The side plank is a static hold for your obliques and the side of your core: it teaches you to keep your body straight when the load comes from the side.
1Starting positionStart2End positionFinish
Setup
Lie on your side, elbow under your shoulder, forearm on the floor. Legs straight, feet stacked or one in front of the other. Lift your hips until your body is a straight line.
Execution
Lie on your side, prop yourself up on one forearm, elbow under your shoulder, feet stacked.
Raise your hips until your body forms a straight line from head to heels, and hold for the set time. Repeat on the other side.
Common mistakes
Hips sagging toward the floor — lift them, heels to head in one line.
Hips drifting back — keep your hips in line with your torso.
Shoulder creeping up to your ear — elbow right under the shoulder, push the floor away.
Only training one side — hold both sides for the same time.
Not sure about your form? Send me a video of a set — I'll take a look and tell you what to fix first.