Muscles worked
Abs, obliques, hip flexors.
Why bicycle crunches work
The rotation from elbow to opposite knee specifically trains the obliques' role in twisting the torso, a movement most standard crunches don't touch at all. Combining that rotation with the pedalling leg motion is why electromyography studies on ab exercises consistently rank it among the highest for oblique activation.
How to do bicycle crunches
- Lie on your back, hands lightly behind your head, knees up.
- Lift your shoulder blades off the floor.
- Bring one elbow toward the opposite knee while extending the other leg.
- Switch sides in a smooth pedalling motion.
- Keep the movement controlled, not rushed.
What you should feel
Work through the front and sides of the abdomen. If you mainly feel it in your neck, you are pulling on your head — rest your fingertips behind your ears instead of lacing them, and lead with the shoulder rather than the elbow.
Form tips
- Rotate from your ribcage, not your arms.
- Keep your lower back pressed gently into the floor.
- Go slow for more control and tension.
Slow beats fast, every time
Bicycle crunches are among the most commonly rushed exercises in existence. Performed at speed they become a torso-swinging, neck-yanking cardio movement that barely challenges the abdominals; performed slowly they are genuinely difficult and one of the better exercises for the obliques.
The rotation should come from your ribcage turning toward the opposite knee, not from your elbow travelling across your body. Those look similar and are not the same thing. Try leading with your shoulder rather than your elbow — it forces the rotation to originate where it should.
Keep your fingertips resting lightly behind your ears rather than laced behind your head. Laced hands invite you to pull on your neck when the set gets hard, which is where most of the neck complaints associated with this exercise come from. Your neck should stay in a neutral position with a fist-sized gap under your chin.
Keep your lower back pressed toward the floor throughout. If it arches away, your legs are too low — raise them higher until you can maintain contact. Extending the leg out toward the floor is the hardest part of the rep, and lowering it further than you can control is the point at which the hip flexors take over from the abdominals and the lower back starts arching.
Sets and reps
3 sets of 15–20 reps per side.
Programming it into your week
Two to three sets of ten to twenty reps per side, at the end of a session. These are a flexion and rotation movement, so pair them across the week with an anti-extension exercise such as the plank rather than doing only crunching work.
How to progress
Slow down before you add reps. Most people perform these far too fast, using momentum and a swinging torso to move through the range rather than the abdominals. A controlled two-second cycle per side is harder and considerably more useful than twice the reps at speed.
Variations & progressions
- Easier: slower pace, smaller range.
- Harder: pause at each twist.
- Keep legs lower (closer to the floor) for more challenge.
How it compares
Electromyography studies have repeatedly found the bicycle crunch among the higher-activation exercises for the rectus abdominis and obliques, which is why it persists in programmes despite being unglamorous. Against a plank, it trains the opposite quality — producing movement rather than resisting it — and both belong in a complete programme.
Equipment
None. A mat protects the lower back and tailbone.
Looking for a full routine? Try our beginner bodyweight workout.