Ensure that your effort is high and duration is short, and that you’re getting plenty of rest so you can go fast.

Building underwater kick endurance is all about being able to repeat faster underwater kicks during each length of your race, not about being able to kick for longer distances. There are two main approaches to doing this.

1. The first is to do a lot of short, fast kicks with shorter rest periods. This helps you learn to kick fast over and over again.
2. The second is to do a certain number of underwater kicks each length of your workout. This helps you learn to repeatedly and sustainably do your underwater kicks.

How to Include Underwater Dolphin Kick Work in Workouts

To help you improve your underwater dolphin kick skills during workouts, include a lot of drills and a lot of underwater kicking.

Most of your underwater kick work should be done with a fairly high level of intensity and effort. Underwater kick is always short and fast, and the implementation of underwater kick work into your workouts should reflect that.

A simple and effective way to include underwater kick work into your workouts is to take a predetermined number of underwater kicks off every wall during every set. You can do more during sprint sets and fewer during endurance sets. This helps you get a lot of practice in specific situations. If you want to be able to consistently and reliably do good underwater kicks in your races, you have to consistently and reliably practice them throughout your workouts. Developing this skill doesn’t happen by chance.

Underwater kick drills and doing a set number of underwater kicks off every wall during your workouts are complementary approaches to improving your underwater kick. You need both. Doing a lot of underwater kick drills and sprints at high speed is great for learning and perfecting new skills. The drawback is that you’re not performing these skills while you’re swimming as you would in a race. Adding underwater kick to your swim sets won’t always help you learn new skills, but it’ll help you learn how to perform those skills while you swim, which is critical for getting your skills to show up in races.

Individual Differences and Modifications to Underwater Dolphin Kick

Elite swimmers don’t use the same underwater dolphin kick strategies, and the same thing happens at other levels of competition. This is for two reasons:

1. The first reason is that swimmers come in different shapes and sizes. Some are taller, shorter, stronger, weaker, more mobile, less mobile, use their upper bodies more, etc. This means different kick rates and different ranges of motion. Each swimmer will be a little different. It’s all about figuring out what’s fastest for you.
2. The second reason is that different events tend to encourage (or discourage) different underwater kick strategies. Because you won’t breathe when doing underwaters, you tend to see shorter underwaters during longer races, when swimmers need air more often. Some swimmers hold their underwaters longer during long course races than during short course races because they don’t have to hold their breath as often. Stroke matters as well. Most swimmers are faster underwater than they are on the surface swimming backstroke or butterfly, so in these events many swimmers extend their underwaters. Some swimmers are faster underwater than they are while swimming freestyle, but this is less common. As a result, most freestylers tend to shorten their underwaters and begin swimming on the surface sooner.