Lie face up on the bed, knee flexion at 90 degrees, feet flat on the floor. Do not put your feet on the ground is fixed (for example by companions with his hands on his ankle), thigh and hip flexor might join the work, thus reducing the workload of the abdominal muscles. Furthermore, straight leg crunches will increase the burden of the back, easy damage to the back. Decided according to ourselves an abdominal muscle strength hands placed position, because the more your hands near the head, sit-ups, it will find it difficult. Beginners can put his hands on the sides, when adapted to or physical improvements, will be able to handle cross affixed to his chest. Finally, they can also try hands crossed behind his head, but each hand should be placed on the shoulders of the other side of the body. Do not put the fingers of both hands crossed behind your head, so as not to forcibly pulled neck muscles, and this also reduces the workload of the abdominal muscles
