Often in this pose, there is too much lumbar extension and not enough hi extension. The hamstrings should be the main extensors here, but if they are weak, the gluteus maximus can kick in. A problem with this, however, is that it brings in external rotation, which is harder on the lower back. The gluteus maximus can also overdo the lumbar extension.

If the hamstrings are too weak to do purvottanasana, then tabletop (chatus pada pitham, discussed later in this chapter) is great preparation.

The latissimus dorsi are not so helpful in this pose, because they can fix the scapulae on the rib cage and inhibit extension in the thoracic spine.