What the plank trains, and where it fits
The plank is an anti-extension exercise. Gravity tries to pull your hips towards the floor and arch your lower back, and your trunk muscles stop it. The rectus abdominis, the long muscle down the front of your stomach, does much of that work, helped by the deep muscle that wraps around your middle and by the obliques at your sides. Your glutes keep the pelvis level, and your shoulders stop your chest sinking between your arms. Nothing moves, and that is the point: much of your trunk's job in the gym is holding still while your arms and legs work.
That makes the plank a sensible first core exercise and one worth keeping, usually as a short block at the end of a session so your trunk is fresh for squats and deadlifts. It will not flatten your stomach on its own; how your waist looks depends far more on overall body fat than on any one exercise. The core training guide shows how holds, carries and the big lifts fit together.
Getting into position
- Kneel on a mat or a clear patch of floor and set your forearms down, elbows directly under your shoulders. Keep the forearms parallel, or clasp your hands loosely if that sits better on your shoulders.
- Step your feet back one at a time until your legs are straight, toes tucked and feet about hip-width apart. Wider feet make the hold easier; feet together make it harder.
- Lift your knees so your body forms one line from head to heels. If there is a mirror nearby, check it side-on.
- Tuck your pelvis slightly, as if tightening a belt by one notch, and squeeze your glutes. You should feel your lower stomach switch on.
- Pick your level. If you cannot hold the full version for twenty seconds without your hips dropping, start with your knees down or your forearms on a bench, and return to the floor when that becomes easy.
Holding a good plank
- Brace before you start the clock: breathe in, then tighten your stomach as though someone were about to poke it.
- Push the floor away through your forearms, so your upper back fills out instead of sinking between your shoulder blades.
- Keep your glutes and thighs tight, and pull your elbows gently towards your toes without letting them slide. That small tension makes the plank noticeably harder.
- Breathe in short, steady breaths behind the brace, eyes on the floor just ahead of your hands.
- End the set when your hips sag or pike up, or when you can no longer breathe without losing the brace, whatever the timer says.
Hold the brace, not your breath. If your face reddens and you start to gasp, end the hold and make the next one shorter. The breathing and bracing guide teaches the same brace you use under a heavy bar. If planks cause pain in your back, shoulders or elbows, stop and get it checked by a doctor or physiotherapist.
Plank mistakes to fix first
| Mistake | What it looks like | The fix |
|---|---|---|
| Sagging hips | The lower back dips towards the floor | Squeeze the glutes, draw the ribs down and shorten the hold |
| Hips piked high | The body makes a tent instead of a line | Lower the hips until shoulders, hips and heels line up; check side-on |
| Head hanging or craned | The chin drops to the chest, or the head lifts to look forward | Keep the neck long and look at the floor just ahead of your hands |
| Holding the breath | A red face and a gasp at the end of the hold | Short breaths behind a firm stomach; end the set if you cannot manage both |
| Sinking between the shoulders | The shoulder blades pinch together and the chest drops | Push the floor away until the upper back is slightly rounded and full |
| Chasing the clock | Long holds where the second half is done in poor shape | Use shorter, harder holds, and progress the version rather than the time |
Side planks, shoulder taps and other versions
The front plank resists arching. Its variations add resistance to leaning sideways or twisting, or simply more load, so between them they cover most of what your trunk does when you lift.
Side plank
Lie on one side with your forearm under your shoulder and lift your hips until your body forms a straight line from head to feet, feet stacked or staggered for balance. It trains the obliques and the muscles at the side of your hip to stop you sagging sideways. Start with your knees bent on the floor if the full version is too hard, and give both sides the same work.
Plank with shoulder taps
From a high plank on your hands, lift one hand to touch the opposite shoulder, put it down and repeat on the other side. Taking a hand away makes your trunk resist twisting, so aim for hips that barely sway. Widen your feet to make it easier, and slow the taps down to make it harder.
Weighted plank
Once a one-minute front plank feels easy, a partner can lay a weight plate across your upper back, between the shoulder blades, never on the lower back. Keep these holds to about twenty to thirty seconds, and have the partner lift the plate off at the end.
How long should you hold a plank?
For most people, sets of twenty to forty-five seconds with a perfect line do more than one long, shaky hold. Once three sets of about forty-five seconds feel comfortable, make the plank harder rather than longer: bring your feet together, move your elbows a little further forward, or switch to one of the versions above.
If the floor is crowded or planks bother your elbows, a dead bug does a similar job lying on your back, and a Pallof press on the cable machine trains your trunk to resist twisting while you stand.
Sets, hold times and progression
| Goal | Sets × reps | How hard |
|---|---|---|
| Learning the position | 3 × 15–20-second holds | End each hold while your line is still perfect |
| Building trunk endurance | 3 × 30–45-second holds | Stop a few seconds before your hips want to drop |
| Moving to harder work | 3–4 × 20–30-second holds | A harder version, such as a weighted or long-lever plank, with the same clean line |
Rest thirty to sixty seconds between holds. A front plank followed by a side plank on each side makes a quick circuit to finish a session.
Two or three short core blocks a week, after your main lifts, suit most people. When the standard hold stops being a challenge, the next step up in anti-extension work is the ab wheel rollout.
Planks at RPM
A plank needs nothing more than a patch of floor or a mat, so you can hold one in either section. RPM's photos show a turf lane in the functional area and cable towers on the main floor, where the next steps, Pallof presses and cable chops, are done. A personal training session is a quick way to have someone check your line from the side, and if you would rather work with a woman coach, see female personal training.
Questions, answered.
Is a plank better than crunches or sit-ups?
They do different jobs. Crunches and sit-ups train the trunk to bend forwards; the plank trains it to resist bending backwards. A balanced core block can include both, with planks as the base.
Plank or push-up: which should I do?
Both. A push-up is a moving plank: your trunk holds the same straight line while your chest, shoulders and triceps lower and press your body. If your hips sag during push-ups, practising planks helps you hold that line.
What is a reverse plank?
A plank facing the ceiling. Sit with your legs straight and hands behind your hips, then lift your body into a line from shoulders to heels. It works the glutes, hamstrings and the backs of the shoulders more than the stomach.
What can I do instead of a plank?
If the full plank is too hard, use a knee plank or rest your forearms on a bench. For a different anti-extension exercise, the dead bug works lying down. If planks cause pain, or you are pregnant or postnatal, ask a doctor, physiotherapist or midwife what suits you before continuing.