EXECUTION
- Lie on your back on the floor with your thighs vertical (perpendicular to the trunk) and with the knees bent. Your hips, shoulders and head should be in full contact with the floor with the arms alongside the body or behind the head for increased difficulty.
- Your eyes should be focussed on the ceiling with your feet and legs unsupported, free to move.
- Inhale slightly more than usual, and hold your breath as you raise your head and shoulders and hips simultaneously.
- Concentrate on bringing the hips and the shoulders up as high as possible in a curling motion. Bring your knees toward the chest and your head and shoulders toward the hips.
- As you execute the double crunch, shift your eye focus so that in the up position, you are looking toward your feet.
- Exhale and return to the beginning position under control. Relax momentarily and then repeat.
- The range of motion will not be great because of the limited rotation possible in the lumbar and thoracic spine when controlled by abdominal muscle contractions.
WORKOUT TIPS
Be sure to hold your breath as you rotate the pelvis and head and shoulders upward and toward each other. The breath-holding gives you greater force and creates greater intra-abdominal pressure to help protect your spine. Exhaling on the up phase limits your range of motion and makes you weaker and more susceptible to injury.
Keep the knees bent when doing the double crunch. If you maintain straight legs you may develop a swinging motion which makes the exercise easier by not taxing the muscles as much. When the knees are bent you must rely on the abdominals to rotate the pelvis upward.
To prevent permanent rounding of the shoulders, as occurs in only doing the crunch, it is important that you fully lower the body on each repetition. The hips, head and shoulders should make full contact with the floor. In essence, you want the spine to return to the neutral position.
Doing the exercise with the arms alongside the body can assist you in going through a full range of motion. As you curl the head and shoulders upward, let the arms extend towards the legs so that they give an assist to the movement. If you keep your hands behind your head, the difficulty increases greatly and it may cut down on your range of motion.
Do not keep looking up at the ceiling as you go through the full range of motion. You want a curling action, so that your head and shoulders rotate toward the feet as the hips rotate upward toward the head. Looking directly upward will interfere with the abdominal muscle contraction and may even cause injury.
Do not pull your head forward. Concentrate on raising the shoulders up in the curling action. The head should follow the shoulder action and not vice-versa. Jerking the head up can be injurious to the cervical spine.
Do not do any twisting as you raise the pelvis or head and shoulders. Twisting the shoulders or hips when the spine is flexed creates excessive shearing and compression forces that can be injurious to the discs.
Raising the hips is more difficult than raising the head and shoulders. Thus you may wish to concentrate more on raising the hips as you begin the exercise rather than raising the head and shoulders. Once the head and shoulders are up, it becomes extremely difficult to get the hips up. Thus many people find it easier to get the hips started first. Once the hips are in motion, then immediately bring the head and shoulders up and forward.
If you have difficulty doing the double crunch, try a variant of this exercise in which the movements are done in sequence, rather than simultaneously. Begin in the same starting position, and then do a reverse crunch raising the hips off the floor with the knees toward the chest. Hold the hips off the floor and then execute a crunch raising the head and shoulders as high as possible.
It is important that the legs be free to move. In doing a regular crunch, you can use the legs to elicit a stronger contraction or to make the exercise more difficult. However, in the double crunch, when there is movement from both ends of the abdominal muscle, it is important that the legs be free of support.
MAJOR MUSCLES INVOLVED
The rectus abdominis, internal oblique and external oblique are maximally involved in this exercise. The rectus abdominis is a long slender muscle running vertically down the abdomen from the lower rib cage to the pelvic girdle. The upper portion of the rectus abdominis has tendonous strips that run horizontally to provide the divisions usually seen in a “ripped” mid-section. The internal and external oblique muscles cover the front and sides of the abdomen from the sides of the rectus abdominis to the latissimus dorsi. The fibers of the external oblique run at an angle downward on both sides of the body to form the letter “V”. Directly underneath the fibers of the internal obliques form an inverted “V” at the upper end. The internal oblique fibers are more horizontal in the lower abdomen.
MUSCLE/JOINT ACTIONS
In this exercise you execute spinal flexion with two axes in the spine. Raising the pelvis has the axis in the lumbar spine, while raising the head and shoulders in a crunch action uses an axis in the thoracic spine but may also be in the lumbar area. Both of these actions occur simultaneously to round the back as you rotate the pelvis and shoulders up toward each other.
SPORTS USES
The main value of the double crunch is in bodybuilding and in general fitness for producing muscle strength and getting well developed abdominals. The greatest value of this exercise in sports is in the pelvic movement to develop the lower portion of the abdominals. The pelvic rotation is very important in running, jumping and kicking when bringing the leg forward and whenever raising the legs as for example in execution of various stunts on the gymnastics apparatus. The crunch of the upper body with the axis in the thoracic spine is not used in sports. In almost all sports skills, the axis for spinal flexion is in the waist or lumbar spine. Then you have a direct transfer to the sports. For overall strengthening of the abdominals, the exact axis is not that important. Because the lower portion of the abdominals is involved in raising the hips, you have an action in the waist. As a result the abdominals assist in sports such as gymnastics, diving, wrestling and the martial arts where flexing of the spine is extremely important. In addition it has value in execution of various sports skills such as baseball pitching, soccer throw-ins, javelin throwing, shot-put, and boxing.