Plank Form

Check your plank with your phone

RepSensei has a detailed plank check. Prop up your phone and it counts your hold and flags these issues as you move:

• Hips sagged
• Hips too high

Put your phone on the floor, side-on, about 2 metres away. Keep your head to toes in view. The plank check is newer and has had less testing on real movement, so expect more misses. It sees one angle, so it won't catch everything.

How to do it

1. Kneel on the floor and place your forearms down with elbows under your shoulders.
2. Step your feet back one at a time so your body forms a straight line from head to heels.
3. Squeeze your glutes, brace your stomach and tuck your ribs down slightly towards your hips.
4. Push the floor away with your forearms so your upper back is not sagging between your shoulder blades.
5. Breathe steadily and hold for as long as you can keep this exact position, then lower your knees.

Coaching cues

Squeeze the glutes

Tight glutes stop the lower back from sagging and switch on the trunk muscles.

Ribs to hips

Pulling them gently together flattens the lower back.

Quality over time

Stop the set when the position breaks, not when the timer ends.

Common mistakes and how to fix them

Hips sagging

The lower back takes the load instead of the abs, which can feel uncomfortable. Fix: Squeeze your glutes and tuck the pelvis slightly. End the set when you can no longer hold it.

Bum piked up

Raising the hips takes the load off the abs. Fix: Lower the hips until shoulders, hips and ankles line up.

Holding your breath

It makes long holds feel harder and can spike your heart rate. Fix: Breathe slowly through the nose while staying braced.

Chasing long times

Several minutes of loose planking does little and gets boring. Fix: Do several 20 to 45 second holds with full tension, or move to harder versions.

Head dropping or craning up

It throws the neck out of line. Fix: Look at the floor just in front of your hands.

Muscles worked

Main: Abs. Also: Obliques, Shoulders, Glutes, Quads.

Who should take care

If your lower back aches during planks, check that your hips are not sagging, or start from your knees. Pain that persists is a reason to see a doctor or physiotherapist.

Variations

• Push Up to Side Plank: Harder: add a rotation into a side plank.
• Dead Bug: Easier: core control lying on your back.
• Barbell Ab Rollout - On Knees: Harder: a rolling plank from the knees.
• Pallof Press: Alternative: a standing anti-rotation core exercise.

Filming your plank

Place the phone on the floor side-on, about two metres away, so your whole body from head to feet is in frame. RepSensei has a detailed camera check for the plank that times your hold and flags some visible issues from that one angle; it cannot see everything. See how to film your form.

Questions

How long should I hold a plank?

For most people, 20 to 60 seconds with full tension is plenty. Once you can hold a minute, make it harder rather than longer.

Should I plank on my elbows or hands?

Both are fine. Forearms are more common; hands add more shoulder work.

Do planks burn belly fat?

No exercise burns fat from one spot. Planks strengthen the trunk; overall fat loss comes from diet and total activity.

See the Plank exercise guide with a 3D figure.

General guidance, not medical advice. Stop if anything hurts. The camera can miss things, so no issue seen doesn't mean perfect form.