The opposite of a sit-up, a reverse crunch is an exercise used to train the abdominal muscles. Considered a safer alternative to sit-ups, the reverse crunch works the entire rectus abdominis, the long muscle that makes up both the upper and lower abdomen. Without the requirement of added weights or equipment, reverse crunches are an accessible workout for most people.
People choose the reverse crunch as an alternative to sit-ups for a variety of reasons. They may have bad posture, which can be exacerbated by doing sit-ups. They may also experience back pain during sit-ups, or suffer from a shortened hip flexor, which can be aggravated by doing sit-ups.
Reverse crunches can help improve these problems. Not only can the movement aid in correcting posture; it can also strengthen the oblique muscles and correct lordosis, or an inward curvature of the vertebrae column, by tilting the pelvis correctly. The reverse crunch can help prevent kyphosis, or upper back rounding, by keeping the ribcage in line during the workout. Reverse crunches are a popular way to achieve the six-pack abs that many people strive to attain.
To do a reverse crunch, lie on the floor. Hands should be placed on the floor or behind the head. Bring the knees towards the chest, bending them to a 90 degree angle. Feet should be crossed or together. The abdominal muscles should be contracted to allow the hips to curl off the ground in a very small movement as the legs lift toward the ceiling.
After lowering the legs, the exercise can be repeated. Twelve to sixteen repetitions are recommended. Avoid swinging the legs to create momentum; instead, use the abdominal muscles to lift the hips for the best workout. During each repetition, the lower back should push against the floor; hands should not be able to fit behind the back during the movement.
Feet should remain down during the movement, as should the head; they do need to come up as the abdominal muscles are worked. Knees should be flexed, moving upward towards the head; the head should not be moved toward the knees. The lower back should not be arched, which can cause pain; rather, the pelvis should be tilted during each repetition as the lower back is pushed against the floor.
Though not necessary, added equipment can add intensity to the workout. A dumbbell or medicine ball can be utilized as a counter weight during the movement. As the abdominal muscles get stronger, the counterweight can be lowered to create more of a challenge.