Crunches are perhaps the most popular exercise for developing the abdominal muscles. It is an effective exercise for increasing mass and defining the upper portion of the abdominals, but it can produce some negative results as for example a hunchback condition. Also, crunches do not eliminate the hip flexor muscles, but work together with the abdominals at all times. However, the crunch can still play an important role in the bodybuilder’s training.
EXECUTION
- Assume a back lying position with the arms along side the body and the knees bent. Feet should be flat on the floor and your eyes should be focused on the ceiling.
- Cross your hands on the chest or behind the head for greater difficulty.
- Inhale slightly more than usual and hold your breath as you raise your head and shoulders as high as possible. The arms should rise up according to the amount of head and shoulder lift.
- As you rise up eye focus changes so that when you are in the up position you are looking toward the feet. In essence your eye focus changes as your head and shoulders rise up.
- Hold the up position for 1-2 seconds.
- Exhale and return to the initial position with the head on the floor.
- Relax and pause momentarily and then repeat.
WORK OUT TIPS
- Be sure to hold your breath as you raise the head and shoulders. The breath holding gives you greater force and creates greater intra-abdominal pressure to help protect the spine. Exhaling on the up-phase limits your range of motion, and makes you weaker and more susceptible to injury.
- Relax in between each repetition. If you keep the abdominals under constant contraction the muscles will maintain residual tension and not relax as they should.
- Do not work through a shortened range of motion. Fully lower the body so that the head and shoulders are in contact with the floor. This is needed to return the abdominals to the normal position which helps to ensure good posture. Working through a limited range of motion creates excessive thoracic spinal curvature which leads to a hunchback condition.
- Continually doing the crunch can be a detriment to good posture. To counteract the negative effects it is important that you also do exercises such as back raises to maintain and strengthen the normal curvature of the spine.
- Do not do the crunch with a twist. When the spine is flexed and you also rotate (twist) the shoulders, it creates excessive shearing and compression forces that can damage the discs and vertebrae.
- If you experience any back pain when doing this exercise you should have your lower back checked by a competent professional. It should not hurt when executing the crunch or even the sit-up.
- If you have difficulty maintaining the head and shoulder position, placing the fingers along side the head or slightly behind the head to support the head may be beneficial. However, in many cases strengthening the hip flexor muscles are needed to properly support the head so that the muscles are strong enough to maintain the head in good position as you do the exercise.
- Do not look up to the ceiling as you execute the exercise. The head and eye focus should be toward the feet as you rise up. In essence, the head and shoulders circumscribe an arc of a circle so that in the up position you should be looking at the feet. In the down position you would be looking up at the ceiling. If you constantly look at the ceiling as you execute the crunch, hyper extension of the cervical spine will take place which will limit your range of motion and bring in contraction of the lower back muscles.
MAJOR MUSCLES INVOLVED
Only the upper portion of the abdominal muscles is involved in the crunch. The lower portion undergoes contraction or tension to maintain stability in the lower hip area to allow proper upper body movement. The muscles involved include the rectus abdominis, external oblique and internal oblique. The rectus is a long slender muscle running vertically down in the abdomen. It has a right and a left half and is separated by tendonous strips to provide the divisions usually seen when one has ripped abdominals.
The external oblique muscle covers the sides and front of the abdomen from the rectus abdominis to the lattisimus dorsi muscles. The fibers run diagonally upward and sideward from low to high on both sides of the abdomen and form the letter “V”. The internal oblique is located directly underneath the external oblique. Its fibers run at nearly right angles to the external oblique forming an inverted “V”.
MUSCLE ACTION
In the crunch the upper abdominal muscles flex the thoracic spine. In this action the head and shoulders move up and toward the lower body. The main muscle is the rectus abdominis since the obliques essentially cancel out each other’s effects to provide pure flexion.
SPORTS USES
The crunch is very beneficial in bodybuilding and in general fitness. Since the movement is through a short range of motion it is effective for producing muscle definition and well developed upper abdominals. However, because the axis of rotation is in the thoracic spine, the abdominal development is not most effective for most sports. The abdominals play a very important role in flexing the spine, an action which is important for gymnasts, divers, trampolinists, wrestlers, karate fighters, hand balancers, and in execution of various stunts and skills. In addition, the crunch is valuable for the development of the upper abdominals which play a role in body building, and throwing sports such as baseball pitching, soccer throw-ins, javelin throwing, shot put and others. For more information on this and other exercises, see KINESIOLOGY OF EXERCISE by Dr. Michael Yessis.