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Abdominal trainer

Strong abdominal muscles are desirable for health reasons. The benefits not only enhance appearance, but also prevent and reduce lower back problems. Abdominal exercise also can improve the internal circulation of some organs and the back nervous system. The abdominal area of the human body is comprised of four muscle groups including the rectus abdominis, the external obliques, the internal obliques and the transverse abdominis. Human abdominal muscles are chiefly comprised of the rectus abdominus. The rectus abdominus muscles are a pair of elongated, planar muscles, on either side of the navel, which extend along the entire length at the front of the abdomen from the lower rib cage to the pelvis. The rectus abdominus muscles are interconnected by a band of fibrous connective tissue which creates a greater abdominal region beneath the sternum. There are numerous abdominal exercises that an individual may practice in order to decrease abdominal girth, strengthen the abdominal muscles and maintain abdominal muscle tone. Common modes of abdominal muscle exercise include sit ups, "ab crunches", leg lifts, and kneeling roller assisted thrusts. Sit-ups exercise the full trunk and thus work the thigh flexor muscles as well as the abdominals. When performing sit ups, an exerciser typically lies supine upon a flat surface with hands behind the head. In such position, the exerciser repeatedly flexes and extends from the waist between the supine position and a substantially doubled position wherein the exerciser's forehead approaches thighs or knees. Variations of the sit-up exercise include starting from a fully flexed position and lowering to an intermediate position which is held before returning to the upright position. Another variation, called a "sit-up twist," entails a twisting motion at the end of the upward movement such that one elbow touches the opposite knee. A twisting motion at the end of the curl, such as in a sit-up twist, serves to exercise the external obliques in addition to the rectus abdominis. Ab crunches are similar to sit ups with the exception that the exerciser's legs remain flexed with knees raised and with soles of feet pointing downward. In performing ab crunches, the exerciser's bodily motion focuses upon repeatedly tensing and releasing abdominal muscles for bowing the spine, rather than performing gross flexions and extension of the upper body from the waist. Apparatus for facilitating such ab crunch exercising motion typically comprises a flat board having low ledge or bar for engaging and holding the anterior aspects of the exerciser's feet. The most basic type of leg lift entails a person lying supine to extend and raise both legs upward to approximately 90 degrees and then to lower them to their original position. Variations on the leg lift include bending at the knees, alternating leg lifts, raising the legs to different heights and in different directions, and simulating a bicycle pedaling motion in the air. Leg lift exercises develop the transverse abdominis and lower rectus abdominis muscles as portions of the lower body are raised and lowered while the upper body remains stationary.

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