Basic Abdominal Crunch


Basic Abdominal Crunch Exercise Guide

The basic abdominal crunch is one of the simplest and most popular of all exercises. It helps you to develop a strong core and improves your posture, but you must ensure you have good form. Crunches (also known as curl-ups) are a very effective ab exercise with several variations.

Difference Between Crunches and Sit-Ups

Sit-ups and crunches are sometimes used interchangeably, but there are some noticeable differences between these two exercises. Sit-ups are generally a larger movement compared to crunches because you are raising your torso until you reach a semi-seated position. When you perform crunches, you are raising only your head and shoulders to move your ribcage toward your pelvis, without lifting your lower back.

The crunch exercises involves only the abdominal muscles, while the full sit-up involves both the abdominals and other stabilizing muscles – in the chest, neck and low-back as well as hip flexors and lower-leg muscles (if you hook your feet). Sit-up is therefore less specific than the crunch.

Basic Abdominal Crunch Technique

Basic Abdominal Crunch Technique

Basic Abdominal Crunch Technique

STARTING (INITIAL) POSITION: Lie face-up on the floor with your hands behind your head (fingers interlocking).  As alternatives, you can cross your arms across your chest or you can keep them at your sides. Keep your feet on the floor close to your buttocks, with your knees bent and slightly open. You can also rest the backs of your calves and ankles on the bench, with your legs bent at a 90-degree angle.

EXERCISE EXECUTION (MOVEMENT): Curl your trunk up to the point at which the middle of your back comes
off the floor, but keep your lower back touching the floor. In other words, lift your shoulders by contracting your abdomen in a short, controlled movement while rounding your back slightly. Just roll your shoulders toward your knees a few inches. Squeeze at the top position for two counts, then slowly return to the starting position.

Abdominal Crunch Video Demonstration

This video will show you exactly how to perform this exercise safely and effectively.

Basic Abdominal Crunch – Tips & Common Mistakes

  • If you place your hands behind your head, do not pull on your neck when you curl up. The extra strain may damage the neck vertebrae.
  • Raise your head and shoulders toward your knees, keeping your lower back on the floor. This is a very short movement. There is no motion at the hips. Just try to shorten the space between the pelvis and the chest.
  • Do each rep slowly and deliberately. Jerky movements will bypass the abdominal muscles in favor of the much stronger hip flexors.
  • Major mistakes: lifting your entire torso with the help of the hip flexors, working out too fast using momentum and bouncing, overflexing the head and neck, pushing your head up with your hands, and extending the hips and legs.

Muscles Engaged

The entire rectus abdominis works in this exercise, although it is most demanding for the upper sections.

Main muscles: rectus abdominis
Secondary muscles: external and internal obliques, transverse abdominal, (pyramidal)
Antagonists: spinal erectors

Exercise Variations

  • Exercise ball crunch
Exercise Ball Crunch

Exercise Ball Crunch

  • Vertical leg crunch
Vertical Leg Crunch

Vertical Leg Crunch

  • Crunches with legs on a bench
Legs Supported Crunch

Legs Supported Crunch


While effective and generally safe, crunches do have drawbacks.  One is that many do crunches by the hundreds—or even by the thousands—on a regular basis without switching to other exercises. Overusing crunch exercises can reduce thoracic extension. This means that over-crunching  can literally pull your head forward, leaving your spine in a slightly flexed (hunch-backed) position, which could ultimately lead to poor posture and lower back pain. So be careful.

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