Core · Anti-lateral flexion
Side Plank
The side plank is an isometric core exercise where you support your body sideways on one forearm and the edge of your feet, holding a straight line from head to heels. It trains the obliques and lateral hip to resist side bending, a demand the standard plank does not cover.
Also known as: Lateral plank, Side bridge, Side forearm plank
- Muscle group
- Core
- Movement pattern
- Anti-lateral flexion
- Type
- Isolation
- Equipment
- Bodyweight
- Difficulty
- Beginner
What muscles does the side plank work?
Primary movers
- Obliques
- Quadratus lumborum
Assisting muscles
- Gluteus medius
- Transverse abdominis
- Serratus anterior
- Deltoids
The side plank is an anti-lateral-flexion exercise. Gravity is pulling your hips towards the floor, which would bend your spine sideways, and the muscles down the side of your trunk contract to prevent it. The internal and external obliques on the down side do most of that work, with the quadratus lumborum assisting.
This is a genuinely different job from the one a front plank trains. A front plank resists extension, the spine arching backwards. A side plank resists lateral flexion. Both are anti-movement tasks, but they load different muscles, which is why the two complement each other rather than duplicating.
The gluteus medius on the down side works harder than most people expect. It sits on the outside of the hip and holds the pelvis level, and it is often the first thing to fatigue. A side plank that collapses at the hip rather than the ribs is usually a glute medius limitation.
The serratus anterior and the deltoid on the supporting side hold the shoulder stable and the shoulder blade against the ribcage. Letting the chest sink towards the floor between the shoulder and the arm removes that, which is why the hold should feel like actively pushing the floor away.
Because the movement is isometric and bodyweight-limited, it stops being challenging fairly quickly. Long holds mainly build tolerance to the burn; progressing to loaded or single-limb versions produces more.
How to do the side plank
Setup
- 1
Lie on your side with your legs straight and your feet stacked one on top of the other.
- 2
Place your supporting forearm on the floor with your elbow directly under your shoulder.
- 3
Keep your forearm pointing forward, perpendicular to your body.
- 4
Stack your hips and shoulders so your body is square rather than rotated.
- 5
Rest your top hand on your hip or extend it towards the ceiling.
Execution
- 1
Push your forearm into the floor and lift your hips until your body forms one straight line.
- 2
Squeeze the glute on your bottom side to hold the pelvis level.
- 3
Keep your hips stacked. Resist the tendency for the top hip to rotate forward.
- 4
Press your shoulder away from your ear so your chest does not sink towards the floor.
- 5
Breathe steadily through the hold rather than locking your breath in.
- 6
End the set when your hips start to drop, then repeat on the other side.
Common side plank mistakes
Letting the hips sag
The hips drift towards the floor as the obliques fatigue, which takes the load off the target muscles and puts it onto the shoulder and the side of the spine.
The fix: Drive your hips upward and squeeze the bottom glute. When you can no longer hold the line, the set is over. A strict 20-second hold beats a sagging 60-second one.
Rotating the hips forward
Twisting so the top hip and shoulder roll towards the floor. It shifts the position closer to a front plank and takes the obliques out of their anti-lateral-flexion role.
The fix: Stack the hips deliberately and think about keeping your chest and belly button facing straight out to the side. Practising against a wall gives immediate feedback.
Elbow out of position
Placing the supporting elbow ahead of or behind the shoulder, which loads the shoulder joint at an awkward angle and makes the hold considerably harder to maintain.
The fix: Set your elbow directly beneath your shoulder before you lift your hips, and check it each time you switch sides.
Holding your breath
Bracing by locking the breath in. It raises blood pressure unnecessarily and limits how long you can maintain a genuine brace.
The fix: Practise breathing shallowly into your ribs while keeping the side of your trunk tight. Bracing and breathing at the same time is a skill worth developing.
How many sets and reps?
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Core stability | 2–3 per side | 20–45 s | Bodyweight, strict | 45–60 s |
| Progression | 3 per side | 20–30 s | Weighted or leg raised | 60 s |
| Beginner | 2–3 per side | 10–20 s | Knees bent | 45 s |
Side planks are low-fatigue and can be trained several times a week, which makes them an easy addition to a warm-up or the end of any session. Always train both sides for the same duration, using your weaker side to set the target, side-to-side differences here are common and worth closing. Once you can hold a strict 45 seconds, progress by raising the top leg, adding a weight on your hip, or moving to a side plank with a hip dip rather than simply holding longer.
Running the side plank in your next block? Hercules logs every set, shows last session's numbers before you lift, and suggests when to add weight.
Get it on Google PlaySide Plank variations and alternatives
Knee Side Plank
EasierBending the knees and supporting on them shortens the lever substantially. The right regression if your hips sag within a few seconds.
Side Plank with Leg Raise
HarderLifting the top leg removes a support point and loads the gluteus medius on the bottom side considerably harder.
Weighted Side Plank
HarderA plate placed on the top hip adds direct load, which is the cleanest way to keep progressing once 45 seconds is comfortable.
Plank
AlternativeTrains anti-extension rather than anti-lateral-flexion. Complementary rather than competing. Most programmes should include both.
Russian Twist
AlternativeTrains the obliques through rotation rather than by resisting movement. A different quality, useful alongside isometric work.
Frequently asked questions
How long should I hold a side plank?
Twenty to forty-five seconds per side, held strictly. Once you can manage a genuine 45-second hold with level hips, adding time yields diminishing returns. You are training tolerance to the burn rather than building strength. Progress by raising the top leg or adding a weight on your hip instead.
What muscles does the side plank work?
Mainly the obliques and quadratus lumborum on the supporting side, which resist your hips being pulled towards the floor. The gluteus medius works hard to keep the pelvis level, and the shoulder stabilisers and serratus anterior hold the supporting arm position.
Is the side plank better than the regular plank?
Neither is better, they train different things. A front plank resists the spine extending; a side plank resists it bending sideways. Both are demands the trunk faces in real lifting and daily movement, so a complete core programme includes both rather than picking one.
Why is one side of my side plank so much weaker?
Side-to-side differences are extremely common, usually from habitual asymmetries in how you sit, stand and carry things. Train both sides for the same duration, set by whatever your weaker side can manage, and the gap generally narrows within a few weeks.
Do side planks burn love handles?
No, spot reduction is not how fat loss works. Side planks strengthen the obliques underneath, but where your body loses fat is determined by overall energy balance and genetics rather than by which muscle you train. Strengthening the obliques is worth doing on its own merits, just not as a targeted fat-loss method.
Hercules tracks every side plank you log, shows you last session's numbers before you lift, and flags when your progress stalls.
Get it on Google Play