Cross-body Knee Crunch
The cross-body knee crunch is a bodyweight exercise targeting the obliques through a diagonal knee drive from a plank position. The cross-body movement pattern challenges rotational core stability and hip flexor strength simultaneously.
How to do it
- Begin in a high plank position with hands under your shoulders and body straight.
- Bring your right knee across your body toward your left elbow.
- Return your foot to the starting position.
- Repeat on the other side, bringing your left knee toward your right elbow.
- Continue alternating for the desired number of repetitions.
Form cues
- Keep your wrists stacked directly beneath your shoulders.
- Brace your core as if preparing for a gentle tap to the stomach.
- Drive your knee diagonally across your body toward the opposite elbow.
- Exhale smoothly as you twist and drive the knee.
- Lower your foot back to the starting plank with control.
Breathing: Exhale as you drive your knee across your body; inhale as you return to the starting plank position.
Common mistakes
- Sagging your hips toward the floor, which strains your lower back and reduces core engagement.
- Rushing through the movement using momentum rather than controlled core strength.
- Lifting your hips too high into the air, which shifts the work away from your abs and obliques.
Muscles worked
Primary: obliques. Secondary: abs, hip flexors, shoulders.
Suggested sets & reps
Get fitter
3 sets x 10-14 reps, rest 60 seconds between sets
Lose weight
3 sets x 12-16 total reps, rest 45 seconds between sets
Build muscle
3 sets x 8-12 slow reps per side, rest 60 seconds between sets
Easier, harder & alternatives
Make it harder
Take care if…
- If you feel wrist discomfort, ease off or perform the movement with hands elevated on a sturdy surface.
General educational guidance, not medical advice. Stop on sharp pain and check with a qualified professional if unsure.
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Start free →Frequently asked questions
What muscles does the cross-body knee crunch work?
It primarily targets your obliques and deep core stabilizers, while also engaging your shoulders, abs, and hip flexors.
Should I feel this in my lower back?
No. If you feel it in your lower back, your hips are likely sagging. Engage your glutes and brace your core more firmly.
Can I do this exercise on my knees if planks are too hard?
It is best to start with standard regressions like a plank knee to chest or a kneeling variation until your core strength builds up.