Reverse crunches, also known as reverse ab crunches, are an abdominal exercise that targets the lower abs. These exercises involve an athlete lying on his or her back with the legs in the air, then using the strength of the lower abs to lift the legs higher into the air while also lifting the lower back slightly off the ground. There are a number of variations that help to account for the abdominal strength of different athletes.
To perform reverse crunches properly requires correct form and control. At the beginning of the exercise, the athlete should be lying on the floor and the back should be straight. The athlete can begin with the hands either lying on the floor or behind the head. In the most common variation, the athlete then raises the legs into the air until they are at a 90 degree angle to the floor. The athlete should either cross the feet or keep them pressed tightly together.
From this position, the athlete contracts the abdominal muscles so that the legs raise higher into the air. The lower back will raise off of the floor very slightly, no more than 1 to 2 inches (2.5 to 5 centimeters). Then, the athlete lowers the legs back to the starting position and repeats the motion for the desired number of repetitions.
Proper form is vital to effective reverse crunches. It is crucial that the back remains as straight as possible during the exercise, especially the upper back. Also, while performing reverse crunches, it is important that the legs move as a result of the contraction of the lower abdominal muscles, not as a result of momentum from the legs or from rocking back and forth on the spine. If an athlete chooses to place the hands behind the head, he or she must be careful not to pull on the head during the exercise, because this can put harmful strain on the neck.
There are a number of variations for reverse crunches. One variation is to bend the knees and bring them closer to the chest at the start of the exercise. Then, during the reverse crunch, the athlete lifts his or her head toward the knees at the same time that the lower abs bring the knees closer to the body. This version of reverse crunches will put a slight curve in the upper back, but the athlete should keep this curve to a minimum. During this variation, it is imperative that the athlete does not rock, because this can be harmful to the spine and reduces the benefits of the exercise.
Another variation of reverse crunches requires the athlete to begin with his or her legs straight and just inches off the floor. Then, the athlete contracts the lower abs while bending the knees in order to bring the knees all the way to the body before returning to the initial position. It is important that athletes performing this variation focus on a steady and controlled motion. Moving too fast will cause the momentum of the legs to reduce the work that the abs are doing and thus decrease the benefits of the exercise. This variation requires more strength in the lower abs than other variations of reverse crunches, so it is not appropriate for inexperienced athletes.