Abdominal muscles

Strengthening of the abdominal muscles
The abdominal muscles have a great influence on the general health of the body,  particularly on digestion and posture.
If the muscles of the trunk should act as a corset to hold the spine in place, the abdominal muscles should be a corset for abdominal organs. Weakness and flabbiness could lead to their displacement.

In some cases of extremely large stomachs, the digestive organs are literally outside the frame of the skeleton. The balance of the body is thus upset and backache is inevitable. Curvature or other spinal distortions may also result. Post-natal neglect, if allied to obesity, could create the same effect. 

Yoga considers all these possibilities and the training includes many exercises for developing strong abdominal muscles. Among the most important techniques are the cycle of abdominal contractions:
Uddiyana and Nauli but the muscles must be toned up and strengthened before these contractions can be practiced with any success.
If any of the movements given here cause pain in the back they must be discontinued in others tried, until the right ones are found.

Where there is extreme excess weight it must be reduced. This is imperative in every case of backache. 
The exercises have been grouped as light, medium and more strenuous.

Light exercises
Urdhva Prasarita Padasana *

1. Lie down flat on the back. Alternatively raise the right, then left leg to an angle of 45 degrees with the floor. 

2. Lie flat on the back with the arms raised above the head. Stretch the arms and body smoothly.

3. On the back, press the right knee to the stomach with both hands, then slowly lower the leg. Press left knee to stomach and lower. 

4. Press both knees together to stomach and then slowly lower. If this movement is combined with inhalation and retention of breathe it brings blood to the head, producing a powerful ‘flushing’ effect on the brain. It is forbidden in cases of high blood-pressure.

Medium exercises
Urdhva Prasarita Padasana *
1. Lying flat on the back, with arms by the sides. Raise both legs up to an angle of 45 degrees with floor. Lower them down slowly.

2. Lying on the back, describe small circles with the legs, keeping them straight. Raise the legs sepeartaly as you describe the outward and upward curve of the circles, then bring them together as they come down.
3. Lyning flat on the back, bring both knees up to the stomach, then stretch them up at 45 degree angle to floor and slowly lower.

4. Lying flat on the back with arms stretched above the head. Swing the arms down and forward till palms rest on the floor at the sides, sitting up at the same time. Repeat several times, making it a continuous movement.

More strenuous
Ardha Navasana *
1. Lying flat on the back, clasp the hands under the neck and slowly sit up keeping the heels on the floor. 
2. Flat on the back, with the hands under the neck or by the sides. Bring the knees up to the stomach, then stretch the legs out and up to 45 degree angle, at the same time coming into a half sitting position. 
The whole movement is done quickly. 
Navasana *
3. Lying flat on the back with arms stretched above the head. Swing the arms forward and down till the palms rest on the floor and sit up, raising the right leg to 45 degrees angle at the same time. Lie back repeat, with the left leg.
4. Practice the same movement, bringing both legs up at the same time.

Source: Yoga for Backache - Michael Volin & Nancy Phelan

*Asana names have been added by the editor.