Butterfly Kick: The Complete Guide

Introduction to the Butterfly Kick

Although your pull provides much of your propulsion in butterfly, your kick plays a critical role in sustaining speed. Your kick accomplishes two things:

• It propels your body down the pool. Although this propulsion isn’t as much as your pull creates, it makes a big difference.
• It moves your hips up. There are two key points in your stroke that are critical for helping you go fast: when your hands enter the water and when they exit the water. Kicking when your hands enter the water allows you to get your hips up and reestablish great alignment. Kicking when your hands exit the water allows your arms to be in an effective position to recover smoothly.  

These two kicks differ slightly in how they’re done. When your hands are exiting the water, your kick is done with your body at an incline, especially if you’re breathing. When your hands are entering the water, your kick is done with your body horizontal. Both kicks need to be perfected to create as much speed as possible. 

The major muscles of your legs and hips help power your kick. Your hip flexors and quadriceps are responsible for creating the forces that produce a great down-kick. The muscles on the backs of your legs, your hamstrings and glutes, create the forces necessary for a great up-kick. 

To do a great kick, your hips need to be relatively stable and controlled. The muscles of your torso ensure that your legs have a great base to kick from. Your abdominal muscles on the front of your body and your erector spinae muscles on the back of your body help control your hips so you can kick effectively. 

How Your Butterfly Kick Powers You Down the Pool 

Your butterfly kick creates speed because it adds propulsion to each stroke cycle. Your kick pushes backward against the water, which moves you forward. The more you push backward against the water, the more you can move forward with each kick. Developing a stronger kick allows you to create and maintain more speed during the more difficult parts of the stroke when you’re not generating propulsion with your arms. 

When your hands exit the water, you aren’t creating any propulsion with your arms or legs. To make matters worse, your body is elevated, which creates a lot of resistance. These two factors will lead to a loss of speed. Doing a powerful kick at the end of your pull as your arms are exiting allows you to create as much propulsion as possible. The more speed you have going into your recovery, the faster your arms will be moving throughout your whole recovery.  

After your arm recovery, kick again as your hands enter the water. As with the previous kick, this kick is beneficial for improving your hip position in the water. For now, remain focused on the positive impact this kick has on your propulsion. By kicking right after your recovery, you’re able to create more propulsion with your legs to maintain or improve speed while preparing for your pull. This kick reduces the time between propulsive actions, allowing you to maintain forward speed. 

The Importance of Lifting Your Hips During Your Butterfly Kick

In addition to creating propulsion, your kick also lifts your hips, which helps you maintain a proper body position and, therefore, go faster.  

Every butterfly kick is directed down and back. Kicking back moves your hips forward, and kicking down moves your hips up. By kicking at the right time in your stroke cycle, you can move your hips up in the water to help create more speed. 

During your pull, you’ll begin to lift your upper body in the water to help you accelerate through your pull and prepare for your arm recovery. By lifting your upper body, your hips will begin to sink lower. When you breathe, this effect will be more significant. This creates a problem because the lower your hips are, the lower your arms will be at the end of your pull. This will make it more difficult to recover your arms. 

By kicking strongly at the finish of your pull, however, your hips will be lifted. This allows your hands to be right at the surface at the conclusion of your pull, which means faster and easier arm recoveries. 

When your hands enter the water, your body has been at an incline during your arm recovery, which increases the amount of resistance you face. The longer you spend in this position, the more resistance you’ll create and the more speed you’ll lose. When you kick on hand entry, you’ll lift your hips and reestablish a horizontal position in the water. This reduces resistance by improving speed, all facilitated by an effective kick. 

Differences Between the Two Kicks in Butterfly 

Although both kicks have a similar influence on your hips, they’re used for very different reasons at very different points in your stroke cycle. More important, they occur when your body is in very different positions. 

When your legs kick as your hands exit the water, your body is at a steep incline because of the elevation of your shoulders prior to recovering your arms. When your legs kick as your hands enter the water, your body is level in the water.  

Although this may not seem like a significant issue, your change in body position represents two different kicking skills. Kicking with your body at an incline is different than kicking with your body horizontal in the water. Although the general motions are similar, the angle of your body influences the angle of your legs and how your feet interact with the water during each kick. 

It’s not uncommon to see some swimmers who are much faster when kicking with a kickboard than when kicking with their head down and with a snorkel. Likewise, you’ll see some swimmers who are much better kickers without a kickboard and with their head down than they are with a kickboard. This indicates there’s a difference in the skills, and for these swimmers, differences in the relative strengths of their kicking skills.  

If your goal is to perfect your butterfly, you’ll want to be skilled at doing both kicks. This often requires kicking in different positions during your workouts to ensure that you’re developing and perfecting all the necessary skills. 

The Down-Kick 

As the name down-kick implies, you’re kicking downward in the water. For the up-kick you’re kicking upward in the water. Although each plays distinct roles and requires distinct skills, both kicks are critical for a fast butterfly kick.  

The down-kick is the motion that provides most of the propulsion during your butterfly kick. It’s the kick that moves your hips forward and up in the water. The kick has a whiplike kicking action that travels like a wave—or undulation—down your body. As the wave travels down your legs, it gets bigger and faster, and finishes with a fast snap of your feet, in which the tops of your feet, your insteps, press backward against the water and create speed. 

A common mistake many swimmers make is trying to kick from only their hips or trying to kick from only their knees. In both cases, you’ll be compromising your kick. An effective down-kick involves your core, hips, knees, and ankles to push against the water as much as they can. 

Your kick starts from your hips with your thighs beginning to move down in the water. Once your thighs get moving, motion will start at your knees and your shins will begin moving down in the water with more and more speed. Finally, motion will start at your ankles, and your feet will begin moving with more and more speed. 

This whole motion occurs very fast, and as more and more joints are involved, the wave becomes bigger and faster until it reaches your feet. Your feet will move quite fast through a large range of motion. This motion is what ultimately creates the propulsion necessary to move your hips up and forward in the water. 

The Up-Kick 

Although your down-kick gets much of the attention and creates most of your propulsion, that doesn’t mean your up-kick is any less important. Your up-kick facilitates an effective down-kick, and without a great up-kick, your down-kick won’t be nearly as beneficial and won’t happen nearly as often. 

An effective up-kick must be done correctly and fast. In contrast to your down-kick, your up-kick is done with a mostly straight leg. Although motion occurs from your hips, knees, and ankles during your down-kick, in your up-kick most of the motion occurs from your hips. Your knees shouldn’t bend, and not much should happen with your ankles. Your legs come straight up in the water.  

The reason this is so important is because your whole leg needs to be level in the water to do the whiplike down-kick. Snapping down in a whiplike manner creates the speed and range of motion necessary for a great kick. 

If you bend your knees to do your up-kick, your feet might be in the right position in the water, but the rest of your legs won’t be. Your only option then would be to bring your feet down by kicking from your knees. This limits the contribution from your hips, which limits the range of motion and speed of your kick. That adds up to less effective kicking and slower swimming. 

Although the skilled execution of your up-kick is key, the speed at which it’s done matters as well. The faster it occurs, the sooner your next down-kick can occur. If your up-kick is slow, one of two things will happen. Either you’ll disrupt your kick timing, or you’ll simply slow down your arms to maintain your timing. In both cases, you slow down. 

Common Kicking Mistakes 

There are several common butterfly kick mistakes that slow you down: kicking at the wrong time, failing to do the down-kick correctly, or failing to do the up-kick correctly.  

• You should do two butterfly kicks per stroke cycle, and these should occur at specific times for specific reasons. The purpose of your kick is to lift your hips in the water and propel you down the pool. Your kicks should occur when your hands exit the water and when they enter the water, because that’s when you need your hips to come up in your stroke and when you need to generate propulsion. Kicking at the wrong time will cost you speed.
• How you do your kicks matters as well. If you just bend your knee to raise and lower your feet in the water, that’s going to prevent you from doing a great down-kick, which is critical to generating as much speed as possible. By keeping your legs straight on your up-kick and whipping your legs down, you’ll create as much propulsion as possible.
• Your kicks also need to be done quickly. If your two kicks are slow, getting the timing right is tough. Or you may keep your timing but slow down your arms, which slows you down.
• Failing to keep your legs together slows you down as well. More important, if they aren’t moving simultaneously, you’ll be disqualified in a meet. 

Butterfrog 

Butterfly evolved out of breaststroke, which was originally done as it is now: with a breaststroke kick and breaststroke pull. Some swimmers in the mid-20th century began to recover their arms over the water while still doing breaststroke kick. Eventually, they began doing dolphin kick with an overwater recovery, leading to the creation of butterfly as we know it today. 

USMS rules dictate that butterfly and breaststroke are distinct strokes. Butterfly requires an overwater recovery; you can do breaststroke with your elbows underwater, but you can bring your hands forward under, at, or over the surface of the water. Breaststrokers must do a frog kick, but USMS rules allow butterflyers to do either a dolphin kick or a frog kick, which is often called butterfrog. In other words, you can swim butterfly with an overwater recovery and a breaststroke (or frog) kick.  

This alternative to butterfly can be advantageous to some swimmers. If you find breaststroke kick to be more comfortable and you prefer to keep your feet turned out, butterfrog may be a great alternative for you. Likewise, if you have a strong breaststroke kick but are struggling with learning butterfly, butterfrog can serve as a great intermediary in which you can get comfortable with overwater arm recovery. 

Butterfrog also presents an interesting option if you find that you quickly fatigue while swimming butterfly. Although butterfly doesn’t allow for any breaks in your stroke cycle without disrupting your timing, butterfrog can allow you to be more patient with your arm pulls. This can help you finish sets, workouts, and races that would otherwise be very difficult to complete.