Crunch ground resistance exercise refines and tones waistline if you work with your body weight. It develops abdominal if you use a ballast increasingly heavy.
The crunch is seeking the rectus abdominals and obliques.
The rectus or “chocolate bar”, is part of the lap with the oblique and transverse. The action of the rectus is the trunk flexion.
Running the exercise
Starting position lying on the floor or on a bench, lower back glued to the ground. The legs can be bent to the chest, resting on a bench or at a 90 degree angle with the feet on the ground. Wrap the torso forward by contracting the abdominals and lower back keeping glued to the ground.
Return to the starting position should be performed smoothly, keeping the contraction and tension in the muscle. The execution speed is slow and steady. You can place a weight on the chest, a washer or cast a dumbbell to add difficulty to the exercise
Inspiration onset of movement when the chest is opened. Blow by executing the movement.
Avoid placing your hands behind your head, because often we are using it to exercise when one blocks; this can cause problems for cervical. The easiest way is to keep your hands on the temples or on the chest.
Do not take off the lower back; the very small amplitude does not take effective exercise.
You have to work unblocked feet, tight and knees apart; this limits the activity of the hip flexors, iliopsoas and rectus, and avoids many back problems.