Ball Crunch (On Stability Ball)
The (Ab) Crunch is one of the best-known exercises for the abdominal muscles. The rectus abdominis (the basis of the 'six-pack') draws the sternum toward the pelvis by rounding the back.
The obliques on the sides stabilize the core by resisting lateral tilting and rotation. The transversus abdominis (beneath the obliques) draws the abdominal wall inward and thereby acts as a natural weightlifting belt to stabilize the core. When performed on a stability ball, these muscles may have to work harder. The muscles in the legs and glutes will also have to work harder to stabilize the body.
Ball Crunch execution
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1
Lie with your back on the stability ball. Make sure the ball is positioned in the natural curve of your back.
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2
Place your feet flat on the floor.
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3
Cross your forearms over your chest.
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4
Straighten your back and then round it by bringing your chest toward your pelvis.
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5
Hold the tension for 1 to 2 seconds.
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6
Slowly bring your chest back and down.
Ball Crunch
Active muscles:
- Rectus abdominis (straight abdominal muscle)
- External oblique (outer oblique abdominal muscle)
- Internal oblique (inner oblique abdominal muscle)
- Transversus abdominis (transverse abdominal muscle, or 'corset muscle')
Ball Crunch technique
In addition to the stabilizing muscles on the sides having to work harder because of the ball, the involvement of muscles in the legs also changes.
Leg muscles
During training, one of the thigh muscles is often also recruited unconsciously. The rectus femoris is one of the quadriceps muscles. It is the only quadriceps muscle that crosses not only the knee joint but also the hip joint.
The rectus femoris brings the thigh toward the pelvis and the lower part of the spine, and vice versa. It is a so-called hip flexor and therefore brings the thigh forward from the hip joint. This also happens when the torso is brought too far toward the thigh during an Ab Crunch, making it start to resemble a Sit-Up.
On a stability ball, you are less inclined to tilt from the hips, so the rectus femoris will also be recruited less during the active movement.
However, the muscles in the legs have to work harder to stabilize than during a normal crunch. The hamstrings and calves, for example, ensure that you do not roll away from the ball.
Greater range of motion
The range of motion also changes on the stability ball. The back does not lie flat on the floor but is tilted backward by the curve of the ball (hyperextension). You therefore move from an arched position to a straight position and then into a rounded back. You skip that first step during normal crunches.
Bosu ball as an alternative
The Bosu ball can be used as an alternative. It is a half ball with a flat surface on the underside. This allows you to retain the greater range of motion, while the legs and obliques have to work less hard to stabilize.
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