The obliques side elbow plank crunch is a bodyweight core exercise that layers a knee-to-elbow crunch on top of a side plank hold. Supporting your weight on one forearm forces the obliques and shoulder stabilizers to work isometrically while the crunching leg adds a dynamic lateral flexion component that directly targets the obliques. It is more demanding than a standard side plank because the body never fully settles into a static hold.
Muscles Targeted
- Primary: Obliques (internal and external)
- Secondary: Rectus abdominis, shoulder stabilizers (deltoids, rotator cuff)
- Tertiary: Glutes, hip abductors
Starting Position
Lie on your side with your legs stacked and knees slightly bent. Prop yourself up on your bottom forearm so the elbow sits directly beneath the shoulder, forearm perpendicular to your body. Lift your hips off the floor so your body forms a straight line from shoulder to knee, and extend your top arm straight overhead in line with your torso.
Execution Steps
- Establish the side plank by lifting your hips until your shoulder, hip, and knee are aligned
- Brace your obliques on the supporting side before initiating any movement
- Bring your top knee up and forward toward your chest while simultaneously bending your top elbow down
- Crunch your elbow and knee together at the side of your torso, contracting the obliques
- Extend back out to the straight side plank position under control, resisting the urge to drop your hips
- Repeat for the desired number of reps, then lower and switch to the other side
Form Cues
- Keep the hips lifted throughout: Dropping the hips between reps removes the isometric oblique demand
- Stack the shoulders and hips: Rotating forward or backward reduces oblique isolation and shifts load to the shoulder
- Crunch from the side, not the front: The knee and elbow should meet at your side, not in front of your body
- Keep the supporting elbow fixed under the shoulder: A collapsed or shifted elbow destabilizes the whole position
- Move with control on both the crunch and the return: Fast, jerky reps favor momentum over oblique tension
Common Mistakes
- Letting the hips sag: This removes tension from the obliques and shifts stress into the lower back; keep a straight line throughout.
- Rotating the torso forward: Twisting toward the floor turns the exercise into a hip flexor movement instead of an oblique one; keep the shoulders stacked.
- Rushing the crunch: Fast, bouncing reps rely on momentum rather than muscular contraction; slow the tempo down.
- Sagging the supporting shoulder: Letting the shoulder collapse toward the ear strains the joint; keep it packed down and stable.
- Overextending the knee: Kicking the leg straight out at the bottom of the rep swaps oblique tension for hip flexor work; keep it under control.
Variations
- Knee-supported side elbow plank crunch: Bend the bottom knee for a reduced-use entry point for beginners
- Weighted side elbow plank crunch: Hold a light dumbbell in the top hand for added resistance
- Side plank with hip dip: Removes the crunch and adds a pulsing hip lower/lift for a more isometric-dominant oblique challenge
- Side plank rotation (thread the needle): Adds a reach-under rotation instead of a knee crunch for a more dynamic oblique twist
Tips for Progression
- Master the static side plank first: Build to a 30-45 second hold before adding the crunch
- Increase reps per side: Progress from 8-10 to 15+ controlled reps before adding load
- Add external resistance: Hold a light weight in the top hand once bodyweight reps are easy
- Slow the eccentric: Extend back out over 2-3 seconds to increase time under tension
Training Notes
Program this exercise 2-3 times per week as part of a core circuit, using 2-3 sets of 8-12 reps per side with 30-45 seconds of rest between sides. It works well paired with anti-rotation and anti-extension core work in the same session, since it trains oblique strength through both isometric holding and dynamic contraction.