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how to do crunches

Short and targeted, crunches curl only your upper back off the floor, which keeps the work in your abs and leaves the hip flexors mostly out of it. That smaller range is what separates them from sit-ups, and it's why they tend to be kinder to a sensitive lower back. With your arms reaching forward, they're an easy entry point into core training. The limitation: once you can do 20 slow reps with a pause at the top, more reps add little, so move to reverse crunches, bicycle crunches or longer levers.

▶ watch crunches on the dedicated video page

primary musclesabs
also worksobliques
levelbeginner
equipmentnone — bodyweight
typerep-based

how it’s done, step by step

  1. Lie on your back with knees slightly bent, feet placed on the floor and arms raised to the shoulder height.
  2. Squeeze your abdominals and lift your upper back off the floor, reaching forward with your arms
  3. Hold for few seconds and slowly return to the starting position.

how much: Start with 3 sets of 8–10 reps, and before adding more, stretch the top hold to three seconds.

form tips from the wandelbar coaches

  • Exhale fully as you lift, drawing your lower ribs toward your hips like closing an accordion.
  • Keep a fist-sized gap between chin and chest so your neck stays long throughout.
  • Reach your fingertips toward your knees, lifting only until your shoulder blades clear the floor.

common mistakes

  • Jerking up with swinging arms — pause for one second at the top so your abs, not momentum, hold you there.
  • Lifting too high, into a sit-up — stop once your shoulder blades leave the floor and hold there.
  • Lower back arching off the mat on the way down — press it gently into the floor as you lower slowly.

make it easier or harder

easier
Slide your palms up your thighs toward your knees as you curl, which shortens the range and gives your arms a clear target.
harder
Double crunches, lifting your knees toward your chest as your shoulders curl up, work both ends of your abs at once.
crunches at the top: shoulder blades lifted, arms reaching toward the knees
crunches — correct starting position

similar bodyweight exercises

sit-ups halfway up: knees bent, feet flat, hands lightly behind the head sit-ups plank on forearms: elbows under shoulders, body straight from head to heels plank mountain climbers in high plank: one knee driven toward the chest, hips level mountain climbers bicycle crunches mid-twist: elbow reaching toward the opposite knee, other leg extended bicycle crunches leg raises top position: lying flat, straight legs pointing up at the ceiling leg raises hollow hold: shoulders and straight legs lifted, lower back pressed flat hollow hold

never wonder what to train next

crunches is one of 1,300+ exercises in the wandelbar app — where you don’t pick exercises at all. Answer a few questions, get a personal 90-day bodyweight plan, and it reshapes itself after every session. free for 7 days.

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