- Assume a side-lying position on a Roman chair, oblique bench or Yessis Back Machine. Be sure that your hips are directly on the seat when you secure the feet between the rollers or under the rollers depending upon the machine. Your waist should be on the far edge of the support seat when your legs are secured. Your trunk should be unsupported and held in place in a horizontal position by your mid-section muscles.
- When you are ready, inhale and hold your breath as you lower the trunk under control as far as possible so that the muscles involved are placed on stretch.
- Exhale as you approach the bottom position and then quickly inhale and hold your breath as you raise your trunk up as high as possible in the side plane. Your trunk should go through approximately a 60-90º range of motion.
- Cross your hands on your chest or for a greater resistance and difficulty, hold your arms fully extended above your head.
- After you reach the uppermost position, exhale and return to the bottom most position at a moderate rate of speed with your body under complete control.
- When you finish doing the exercise on one side, dismount and reposition yourself on the opposite side to work the same muscles on the opposite side of the body.
The oblique crunch is more difficult than the typical crunch for two very important reasons:
- You go through a greater range of motion, and
- the muscles involved in this movement are often weak for this action because most people exercise the muscles in an anterior/posterior plane front to back (not in the lateral plane).
For maximum benefit, be sure to raise the trunk as high as possible to get maximum shortening of the muscles in this action. Be sure not to twist the shoulders are you rise up or lower the body. The upper torso must remain in a side position at all times during execution. Twisting as you raise or lower the trunk can cause injury to the spine. The oblique crunch on a bench is much more effective than doing the exercise on the floor or in a standing position. It is the only exercise in which your trunk is pulled from the opposite side (below the horizontal) through the same side as the muscles involved. Additional resistance is not needed when you first begin this exercise. The weight of your upper body is usually quite sufficient, however, if you can execute the exercise easily, you should then hold light weights in the hands when the arms are crossed on the chest.
MAJOR MUSCLES INVOLVED
The abdominals, erector spinae, and quadrattius labarum are the major muscles involved in oblique crunches. The abdominals include the erectus abdominus, external obliques and internal obliques. The erectus abdominus is a long slender muscle running vertically across the abdominal wall from the lower ribs to the pubic bone. The external oblique covers the sides and front of the abdomen from the erectus abdominus to the latissimus dorsi muscles. The fibers run diagonally upward and sideward from the lower attachment on both sides of the abdominal and form the letter “V”. The internal oblique is located directly under the external oblique. Its fibers run are nearly right angles to the external oblique forming an inverted “V”. The lower back muscles composed of the erector spinae muscle group, which consists of four separate but intertwined muscles. These long and slender muscles cover a large area running from the neck to the sacrum directly on a posterior spine and on both sides of the spine. Also involved is a deep spinal muscle group that plays an important role in holding the vertebrae and discs in place and in moving the spine. They play a minor role in this exercise. The quadrattius labarum is a flat sheet of muscle fibers on each side of the spine beneath the erector spinae. It runs from the top of the ileum and the lower lumbar vertebrae to the lower ribs and upper lumbar vertebrae. The trunk must remain in a side-facing position at all times.
MUSCLE AND JOINT ACTIONS
The major muscles involved in the oblique crunch execute lateral flexion of the spine. In this action, the trunk is pulled over from one side to the other in the lateral plane. When rising up, the upper portion of the erectus abdominus, erector spinae, external and internal oblique, and quadrattius labarum are involved in pulling the trunk upward. When you turn over on the opposite side, you then work the same muscles on the opposite side of the body.
SPORTS USES
Bodybuilders and athletes need this exercise for total development of the abdominal and lower back muscularature. In addition, this is the only exercise that strengthens the quadrattius labarum muscle, which plays a very important role in posture and in lower back safety. Because of its role in helping to stabilize the mid-section, it is very valuable for all athletes who do heavy lifting overhead or receive heavy blows to the body from the side, as in football. This exercise is needed by all athletes who throw overhead for maximum distance or force such as baseball pitchers, outfielders, football quarterbacks, and javelin throwers. It is also important for hitting overhead as in the tennis serve and smash and when you reach up as high as possible in basketball rebounding, volleyball spike, etc. The oblique crunch is also a very valuable in karate and boxing when punching and kicking. It is also used in many wrestling moves. In gymnastics, it is important for gymnasts working on the horse, horizontal and uneven bars, and in free exercise when executing various stunts in a side plane. It is also valuable for acrobats and many stunts in hand balances and dance and for divers and trampolinists.