Muscles worked
What the flutter kick trains
Tap a muscle to see just that one and what it does in the lift.
Before the first rep
How to set up
- 01
Lie flat. Lie on your back on a mat with your legs straight and your head resting on the floor. Keep your neck relaxed.
- 02
Place your hands. Put your arms by your sides with palms down, or slide your hands under your hips if you need a little help keeping your lower back down.
- 03
Flatten your lower back. Breathe out, pull your ribs down and press your lower back into the mat. You should not be able to slide a hand under it.
- 04
Lift your legs. Keeping your back flat, lift both straight legs off the floor. Start fairly high, around 45 degrees, and over the weeks work down toward a few inches off the floor, only as low as your lower back stays down.
Step by step
How to do the flutter kick
- 01
Start the kicks. Raise one leg a few inches while the other lowers a few inches, then switch. Legs stay long with toes pointed.
- 02
Keep them small and quick. Each kick is short, only a few inches. Think of a steady, quick rhythm rather than big swings.
- 03
Keep your lower back down. This is the whole exercise. Your lower back stays pressed into the mat on every kick. If you feel it start to lift, raise your legs higher until it is flat again.
- 04
Keep breathing. Take short breaths in and out while you kick, keeping your belly tight. Do not hold your breath for the whole set.
- 05
Finish. At the end of the set, bend your knees, put your feet on the floor and then relax. Count kicks per leg or work for a set time.
Cues to say in your head
- Lower back stays down
- Ribs down, belly tight
- Small, quick kicks
- Long legs, pointed toes
- Back lifts? Legs higher
- Keep breathing
Fix these first
Common mistakes
Lower back arching off the floor
Raise your legs higher, slide your hands under your hips, or bend your knees slightly. Only lower your legs as far as your back stays flat.
Big, slow swings
Keep each kick to a few inches. Large swings turn the move into momentum and make it harder to keep your back down.
Dropping the legs too low too soon
Lower legs are harder, not better. Start near 45 degrees and work down toward a few inches off the floor over weeks, as long as your lower back stays flat.
Holding your breath
Breathe in short, steady breaths through the whole set while keeping your belly braced.
Straining your neck
Rest your head on the mat and keep your jaw and neck relaxed. The work belongs in your abs.
Stay safe
Flutter kicks are low risk when your lower back stays on the floor. If you feel your back arch or start to ache, stop the set, bend your knees and set your feet down, then try again with your legs higher or your hands under your hips. Stop if you feel sharp pain in your back or hips, and get advice from a doctor or physical therapist if back pain keeps coming back with core work.
Programming
Sets, reps and how much weight
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Technique | 2 to 3 | 10 to 15 kicks per leg | 40–50% 1RM | 30 to 60 sec |
| Endurance | 3 | 20 to 40 sec | 50–65% 1RM | 30 to 60 sec |
Plan your next session
Put in a recent set. You get working weights for your goal, a warm-up and the plates to load.
Estimated 1RM 216 lb
Endurance sets
108–140lb
3 sets of 20 to 40 sec reps, 30 to 60 sec rest. Build time before you lower your legs. End the set when your back starts to lift.
Estimates use the Epley formula and work best from sets of 3 to 8 reps. Treat them as a starting point and adjust by how the first working set moves.
Questions
Flutter Kick questions
What muscles do flutter kicks work?
Mainly the abs (rectus abdominis) and the deeper transverse abdominis, which hold your lower back flat. Your hip flexors move your legs, and your obliques help keep your trunk steady.
Do flutter kicks work your abs?
Yes, as long as your lower back stays pressed to the floor. That is your abs working to hold your pelvis still. If your back arches, your abs are no longer holding that position and more of the strain tends to land on your lower back.
Why do flutter kicks hurt my lower back?
Usually because your legs are too low for your current strength and your lower back lifts off the floor. Raise your legs higher, put your hands under your hips, or bend your knees slightly, and stop if it still hurts.
How long should you do flutter kicks?
Start with 2 to 3 sets of 10 to 15 kicks per leg, or 20 to 30 seconds, and build toward 40 seconds. Stop each set when you can no longer keep your lower back down.
Should I put my hands under my hips?
It is fine, especially when you are starting out, because many people find it easier to keep their lower back flat that way. As you get stronger, move your arms to your sides.
Train in Protocol
Log your flutter kick by voice. Protocol tracks the rest.
Your last session shows up before every set, warm-ups and plates are worked out for you, and your coach sees every lift next to your sleep and recovery.