Side plank
An isometric hold that trains the obliques and lateral trunk stability.
What it is
An isometric hold on one forearm and the side of the foot, with the body in a straight line. It trains the muscles that resist sideways bending — the obliques and quadratus lumborum — which the standard plank barely touches.
Muscles worked
Primary: Obliques. Secondary: Gluteus medius, Quadratus lumborum, Rotator cuff.
How to perform it
- Lie on your side with your forearm on the floor, elbow directly under your shoulder.
- Stack your feet, or stagger them for more stability, and set your top hand on your hip.
- Lift your hips off the floor so your body forms a straight line from ankle to shoulder.
- Hold, breathing normally, then lower under control and repeat on the other side.
Common form faults
- Hips sagging towards the floor. Squeeze the glutes and push the bottom shoulder away from the floor; shorten the hold rather than letting the position collapse.
- Rotating so the chest faces the floor. Keep the shoulders and hips stacked; a mirror or a phone camera is useful for checking.
- Holding your breath. Breathe steadily throughout. A brace you cannot breathe through is not one you can use anywhere else.
Programming
Short, quality holds beat long, sagging ones. Progress by adding time, then by raising the top leg or arm, then by adding external load — not by grinding out ever-longer holds in a broken position.
Plan your training
Variations & substitutions
Frequently asked questions
- How long should I hold a side plank?
- Long enough to be challenging with a perfect line, which for most people is far shorter than they expect. Multiple short high-quality holds beat one long collapsing one.
- My shoulder hurts — what am I doing wrong?
- Usually the elbow is not directly under the shoulder, or you are sinking into the joint. Reposition the elbow and actively push the floor away.
Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.
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