Executing the posture in this way disengages both the gluteus maximus (butt) muscles and the abdominal muscles. These two huge muscle groups generally suffer from our western lifestyles, with so much sitting in chairs. It makes sense that they are weak, and the posture has altered to compensate for our weakness.
HOW TO CHANGE
To execute the posture properly, as has been done from Bose to Choudhury, the glutes and abs must engage to tilt the pelvis backward. This flattens the spine. The weight shifts back significantly, which means that the ankles must bend to push the knees forward. Notice the position of the knees of Bose, Mukerji and Choudhury. They are all significantly forward of the ankles.
Learning to practice Chair Posture this way can be challenging, especially when we've done it incorrectly for so long. Start very slowly. Bend the knees only slightly, and push them forward. Instead of focusing on your hips going back, bend your knees and push them forward. Whenever you feel your upper body leaning forward, straighten your legs a little bit, stand up, and again push your knees forward. Avoid letting the spine arch. Keep the back flat. You will notice that your abdominal muscles need to be quite tight.
Practicing this way will integrate the muscles of your pelvis and spine, strengthen your ankles and improve your balance significantly.
This journal honors my ongoing experience with the practice, study and teaching of yoga.
1) Sridaiva Yoga: Good Intention But Imbalanced
2) Understanding Chair Posture
2) Why I Don't Use Sanskrit or Say Namaste
3) The Meaningless Drudgery of Physical Yoga
5) Beyond Bikram: Why This Is a Great Time For Ghosh Yoga