Muscle group:   The abdominal muscles

Trained muscle:   All parts of the abdominal muscles

Focused muscle:   Rectus abdominis (straight abdominal muscle)

Fitness level:   Beginner, advanced, experienced

Type of training:   Own body weight exercises


The abdominal crunch is probably the most practiced belly exercise. There is a large range of variations we can choose from that can be performed by all fitness levels.

Abdominal crunch

The abdominal crunch is more gentle than sit-ups because the hips remain in a better position that keeps the spine straight. We start in supine position. The legs are bent upward at approximately 90° (knee joint) and should remain in this position to prevent a hollow back. The feet press against the floor and slightly pull towards the body to get a pretension. The hands hold on the sides of the head with the finger tips behind the ears. This will bend the arms automatically. Never pull on your head with your hands. This could cause damages or injuries to the cervical spine. The entire spine should be kept as straight as possible during the exercise. Press your lower back onto the floor. Hunching must be avoided. Between chin and chest we should be able to fit our fist at any time during the exercise.

Abdominal crunch correct execution

Abdominal crunch correct execution

To check whether you work out with a hollow back or not try to place one hand flatly below your lower back. If you can fit your hand below your back is hollow. Tense your abdominal muscles and press your lower back actively onto the floor. First, do it with your hand still there to feel the pressure of your back. With the time you will develop a feeling for the right position what allows you to skip this test.

In this position we now lift the upper back smoothly from the ground flexing our abdominal muscles. In clean execution of the abdominal crunch we try to lift our upper body as high as possible. From that position we smoothly reverse this motion until our back slightly touches the ground again and we can start over. It is important to keep your abdominal muscles tensed at any time during one set of repetitions.

A right breathing is important as well. Breathe out while you are lifting the upper body from the ground and breathe in in the reverse motion. Avoid press breathing (exhalation against closed airways).

Abdominal crunch Variations

Working out abdominal crunches we have many different options we can choose from to shift the intensity. The further we stretch our arms toward the front the easier the exercise becomes. The further we bring our arms to the back the more intense it gets. Advanced and experienced sportsmen and -women could also lift their bent legs or even stretch them upward or toward the front, what makes the exercise even more intense. It is also possible to use extra weights to increase the intensity. Keep them held tight with both hands on your chest.

Please note that performing abdominal crunches the rectus femoris (see the leg muscles) is tensed as well. The more we lift and stretch our legs during this exercise the more the rectus femoris will be stressed accordingly. Here, we have the high risk of developing a hollow back what could cause damages and injuries. Please always make sure that your lower back remains flat on the ground. Moving the hands under the buttocks supports that and erects the pelvis.


Further familiar exercises of the abdominal crunch are the reverse crunch, the bicycle crunch, and variations of the ab crunch.

Antagonist: Lower back muscles

Stretching: Abdominal stretches

Straight abdominal crunch

Straight abdominal crunch with different arm positions

abdominal crunch

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