Side Plank: How to Do It, Muscles Worked and Benefits

The side plank is an isometric hold performed on one forearm with your body turned sideways, and it is the most under-used core exercise there is. Where a front plank stops your lower back sagging, a side plank stops your body folding sideways, which is a job handled by muscles most people never train directly. It builds the obliques, the quadratus lumborum and the glute medius all at once, needs no equipment and takes up about a metre of floor. Here is how to do it properly, what it works, and how to progress once the basic hold gets easy.

How to do a side plank

All you need is a floor and ideally a mat under your elbow.

1. Lie on your side. Lie down on your right side with your legs straight and stacked, one foot on top of the other. Prop yourself on your right forearm with the elbow directly under your shoulder and the forearm pointing forwards.
2. Set your body line. Stack your hips and shoulders so you are genuinely on your side, not rolled slightly towards the floor or the ceiling.
3. Brace and lift. Squeeze your glutes, tighten your abs and push your hips up off the floor until your body forms a straight line from your ear through your hips to your ankles.
4. Push the floor away. Drive your forearm down and lift your ribcage away from the ground so your shoulder does not sink. Your top arm can rest on your hip or reach straight up.
5. Breathe and hold. Breathe steadily rather than holding your breath. Hold for your target time with the line intact.
6. Lower under control. Set your hip back down slowly, rest, then repeat on the other side.

Muscles worked

• Obliques. The external and internal obliques on the down side are the primary movers, working isometrically to stop your hips dropping towards the floor.
• Quadratus lumborum. This deep muscle running between your pelvis and your lower ribs is hard to reach with most exercises. Research on core exercise tolerability found the lateral plank activates the quadratus lumborum and the abdominal muscles well while generating relatively low spinal load (core muscle exercises in chronic low back pain).
• Transversus abdominis. The deep corset-like abdominal layer. Ultrasound comparisons of common trunk exercises found side plank variations produced the greatest increase in relative abdominal muscle thickness of the exercises tested (comparison of core stability exercises and muscle thickness).
• Gluteus medius. The bottom hip works hard to keep the pelvis lifted, which is why the side plank doubles as hip stability training for runners.
• Shoulder stabilisers. The serratus anterior and rotator cuff of the supporting arm hold the shoulder blade in place against your ribcage.
• Adductors and lats. Both assist in holding the line, particularly in the harder variations.

Trunk muscle activity varies quite a bit between side bridge set-ups, which is why the variations further down are worth cycling through rather than doing the same hold forever (comparison of trunk muscle activity during modified side bridge exercises).

Benefits

• It trains a pattern nothing else does. Resisting sideways bend, known as anti-lateral flexion, is a genuine gap in most training programmes. The side plank fills it directly.
• It builds the waist muscles you actually use. Carrying shopping in one hand, swinging a golf club or racket, changing direction when running: all of these depend on the side of your trunk holding firm.
• Low spinal load. You get high muscle activation without heavy compression through the spine, which makes it a sensible option for people who find loaded core work uncomfortable.
• It exposes left to right imbalances. Almost everyone is weaker on one side. The side plank tells you which, and lets you fix it by adding a set on the weaker side.
• No kit, no space, no noise. Perfect for a small flat, a hotel room or the end of a home workout. All you really need is a yoga mat.
• It supports the strength habit. Core work counts towards the muscle-strengthening activity the NHS recommends on at least two days a week.

Common mistakes

Hips sagging. The single most common fault. The moment your hips drop, the obliques stop doing the work. Set a timer for a shorter hold and finish it in a straight line rather than grinding out a long, collapsing one.

Rolling forwards. If your top shoulder drifts towards the floor you turn the exercise into a wonky front plank. Stack the shoulders and hips squarely.

Sinking into the shoulder. Letting your bodyweight hang on the supporting shoulder joint is uncomfortable and unstable. Actively press down through the forearm.

Elbow out of position. The elbow should be directly under the shoulder. Too far forward or back and the joint takes an awkward angle.

Holding your breath. Bracing does not mean stopping breathing. Take shallow, steady breaths while keeping the abs tight.

Only training the strong side. Do both sides for the same time even if one feels much harder, and consider adding an extra set on the weaker side for a few weeks.

Variations

Easier

• Kneeling side plank. Bend your knees to 90 degrees and support on your knee rather than your foot. This shortens the lever and cuts the difficulty roughly in half. The right place for most beginners to start.
• Wall side plank. Stand at arm's length from a wall, forearm against it, and press your hips forward into a standing side plank. Almost no spinal load, useful if the floor version bothers your shoulder.
• Staggered feet. Put the top foot on the floor in front of the bottom one for a wider, more stable base.

Harder

• Straight arm side plank. Support on your hand instead of your forearm. More shoulder stability demand and a longer lever.
• Side plank with top leg raise. Lift the top leg and hold. Brutal on the glute medius of both hips.
• Side plank with hip dips. Lower your hip until it just brushes the floor, then drive it back up. Turns the hold into a dynamic oblique exercise.
• Feet elevated side plank. Stack your feet on a bench, plyo box or step to raise the difficulty sharply.
• Weighted side plank. Rest a small plate or kettlebell on your top hip once bodyweight holds are easy.
• Side plank on a ball. Forearm or feet on an exercise ball adds an instability challenge that makes even a short hold hard work.
• Copenhagen plank. Top leg on a bench, bottom leg hanging. Punishing for the adductors and a favourite in football and running injury prevention work.

Sets and reps

Progress on quality first, then time, then difficulty.

• Beginner: 3 sets of 15 to 20 seconds each side, kneeling if needed. Rest 30 seconds.
• Intermediate: 3 sets of 30 to 45 seconds each side, full version. Rest 45 seconds.
• Advanced: 3 sets of 30 to 45 seconds each side with a harder variation such as top leg raised, feet elevated or weighted.

Two or three sessions a week is plenty. Once you can hold a clean 60 seconds on both sides, stop adding time and pick a harder variation instead, because very long holds mostly train tolerance for discomfort rather than strength. Pair the side plank with a front plank and a rotational movement such as the Russian twist and you have a complete, five minute core circuit.

Recommended reads

1. Plank: how to do it and how long to hold
2. Russian twist technique guide
3. Hanging leg raise guide
4. The best yoga mat in the UK
5. The best ab roller in the UK