Flutter Kicks
Also works: Hamstrings
Not the ab drill of the same name. This version has you face down with your hips at the edge of a bench and your legs hanging free, alternating small leg lifts against gravity. It is a low-load hip extension drill for the glutes and hamstrings, useful for accumulating contraction time rather than building strength.
Own the movement
Set up first, then execute. Every cue below is something you can check on your next set.
Before the first rep
- Lie face down with your hip bones just past the end of the bench, so your legs can drop below hip level.
- Hold the front edge or sides of the bench with both hands and pull yourself gently towards your head to stop sliding.
- Squeeze your glutes to raise both straight legs until they are level with your hips. That is rep zero, not the floor.
- Tuck your chin slightly and keep your ribs down — the movement should not start in your lower back.
Every rep
Breathing & tempo — Breathe normally and continuously through the set; holding your breath across 30 alternations is pointless. Keep a metronomic pace of about one leg swap per second.
Sets, reps & load
Where to start, and what to change when it stops being hard.
Bodyweight only, and that is the ceiling here. Progress by extending the set from 20 seconds to 60 seconds of unbroken work, then by adding light ankle weights of 1-2 kg. Once ankle weights start needing to be heavy, you have outgrown the drill — move to loaded bridges or hip thrusts instead.
What goes wrong
The errors that show up most often, and the cue that fixes each one.
Set a floor for the movement: neither heel goes below the height of your hip crease. If you cannot hold that, cut the set short rather than sinking into the rest position.
Press your hip bones into the bench and keep your ribs pulled down. Range above hip level should be small — 15-20 cm is plenty, anything more is spinal extension, not hip extension.
Slow to about one swap per second and count time instead of reps. Aim for 30-45 seconds of continuous work per set.
Pair it with a loaded hip extension — hip thrusts, bridges or pull-throughs — and use flutter kicks as the warm-up or the finisher around them.
Why bother
With your hips at the edge of the bench and your torso pinned to it, the only joint that can move is the hip. That removes the lower-back-driven cheat that makes standing and quadruped kickbacks so easy to fake, and leaves the glutes and hamstrings holding your leg against a lever arm about a metre long.
Be honest about the load. Your leg is roughly 15% of your bodyweight, so even for a heavy lifter this is a light drill. The value is the alternating rhythm: one leg is always holding an isometric at hip level while the other moves, so total time under tension is far higher than the rep count suggests.
Where it fits
Treat it as warm-up or finisher work, never as the reason you trained legs. Two sets of 20-30 alternations before squats or hip thrusts wakes up the posterior chain; the same at the end of a session adds cheap volume. It cannot replace a loaded hinge or bridge.
If this one isn't it
No kit, too hard, or too easy — here's where to go instead.
Same job, different kit
Start here instead
When this gets easy
Asked and answered
Isn't this an ab exercise?
There are two exercises with this name. The one most people mean is done lying on your back, scissoring the legs above the floor, and it trains the hip flexors and anterior core. This one is face down over a bench and trains hip extension — glutes and hamstrings. Same name, opposite muscles, so check which version a program means before you do it.
Can I do these without a bench?
You can lie face down on the floor, but the range collapses: the floor stops your legs at hip level, so you only get the top 15-20 cm and no stretch. If a bench is not available, a hip bridge or a band hip extension gives you far more usable range.
How is this different from a reverse hyperextension?
Same body position, different intent. A reverse hyper uses a dedicated machine, moves both legs together against a loaded pendulum, and is a genuine strength movement for the glutes and erectors. This is the unloaded, alternating, bench-only cousin — no swing, no plates, and a fraction of the stimulus. If your gym has a reverse hyper, use it and keep flutter kicks for warm-ups.
Should I feel this in my hamstrings?
Some hamstring involvement is normal and fine — they extend the hip too. But if the hamstrings cramp and the glutes never fire, your pelvis is probably tipped forward. Squeeze your glutes before the first rep and keep your ribs down so the glute starts the movement.