Side Plank

Hold a lateral plank on one forearm, keeping your body in a straight line to engage the abdominals.

How to do the Side Plank#

1. Lie on your side and place your forearm on the ground with the elbow roughly under the shoulder.
2. Stack your feet (or place one slightly in front of the other) and lift your hips until your body forms a straight line from head to heels.
3. Tighten your core and keep your hips elevated to maintain a neutral spine.
4. Breathe steadily and hold the position for the planned duration.
5. Lower your hips with control to finish the set.

Muscles worked#

The side plank is the oblique exercise most people should be doing. Lying on one side and holding the hips off the floor means gravity is trying to fold you sideways, and the obliques on the bottom side — external and internal together — contract isometrically to stop it. The quadratus lumborum, a deep muscle between the ribs and pelvis, works alongside them, and the rectus abdominis and top-side obliques brace to keep the trunk from rolling.

The bottom hip is held up by its abductors, above all the gluteus medius, which is why the outer hip burns on long holds. The glutes keep the hips extended, and the side delt and rotator cuff of the supporting arm hold the shoulder in place. It should feel like a long band of tension down the side of the waist and into the outer hip; a burning shoulder means the position, not the core, is doing the work.

Common mistakes#

• Letting the hips sag toward the floor.
• Rotating the torso instead of keeping the body aligned.
• Shrugging the support shoulder toward the ear.
• Holding your breath during the hold.

Why it works#

It trains the sides of the trunk without twisting or bending the spine. Most oblique work involves rotation or lateral flexion, which is fine for healthy backs but not what everyone can tolerate. The side plank loads the same muscles isometrically in a neutral spine, which is why it is the standard lateral core exercise in back rehabilitation and a staple for anyone whose lower back complains about twists.

It also strengthens the gluteus medius, the muscle that keeps the pelvis level when you stand on one leg. Weakness there shows up as knees caving in squats, hips dropping when you run and a wobbly single-leg stance, and the side plank trains it under load without any equipment. Comparing your hold time left versus right is also a quick way to find an imbalance that is worth fixing.

Sets, reps and setup#

Three holds of 20-40 seconds per side with 30-45 seconds of rest between sides, three times a week. Hold with maximal tension rather than for as long as possible. Once 40 seconds is easy on both sides, make the variation harder rather than extending the time.

Setup

Lie on one side with the forearm on the floor and the elbow directly under the shoulder. Stack the feet, or place the top foot in front for more stability. Lift the hips until the body forms a straight line from head to heels, push the floor away with the forearm so the shoulder does not sink, and squeeze the glutes. Keep the hips stacked and the eyes forward.

Progression

Lift the top leg for a star side plank, which doubles the demand on the bottom hip and obliques. Rest the supporting hand on the floor for a straight-arm side plank, add a slow hip dip and lift, or place a weight on the top hip. If one side is much weaker, add an extra set on that side until the times match.

Variations#

• Star Side Plank Top leg and arm lifted, which increases the load on the bottom obliques and gluteus medius.
• Copenhagen Plank Top leg resting on a bench, shifting the work to the adductors of the inner thigh.
• Plank The front-facing version that loads the abs against extension instead of side bending.
• Side Bend Dynamic lateral flexion that moves the obliques through a range rather than holding them still.
• Pallof Press A standing anti-rotation hold that trains the obliques with a cable and an upright spine.

Side plank vs plank#

The standard plank resists extension: gravity pulls the hips down and the abs and glutes hold them up. It trains the front of the trunk and is the right choice for learning to brace and for building the stiffness that transfers to squats and presses.

The side plank resists lateral flexion, which shifts the work to the obliques, the quadratus lumborum and the outer hip. Those muscles get little from front planks and are usually the weak link in single-leg movements and in lower backs that ache on one side. Neither replaces the other; a basic core routine holds both, and most people find the side plank the harder of the two.