Major Muscles and Actions Involved
In this exercise the lower portion of the abdominal muscles, especially the rectus abdominis, shorten to perform spinal flexion. In this action the lower pelvic girdle rotates up and toward the upper trunk. This involves an opposite rotation of the pelvis in comparison to what occurs in the sit-up or crunch.
Muscles in Action
The reverse sit-up is an important exercise for all sports that require abdominal strength to rotate the pelvis posteriorly to produce a maximum ROM to rotate the legs up high. Thus, gymnasts perform this exercise to develop the muscles needed to raise their legs to a 90-degree angle or higher in many of the stunts executed on the apparatus and in free exercise. Likewise, it is an important exercise for dancers, especially for developing the muscles needed to raise the legs in ballet leaps and in modern dance.
Important Facts to Know
- If you want to also involve the upper abdominal muscles, continue bringing your pelvis and bent legs up and over until your knees are above your head. Doing this produces a maximal stretch of the spine. However, this is an advanced movement and is not a key element of the reverse sit-up. The main factor in successful development is to have the pelvic girdle fully rotated off the floor, at which point the lower abdominal muscle fibers are maximally contracted.
- In the beginning movement of this exercise, you may find it helpful to press hard with your hands against the floor to assist you in getting your pelvic girdle rotated up and over. More importantly, if you want maximum muscle involvement, you must use your lower abdominal muscles to start the pelvic girdle rotation. Once you can do the exercise more easily, you should place your arms over your head. In this position you will have to rely solely on pulling with your abdominal muscles.