Flutter Kicks: Form, Benefits and Common Mistakes
Flutter kicks look simple, but most people do them with an arched back and fast, sloppy legs. Here's how to make them a genuinely useful core exercise.
Flutter kicks are a bodyweight core exercise where you lie on your back, hold your legs a few inches off the floor and kick them up and down in small, alternating movements. They mainly train your abs to hold your pelvis and lower back steady while your legs move, which makes them an anti-extension and endurance exercise more than a muscle builder. Done with a flat lower back and controlled kicks, they're a solid finisher. Done with an arched back and frantic legs, they mostly tire out your hip flexors.
What flutter kicks work
- Rectus abdominis: keeps your pelvis from tipping forward under the weight of your legs, with noticeable work in the lower region.
- Transverse abdominis: your deep core helps you stay braced throughout.
- Hip flexors: hold your legs up and drive the kicking. They do a lot here.
- Obliques: help stabilize as your legs alternate.
The key thing to understand is that your abs aren't really moving during flutter kicks. Their job is to resist movement, specifically the pull of your legs trying to arch your lower back. That's why your back position matters so much.
How to do flutter kicks
- Lie on your back on a mat with your legs straight. Place your hands by your sides, palms down, or under your glutes for a little support.
- Brace your core and press your lower back gently into the floor. Keep your ribs down.
- Lift both legs so your heels are roughly 15-30 cm (6-12 inches) off the floor. Higher is easier; lower is harder.
- Kick one leg up a few inches while the other moves down, then switch, in a steady rhythm. Keep the movement small and controlled.
- Keep breathing throughout. Short, steady breaths are fine; don't hold your breath.
- Continue for your target time or reps, then lower your legs with control.
Optional: lift your head and shoulders slightly off the floor in a small crunch position. This adds more upper ab work, but only do it if your neck stays relaxed.
Common mistakes
Arching your lower back
If you can slide a hand easily under your lower back, it's arching. This shifts the strain to your spine and hip flexors. Raise your legs higher or bend your knees slightly until you can keep your back flat.
Kicking too big
Big, sweeping kicks turn the exercise into a swinging motion. Keep each kick to a few inches.
Going too fast
Speed hides poor control. A steady, moderate tempo is more effective than frantic kicking.
Pointing your legs too low too soon
The lower your legs, the harder it is. Plenty of people start with their heels an inch off the floor because it looks hardcore, then arch through the whole set.
Tensing your neck and shoulders
If you lift your head, keep your chin slightly tucked and your gaze toward your thighs. If your neck aches, put your head down.
Easier and harder versions
| Version | Difficulty | How |
|---|---|---|
| Bent-knee flutter kicks | Easier | Knees bent about 45 degrees to shorten the lever |
| High flutter kicks | Easier | Legs at 45 degrees or higher |
| Standard flutter kicks | Moderate | Legs 15-30 cm off the floor |
| Flutter kicks with head lifted | Harder | Upper back off the floor in a hollow-style position |
| Slow tempo flutter kicks | Harder | 2 seconds per kick |
| Scissor kicks | Similar | Legs cross side to side instead of up and down |
| Hollow body flutter kicks | Hardest | Arms overhead in a full hollow position |
If the hollow position is new to you, our hollow body hold guide is a good place to build it first.
Are flutter kicks good for building abs?
They're useful, but with limits. Because they're low-load and long-duration, flutter kicks mainly build endurance and control in the anti-extension pattern. They're not the most efficient way to build ab muscle size. For that, you want exercises that take your abs through a range of motion under meaningful load, like reverse crunches, cable crunches and hanging leg raises.
A good way to think about flutter kicks:
- Great as a finisher at the end of an ab session
- Good for building the control you'll need for harder exercises like leg raises
- Useful in circuits and conditioning workouts
- Not a replacement for progressive, loaded ab training
How many flutter kicks should you do?
Time-based sets work best. A reasonable starting point:
| Level | Sets | Time | Rest |
|---|---|---|---|
| Beginner | 2-3 | 15-20 seconds | 45 seconds |
| Intermediate | 3 | 30 seconds | 30-45 seconds |
| Advanced | 3-4 | 40-45 seconds, or slow tempo | 30 seconds |
Once you can hold good form for 45 seconds, make it harder by lowering your legs, lifting your head into a hollow position or slowing the tempo, rather than going for two minutes. You can use the free interval timer to run work and rest periods without watching a clock.
Sample ab workout with flutter kicks
Rest 45 seconds between sets. About 15 minutes.
- Reverse crunch: 3 sets x 12 reps
- Crunch with a 2-second hold: 3 sets x 12 reps
- Side plank: 2 sets x 30 seconds per side
- Flutter kicks: 3 sets x 30 seconds
Putting flutter kicks last means your abs are already fatigued, so focus extra hard on keeping your back down. If you'd like a different mix, the ab workout generator builds sessions based on your level and equipment.
Flutter kicks vs leg raises
Both involve lying on your back and moving your legs, but they train slightly different things. Flutter kicks keep your legs near the floor and emphasize sustained anti-extension. The lying leg raise moves your legs through a big range, which loads your abs more heavily during the lowering phase. Leg raises are usually the better strength builder; flutter kicks are a good endurance and control complement.
Are flutter kicks bad for your back?
Not inherently. They become a problem when your lower back arches, which is very common. Keep your legs high enough to maintain a flat back, and stop the set when you can't. If you already have lower back pain, check with a doctor or physical therapist first, and see our article on core training and lower back pain for general guidance.
Flutter kicks won't burn belly fat
It's a common claim that flutter kicks "target belly fat." They don't. No ab exercise burns fat specifically from your stomach; fat loss comes from an overall calorie deficit maintained over time. Flutter kicks burn very few calories compared with walking, running or a full-body workout. Train them for core control, and handle fat loss through nutrition and overall activity. Our guide on how to lose belly fat covers the approach that works.
Where AbShred fits
AbShred is an upcoming iPhone app that estimates six ab zones, including Lower Abs and Deep Core, from one photo and builds a weekly plan starting with your weakest zone, with exercise demos. It's an AI estimate for fitness motivation, not a medical measurement. You can join the waitlist at abshred.com.
FAQ
What do flutter kicks work?
Mainly your rectus abdominis and deep core, which work to hold your lower back flat, plus your hip flexors, which move your legs. Your obliques help stabilize.
Why do flutter kicks hurt my lower back?
Usually because your back is arching off the floor. Raise your legs higher, bend your knees, or place your hands under your glutes. If pain continues, stop and get it checked by a professional.
How long should I do flutter kicks?
Sets of 20-45 seconds with good form work well. Longer sets aren't more effective if your form breaks down.
Are flutter kicks better than crunches?
They train different things. Crunches work spinal flexion and the upper abs more; flutter kicks train anti-extension and endurance. A balanced routine uses both kinds of movement.
Can flutter kicks give me a six-pack?
They can help strengthen your abs, but a visible six-pack mostly depends on body fat. Combine ab training with sensible nutrition and patience.