Plank

Also known as: Front plank

An isometric hold that trains the core to resist extension and stay rigid.

What it is

An isometric exercise where you hold a straight-body position on your forearms and toes. It trains the core's main job — resisting movement (here, anti-extension) to keep the spine stable — rather than crunching.

Muscles worked

Primary: Core (rectus abdominis, deep core). Secondary: Shoulders, Glutes.

How to perform it

  1. Set your forearms on the floor under your shoulders, legs extended behind you on your toes.
  2. Form a straight line from head to heels, tucking the pelvis slightly so the lower back doesn't sag.
  3. Brace the abs and squeeze the glutes, keeping the neck neutral.
  4. Hold for time, breathing steadily, and stop when your form starts to break.

Common form faults

  • Hips sagging toward the floor. Tuck the pelvis and squeeze the glutes and abs to keep a straight line; shorten the hold if you can't hold position.
  • Hips piking up into an easy tent shape. Bring the hips down in line with the shoulders and heels so the core actually works.

Programming

Train quality over marathon holds — once you can hold a solid position for around 45–60 seconds, add difficulty (weight, longer lever, reaching) rather than just chasing minutes.

Variations & substitutions

Frequently asked questions

How long should I hold a plank?
Long holds have diminishing returns. Once you can hold a strong, straight position for around a minute, it's more useful to make it harder — add weight, extend the lever, or add reaching movements — than to keep extending the time.
Why do I feel it in my lower back?
That usually means the hips are sagging and the back is taking over. Tuck the pelvis, squeeze the glutes and abs, and shorten the hold until you can keep a flat, braced line.

Written and reviewed by Mathew Beale MSc Biotechnology, University of Reading.

Last reviewed: