Cross-Body Crunch
A floor crunch with a diagonal: feet flat, knees bent around 60 degrees, and each rep drives one shoulder across toward the opposite knee while that knee comes to meet it. The diagonal is what recruits the obliques, and it is also what most people fake by swinging an elbow.
Own the movement
Set up first, then execute. Every cue below is something you can check on your next set.
Before the first rep
- Lie on your back with your feet flat and your knees bent to roughly 60 degrees — closer to your hips than a standard crunch.
- Rest your fingertips lightly behind your ears. Never lace them and never pull.
- Press your lower back into the floor and keep it there for the entire set.
- Point your elbows out wide so you cannot close them in and drag your head forward.
Every rep
Breathing & tempo — Exhale as you curl and rotate, inhale on the way down. Two seconds up, one to two seconds squeezed, two seconds down — no bouncing off the floor between sides.
Sets, reps & load
Where to start, and what to change when it stops being hard.
Bodyweight. You can hold a 2-5 kg plate against your chest once 20 controlled reps a side is easy, but the arm position gets awkward — slowing the tempo to a three-second lower with a two-second squeeze is usually the better progression. When even that stops being hard, move to a loaded rotation or a decline oblique crunch instead.
What goes wrong
The errors that show up most often, and the cue that fixes each one.
Cross your arms over your chest instead of putting your hands behind your head. With no elbow to swing, the only way to reach is to actually rotate and lift the torso.
Rest your fingertips behind your ears with the elbows wide, and keep a tennis-ball gap between your chin and your sternum through every rep. If your neck aches the next day, that gap closed.
Take two seconds up, one second squeezed, two seconds down, and cap the set at 15 reps a side. If that feels easy, hold the squeeze for three seconds rather than adding speed.
Actively drive the knee toward the shoulder on each rep so both ends of the torso close in. If the foot never leaves the floor, you are doing half the exercise.
Why bother
The external oblique on one side and the internal oblique on the other run in opposing diagonals. Curling the right shoulder toward the left knee lines the movement up with that diagonal, so both fire alongside the rectus abdominis instead of just holding position.
The elbow is a decoy. It sits at the end of a long arm and can travel a foot across your body while your ribcage never moves at all. What counts is whether your right shoulder blade leaves the floor and rotates toward your left hip — the elbow only comes along for the ride.
Where it fits
Bodyweight finisher, two or three times a week, or a warm-up set before loaded ab work to get the obliques switched on. It needs nothing but floor space, which makes it a reasonable travel option — but it is not a substitute for something you can progressively load once 20 controlled reps a side is easy.
If this one isn't it
No kit, too hard, or too easy — here's where to go instead.
Same job, different kit
Start here instead
Asked and answered
Is this better than a bicycle crunch?
They train the same diagonal. The difference is pace: the bicycle is a continuous alternating movement that most people rush, while the cross-body crunch has a clear start and finish per rep, so a pause and a squeeze are easy to enforce. If you struggle to slow the bicycle down, use this one.
Will this get rid of my love handles?
No. Training a muscle does not burn the fat sitting on top of it — spot reduction has been tested repeatedly and does not happen. Building the obliques makes them firmer and more defined once bodyfat comes down, and bodyfat comes down through diet and total activity.
My neck hurts during these. What am I doing wrong?
Almost certainly pulling on your head. Your neck flexors fatigue long before your abs do, and once they give up the hands take over. Fix it by resting your fingertips behind your ears rather than clasping, keeping the elbows wide, and holding a fist-sized gap under your chin. If it persists, cross your arms on your chest and shorten the range.
How do I make this harder without equipment?
Slow it down and extend the lever. Take three seconds to lower, hold the top squeeze for three, and straighten the non-working leg out along the floor so it cannot help. Those three changes make a set of ten harder than a rushed set of thirty.