Plank

What is the Plank?

The plank is an isometric core exercise: you hold a rigid, straight-line position on your forearms and toes rather than moving through reps. It trains the abs and the deep trunk to resist your spine sagging or twisting (the same anti-extension strength that protects your back under heavy lifts), and needs no equipment at all.

Muscles worked

Primary: Abs

The abs (the rectus abdominis and the deep transverse abdominis) work isometrically to keep the hips from sagging and the spine from over-extending.

Stabilizers

The glutes, obliques, and shoulder stabilisers all contribute to holding the straight, rigid line from heels to head.

How to perform the Plank

1. Set your forearms on the floor directly under your shoulders, elbows at ninety degrees, with feet together or hip-width behind you.
2. This is an anti-extension hold: brace so the load of gravity cannot bow your lower back downward toward the floor.
3. Tuck the pelvis slightly, squeeze the glutes, and draw the ribs down so the body forms one straight line from heels to head.
4. Push the forearms and toes into the floor to create full-body tension, and pull the elbows back toward your feet without moving them.
5. Breathe in shallow, controlled breaths through the brace rather than holding your breath for the duration of the hold.
6. Hold the line for the target time, then end the set the moment the hips start to sag or pike, lowering the knees down under control.

Suggested working range: 30–60 reps. Default progression: double progression.

Mechanics

A static isometric hold, not a rep-based movement: no joint moves through a range, and the core simply resists gravity trying to break your straight-line position. That anti-extension demand is exactly what carries over to bracing under squats and deadlifts.

Form cues

• •Set the elbows under the shoulders and form a straight line from heels to head. No sagging hips, no piking up.
• •Squeeze the glutes and brace the abs as if about to take a punch; the plank is an active hold, not a rest.
• •Tuck the pelvis slightly so the lower back doesn’t arch and dump the load onto the spine.
• •Breathe steadily throughout rather than holding your breath.

Common mistakes

• •Letting the hips sag toward the floor so the lower back bows into extension under gravity.
• •Piking the hips up toward the ceiling to take tension off the abs and rest in the shoulders.
• •Holding the breath for the whole set instead of breathing in small controlled breaths through the brace.
• •Setting the elbows too far in front of the shoulders, which shifts the load off the abs and onto the shoulders.

Variations & alternatives

• •Weighted plank: a plate on the back adds load once long holds get easy.
• •RKC plank: a shorter, maximally-braced hold that raises intensity without adding time.
• •Side plank: rotates the emphasis to the obliques and lateral core.
• •Ab-wheel rollout: a moving anti-extension progression once the plank is easy.

Crunch

Abs · Bodyweight

Cable Crunch

Abs · Cable

Hanging Leg Raise

Abs · Bodyweight

Machine Crunch

Abs · Machine

Decline Crunch

Abs · Bodyweight

Programming: sets, reps & when to use it

The plank is measured in time, not reps: the library’s 30–60 range refers to seconds per hold. Rather than chasing ever-longer holds, keep them in that window with a hard full-body brace and progress by adding load (a plate on the back) or moving to a harder variation. A few quality holds after your main work is enough.

Frequently asked questions