Crunch exercise: how to do it, benefits, and common mistakes

The abdominal crunch, often referred to in Portuguese as abdominal supra, is one of the most popular core exercises worldwide.

Simple yet effective, the crunch specifically targets the upper part of the rectus abdominis muscle. However, despite being widely practiced, it’s often performed incorrectly, which can limit results or even cause neck and back pain.

In this article, you’ll learn what the crunch is, how to perform it properly, its variations, benefits, common mistakes, and how to add it to your workout routine for maximum results.

What is the crunch exercise?

The crunch is a core exercise designed to strengthen the rectus abdominis, with greater emphasis on the upper portion. It involves lifting the shoulders and upper back off the ground while keeping the lower back in contact with the floor.

Because of its simplicity, the crunch is often recommended for beginners, but it can also be adapted for more advanced athletes with added resistance and variations.

How to perform the crunch correctly

1. Lie on your back on a mat.
2. Bend your knees and place your feet flat on the ground.
3. Cross your arms over your chest or place your hands lightly behind your head (avoid pulling the neck).
4. Contract your abs and lift your shoulders a few inches off the floor, directing your chest toward your knees.
5. Lower yourself slowly back down, keeping tension in the abs.

Tips:

• Keep your chin slightly tucked, as if holding an apple under it.
• Breathe out while lifting, breathe in while lowering.
• Focus on short, controlled movements — avoid pulling with your arms.

Benefits of the crunch exercise

• Strengthens the rectus abdominis: especially the upper section.
• Improves posture: a stronger core helps stabilize the spine.
• Supports other exercises: a solid core enhances performance in squats, deadlifts, and sports movements.
• Prevents lower back pain: when done correctly, crunches help protect the lumbar region.
• Accessible exercise: requires no equipment and can be done anywhere.

Crunch variations

1. Weighted crunch

Hold a plate or dumbbell against your chest to increase resistance.

2. Incline bench crunch

Perform the exercise on a decline bench to increase difficulty.

3. Isometric crunch

Hold the top position for several seconds, maximizing muscle tension.

4. Stability ball crunch

Perform the crunch on a Swiss ball to activate stabilizer muscles.

Common mistakes when doing crunches

• Pulling on the neck: this can cause cervical strain.
• Excessive range of motion: lifting too high engages hip flexors instead of abs.
• Using momentum: the movement should come from abdominal contraction, not swinging.
• Incorrect breathing: holding your breath reduces efficiency.
• Overemphasis on quantity: quality and control matter more than doing hundreds of reps.

How many crunches should you do?

The number of repetitions depends on your fitness level:

• Beginners: 2–3 sets of 12–15 reps.
• Intermediate: 3–4 sets of 15–20 reps.
• Advanced: 4+ sets of 20 reps, with added resistance or advanced variations.

Crunches can be included in ab-focused workouts 2–3 times per week.

Do crunches burn belly fat?

No abdominal exercise, including crunches, directly burns belly fat. Fat loss occurs through overall calorie deficit — combining proper diet, cardio, and strength training. Crunches help define and strengthen abs, making them more visible when body fat levels are reduced.

Crunch vs. sit-up

• Crunch: shorter movement, focuses on abs only.
• Sit-up: full trunk lift, engages hip flexors along with abs.
• Best option: both can be useful, but crunches are safer for beginners and those with back issues.

How to include crunches in your workout

• Combine crunches with planks and oblique exercises for complete core training.
• Use them at the end of strength training sessions as a finisher.
• Alternate between variations weekly to avoid adaptation.

A simple exercise with great results

The crunch exercise is a straightforward but highly effective way to strengthen and define your upper abs. By performing it with proper technique and avoiding common mistakes, you’ll build a stronger core, improve posture, and enhance performance in other activities.

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