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Exercise library · Abs

Crunch

Trunk flexion for the abs with your bodyweight.

How to do it

1 of 3

Lie on your back, feet on the floor

  1. Starting position

    Lie on your back with your knees bent, feet on the floor, and hands resting lightly by your head.

  2. The movement

    Curl your torso and lift your shoulder blades off the floor, then lower slowly back down.

Most common mistake

Don't pull on your neck, keep your hands light and lift with your abs.

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Muscle group
Abs
Equipment
Bodyweight
Where
Home or gym
Logged as
Reps

Muscles worked

The crunch mainly trains the rectus abdominis, the long muscle down the front of your stomach that bends your spine forward. The obliques at the sides help. Because only your shoulder blades leave the floor and your lower back stays down, your hip flexors do little, unlike in sit-ups, where your whole upper body comes up. If you twist to one side as you lift, as in a bicycle crunch, your obliques get more work.

Common mistakes

  • Hooking your feet under something. Anchored feet let your hip flexors help pull you up, so your abs get less to do. Let your feet rest freely on the floor.
  • Holding your breath. Breathe out as you curl up and in as you lower. It makes it easier to tense your abs properly at the top.
  • Expecting crunches to burn belly fat. You cannot choose where on your body you lose fat. Crunches make your abs stronger, but how much fat sits over them depends on the bigger picture of food and activity over time.

Variations and alternatives

  • The bicycle crunch adds a twist and gives your obliques more work.
  • The reverse crunch lifts your pelvis instead of your upper body and is a good swap if your neck tires before your abs.
  • The backpack crunch is the same exercise with a loaded backpack as extra weight, for when you want more load at home.
  • The cable crunch is done kneeling at the cable machine and lets you add weight in small steps at the gym.

Sets and reps

Your abs often handle more reps than larger muscles. Two to four sets of 15 to 25 reps is a good starting point, with a slow lowering and a short pause at the top. What matters is that the last reps are hard, not that you hit a set number. If you can do 30 reps without feeling it, the exercise has become too easy and more reps give you less and less. The guide to sets and reps has more on choosing a range.

Make crunches heavier rather than longer, in line with progressive overload. Hold a weight plate or a dumbbell against your chest, take three seconds on the way down or move to a loaded variation. You can then work in the 10 to 15 range again. Two or three sessions a week are enough for most people.

Swap for

Taken, or missing the equipment? The same movement with something else.

Want it in a programme?

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