You can have a strong freestyle pull and still feel as if the water is holding you back when your legs sink or your kick burns out too early. What are flutter kicks in swimming? They are the small, alternating leg movements used mainly in freestyle and backstroke to support body position, rhythm, and forward motion. I’ll break down how the kick works, how to practice it, which mistakes slow swimmers down, and when equipment such as fins or a kickboard actually helps.
The flutter kick is small, steady, and driven from the hips
- Definition: Each leg moves up and down in an alternating rhythm.
- Main strokes: It is used most often in freestyle and backstroke.
- Correct movement: Initiate the kick from the hips, keep the knees soft, and point the ankles.
- Biggest mistake: Bicycle-style kicking from the knees creates drag and wastes energy.
- Best practice: Short kick sets of 25 yards or meters make it easier to maintain good form.
What the swimming flutter kick actually does
A flutter kick is a continuous sequence of alternating kicks. While one leg moves slightly downward, the other returns upward, creating a narrow, quick rhythm rather than a large leg swing. The movement should come mainly from the hips and upper legs, with the knees bending naturally instead of driving the action.
In freestyle, the kick helps keep the legs near the surface, supports a streamlined body line, and contributes some propulsion. Its bigger role is often balance. U.S. Masters Swimming describes the kick as something that helps hold the stroke together, which matches what I see in practice: a technically modest kick can make the entire swim feel smoother.
Backstroke uses the same alternating pattern while the swimmer lies on the back. The position changes how the kick feels, because the legs must help maintain buoyancy and prevent the hips from dropping. In both strokes, the goal is not to splash as much as possible. The goal is consistent movement with minimal drag.
How to perform a flutter kick correctly
Start with a long body line
Stretch your body from the crown of your head through your hips and legs. In freestyle, keep your face in the water with your eyes looking down, while in backstroke keep your head relaxed and your ears close to the surface. A dropped head or lifted chin can change the angle of the whole body and make the legs sink.
Kick from the hips
Imagine your legs are long fins attached to your hips. The upper leg begins the motion, the knee follows with a small bend, and the ankle finishes the kick. Keep the legs relatively close together and let the feet move just below the surface, producing little splash rather than forceful waves.
Keep the ankles loose
Point your toes gently and relax your ankles. A stiff ankle acts like a paddle facing the wrong direction, while a relaxed ankle lets the top of the foot press against the water during the downward motion. Do not force an exaggerated ballet point, though. Tension in the feet can travel up into the calves and create cramping.
Find a sustainable rhythm
There is no single kick speed that suits every swimmer. A six-beat kick uses three kicks per arm cycle and is common when swimmers need speed, while a two-beat kick uses fewer kicks and can conserve energy during longer distances. I usually tell developing swimmers to find the smallest kick that keeps the hips high before trying to kick faster.
How flutter kicks fit into freestyle and backstroke
The kick does not work in isolation. In freestyle, your legs should support the body rotation created by the shoulders and hips. When you breathe, the kick helps prevent the lower body from swinging or dropping, but it cannot fully compensate for lifting the head or over-rotating.
In backstroke, the feet should travel close to the surface while the hips remain high. The downbeat may feel stronger than the upbeat, but both directions should remain controlled. A useful check is whether your knees stay mostly underwater. If they break the surface repeatedly, you are probably bending too much from the knees.
| Stroke | Body position | Main purpose of the kick |
|---|---|---|
| Freestyle | Face down | Supports balance, body rotation, and forward speed |
| Backstroke | Face up | Maintains buoyancy, body line, and rhythm |
| Butterfly | Face down | Uses a simultaneous dolphin kick instead |
| Breaststroke | Face down | Uses a frog-style whip kick instead |
This distinction matters because swimmers sometimes try to use a flutter kick in every stroke. It belongs naturally to freestyle and backstroke, while butterfly and breaststroke depend on completely different leg mechanics.
Common mistakes that make the kick ineffective
Kicking from the knees
The classic error looks like pedaling a bicycle underwater. Large knee bends increase frontal resistance and make the feet travel too far up and down. Think about shortening the range of motion and letting the hips start each kick.
Making the kick too large
A powerful-looking kick is not automatically an effective one. If your feet move a foot or more vertically, you are likely spending energy pushing water downward instead of moving your body forward. For most freestyle swimming, a compact kick is easier to sustain and creates less drag.
Locking the ankles
Rigid feet reduce the surface area that can push against the water. This often causes calf fatigue, foot cramps, and a feeling that the kick produces no speed. Relax the ankle and allow the foot to respond to the water instead of forcing every movement.
Holding the breath during kick drills
Kick sets can feel deceptively hard because the face often remains in the water for longer. Exhale continuously underwater and turn or lift the head only when needed. Poor breathing can make a technically good kick collapse within a few lengths.
Using a kickboard as a permanent solution
A kickboard isolates the legs, which makes it useful for learning rhythm and building endurance. It also changes your body position by lifting the chest and sometimes dropping the hips. I use it as a diagnostic tool, not as proof that the kick will transfer perfectly to full-stroke swimming.
Simple drills to improve your flutter kick
Streamline kick on the back
Push off the wall with both arms extended overhead and your hands stacked. Keep the ribs controlled, the hips near the surface, and the kick narrow. This drill quickly exposes whether your knees are doing too much work because there is no kickboard to hide a sinking body line.
Side kick drill
Lie on one side with the lower arm extended and the upper arm resting along your thigh. Kick gently for 25 yards or meters, then switch sides. Side kicking teaches you to keep the legs active while maintaining balance and prepares the body for freestyle breathing.
Kick with fins
Short fins can make the correct ankle position easier to feel and provide enough propulsion to keep the body high. Use them for technique, such as 4 x 25 with relaxed effort, rather than kicking maximally until your form disappears. Fins are helpful feedback, but they can also hide weak ankles when used for every set.
Read Also: Backstroke Alignment - Fix Your Form, Swim Faster
A practical beginner set
Try this short session after an easy warm-up:
- 4 x 25 easy flutter kick on the back with 20 seconds of rest
- 4 x 25 side kick, switching sides halfway through each length
- 4 x 50 freestyle, focusing on a quiet and steady kick
Rest enough to preserve technique. If your knees begin to lead the movement or your lower back starts arching, stop the drill, reset your position, and continue at an easier pace.
How hard should flutter kicks feel
Flutter kicking uses the hip flexors, quadriceps, calves, glutes, and trunk muscles, but the sensation should not be an all-out burn from the first length. During technique work, aim for a level where you can maintain a relaxed face, steady breathing, and a compact kick for the entire distance.
For conditioning, you can increase the distance, reduce rest, or add fins, but change only one variable at a time. A reasonable progression is to move from 8 x 25 to 6 x 50 while keeping the same controlled rhythm. More kicking is not automatically better if every repetition reinforces poor mechanics.
Stop if you feel sharp pain in the lower back, hip, knee, or ankle. Muscle fatigue and mild calf tension are common, but persistent pain usually points to a position or mobility problem that deserves attention from a qualified coach or health professional.
Make every kick support the stroke
The most useful flutter kick is rarely the most dramatic one. Keep your body long, start the movement at the hips, relax the ankles, and choose a rhythm you can maintain without disturbing your breathing or arm recovery.
When I review a swimmer’s kick, I look first at the body line and ankle flexibility, not at how hard the feet are moving. A quiet kick that keeps the hips high and the stroke connected will usually take you farther than a frantic kick that creates plenty of splash but little forward progress.
