Cross-Body Crunch
The cross-body crunch is a floor exercise where you curl your shoulder up and rotate it toward the opposite knee, working your abs and obliques in the same rep. It's a natural next step once a straight crunch feels easy, since the twist adds a rotational demand a standard crunch doesn't ask for. All you need is a mat and a few feet of floor.
Why it works
A straight crunch mostly works the muscle running down the front of your torso, but your obliques, which wrap around your sides, need a rotational movement to actually work hard. Bringing your elbow across toward the opposite knee asks your torso to flex and rotate at the same time, which is exactly the combined motion your obliques are built for. Because you alternate sides, each rep also trains your core's ability to stabilize one side while the other one moves.
Set up
- Lie on your back with your knees bent and feet flat on the floor.
- Place your hands lightly behind your head with elbows out wide, without lacing your fingers or pulling on your neck.
- Lift both feet off the floor so your shins are roughly parallel to the ground, or keep them planted if you'd rather start simpler.
How to do it
- Curl your shoulders off the floor and rotate your torso to bring one elbow toward the opposite knee.
- Extend the other leg out as you twist, so the working knee and the reaching elbow meet somewhere in the middle.
- Pause briefly at the point of closest contact, then uncurl back to the floor with control.
- Repeat on the other side, alternating one rep per side for the full set.
- Keep your lower back gently pressed toward the floor throughout, rather than arching as you switch sides.
Form cues
- Lead with your ribs rotating, not just your elbow reaching.
- Keep your neck relaxed; your hands support the head, they don't pull it.
- Exhale hard on the twist to help your obliques finish the rep.
- Move at a steady tempo, not a bicycle-kick speed.
Breathing: Exhale sharply as you curl and twist toward the opposite knee, and inhale as you uncurl back down.
Common mistakes
Pulling on the neck with laced fingers to force the crunch higher.
Fix: Keep your hands open behind your head for light support only; let your abs do the lifting, not your arms.
Moving so fast the rep turns into a bicycle-kick blur.
Fix: Slow down enough to actually feel the elbow and knee meet each time; speed here trades muscle tension for momentum.
Only rotating the arm while the torso stays flat on the floor.
Fix: Focus on rotating through your ribs and shoulder, not just swinging your elbow sideways.
Letting the lower back arch off the floor as you switch sides.
Fix: Keep a gentle brace in your abs between reps so your spine doesn't rock as you alternate.
How to program it
- Bodyweight ab work like this recovers fast, so most people can do it 3 to 4 times a week without it interfering with the rest of their training.
- 2 to 3 sets of 12 to 20 total reps, alternating sides, is a reasonable target once the movement feels controlled.
- It works well at the end of a session as a finisher, or paired with a plank for a short core circuit.
- Once 20 controlled reps feels easy, add a slow two-second pause at the top of each twist before adding any external load.
Safety notes
- Stop if you feel the movement in your neck instead of your abs; that usually means your hands are pulling instead of resting.
- Keep the twist controlled rather than snapping through it, especially if you have any lower back sensitivity.
Exercise profile
- Force
- Pull
- Mechanics
- Compound
- Category
- Strength
Frequently asked questions
How many reps of cross-body crunches should I do?
Aim for 2 to 3 sets of 12 to 20 total reps, alternating sides. Slow, controlled reps beat a higher count done in a rush.
What's a good bodyweight substitute if cross-body crunches bother my neck?
Try oblique crunches with your hands resting lightly on your chest instead of behind your head, so there's nothing to pull with.
Cross-body crunch vs bicycle crunch: what's the difference?
They target the same muscles, but the bicycle crunch keeps both legs moving continuously at a faster pace, while the cross-body crunch is slower and lets you pause and squeeze at each twist.
Why do I feel cross-body crunches in my neck?
Your hands are likely pulling the head up instead of just supporting it. Keep your elbows wide, your fingers unlaced, and let your abs, not your arms, do the lifting.