The obliques side elbow plank crunch is a bodyweight core exercise performed from a forearm side plank, driving the top knee up to the top elbow to train theobliques. Unlike a floor side crunch, the hips are already off the ground, so the bottom oblique holds the plank while the top oblique closes the waist against gravity. Both ends move toward each other: the knee comes up as the elbow comes down. Lifters program it as a core accessory after their main lifts, or inside a bodyweight circuit.
What Muscles Does the Obliques Side Elbow Plank Crunch Work?
- Primary: External and internal obliques of both sides
- Secondary: Quadratus lumborum, hip flexors, gluteus medius (side glute)
- Tertiary: Rectus abdominis, deltoids, serratus anterior
How Do You Set Up for the Obliques Side Elbow Plank Crunch?
Lie on your right side with your legs straight and stacked and your right elbow directly under your right shoulder, forearm flat and pointing away from your body. Press the forearm and the side of your bottom foot into the floor and lift your hips until your body forms one line from heels to head. Stack the hips, squeeze your glutes, and reach your left arm overhead in line with your torso.
How Do You Perform the Obliques Side Elbow Plank Crunch?
- Set the side plank with the hips lifted, shoulders and hips stacked, top arm reaching overhead.
- Exhale and drive your top knee up toward the ceiling side of your ribcage, keeping the hip from rolling back.
- Pull your top elbow down to meet the knee, bending the waist until the elbow and knee touch beside your ribs.
- Squeeze the top oblique for one count with the hips still high and the plank line held.
- Reverse both ends together, reaching the arm back overhead and lowering the leg onto the bottom one.
- Confirm the hips are still lifted and stacked, then repeat; finish the side before switching.
What Are the Key Form Cues?
- Close the waist, not the hip: think of shortening the side of your torso so the elbow and knee meet in the middle rather than folding at the hip crease.
- Hips stay high every rep: push the bottom forearm into the floor so the hip never sinks as the knee travels.
- Keep the bottom shoulder stacked over the elbow so the joint carries a vertical load.
- Feel the bottom oblique bracing while the top one contracts.
- Move the arm and the leg at the same speed so they arrive together.
What Are the Most Common Mistakes?
- Letting the hips drop as the knee lifts: the plank collapses and the bottom oblique quits, so reset the hip height between reps.
- Rolling the top hip backward: the body turns toward face-up and the movement becomes a front crunch, so keep the chest facing the wall.
- Reaching the elbow down without lifting the knee: only the arm travels and the waist never closes, so drive the knee first.
- Placing the elbow ahead of or behind the shoulder: the shoulder is loaded off its axis in a long side hold, so stack it directly underneath.
- Holding the breath through the rep: the brace breaks at the top and the hips wobble, so exhale as the knee rises.
What Are the Best Obliques Side Elbow Plank Crunch Variations?
- Side plank: the static hold with no crunch, the regression for building the position.
- Knee-down side plank crunch: the bottom knee on the floor shortens the lever.
- Side plank crunch with straight leg: the top leg stays long and lifts, a longer lever.
- Side plank crunch with reach through: the top arm threads under the torso, adding rotation.
- Side plank crunch on a bench: the bottom forearm on a bench raises the torso and lightens the hold.
How Do You Progress the Obliques Side Elbow Plank Crunch?
- Add a light ankle weight or hold a 5 pound plate on the top hip once bodyweight reps are clean.
- Work from 8 reps a side up to 15 before adding load.
- Add a set per week from 2 up to 4 while both sides match for reps and hip height.
- Hold the knee-to-elbow squeeze for three seconds, or lower the leg over three counts, instead of adding load.
How Should You Program the Obliques Side Elbow Plank Crunch?
Program it as a core accessory in the second half of a session, after squats, deadlifts or loaded trunk work. Two to three sessions a week is plenty. Work 2 to 3 sets of 8 to 15 reps a side with 30 to 45 seconds between sides. Pair it with a front plank or a dead bug so the trunk also trains against extension. Start each set on your weaker side.