Plank form check: a live coach on your phone
The plank is a test of holding one straight line from your shoulders to your ankles for as long as you can keep it. What matters is not just the time but how much of it is in good form: a hold that is a minute long but sags for half of it is training your lower back more than your abs. Formanti times the hold and tells you when the line breaks.
No equipment needed. Practise at home. Just do the rep properly in front of your phone. Bodyweight squats, push-ups and lunges need nothing at all, and you can check the hinge and press patterns with a very light weight or none: the coach judges your movement, not your kit.
What good looks like
- Set your elbows or hands under your shoulders and your feet hip-width apart, with your body in one straight line.
- Squeeze your glutes and brace your abs as if bracing for a light punch, and keep your head in line with your spine.
- Keep your hips level with your shoulders and ankles, not sagging toward the floor or pushed up.
- Breathe steadily and stop the hold when the line breaks, rather than grinding on.
Common mistakes and how to fix them
Sagging hips
When the hips drop the lower back takes the load. Squeeze your glutes and brace your abs, or stop the hold.
Piking up
Raising the hips takes the work off the abs. Lower them until you are in a straight line.
Holding your breath
Holding your breath makes the hold feel harder and tires you sooner. Breathe slowly through the hold.
What Formanti checks on your plank
The clock starts when you have settled into position and stops when you leave it.
- Hold time: your goal (20, 30, 45, 60 seconds), or open. the longer you stay in good form, the better; time out of form is shown separately
Your position
What is judged the whole time you hold it, side-on to the camera.
- Body line: hips no more than 5% of your body length below, or 6% above, the straight line. one straight line from shoulders to ankles
What you hear and see when you are off
Lift your hips: your body line is sagging
The coach says: “Lift your hips”
On screen: Lift your hips: your body line is sagging.
Drill: Shorter holds with perfect form: 3 sets of 15 seconds, stopping the moment your hips drop, rather than one long sagging hold.
Lower your hips: they're piked up
The coach says: “Lower your hips”
On screen: Lower your hips: they're piked up.
Drill: Plank beside a mirror or film yourself from the side, and lower your hips until shoulders, hips and ankles line up.
Drills you can do alone
- Short holds with perfect form: three sets of 15 to 20 seconds, stopping the moment your hips move, before one long ragged hold.
- Knee planks or incline planks with your hands on a bench, to hold the line for longer while you build strength.
How to set up your phone
Phone on the floor 2 metres to your side, so your whole body from head to feet is in view. Forearm or straight-arm plank both work. Film from the side: the line of your body is judged from there. It all runs on your phone and nothing is uploaded.
Beta: It judges the straight line of your body from the side. It cannot see a sagging lower back, your neck position or whether your shoulders are over your hands. Guide values, new and not yet checked against real people.
Frequently asked questions
How long should I hold a plank?
Long enough that your form is still good at the end. For many people that is 20 to 60 seconds. A shorter hold in good form is worth more than a longer one that sags.
Where should I put the phone?
On the floor about two metres to your side, so your whole body from head to feet is in view. The line of your body is judged from the side.
More lifts to check
Deadlift · Squat · Push-up · Lunge · Overhead press · Bent-over row · Romanian deadlift · Bicep curl · Tricep extension · Lateral raise · Glute bridge · Pull-up · Dip · Sit-up · Jumping jack · Wall sit