Into the Fold
Degrees of Freedom
So before doing sitting forward bends like Paschimottanasana, you should have at least 90 degrees in Supta Padangusthasana. If you don't, you risk hurting your back. Instead of rushing into ill-advised forward bends, take time to improve your hamstring flexibility by consistently working on Supta Padangusthasana with a strap, and on Utthita Hasta Padangusthasana (Extended Hand-to-Big-Toe Pose), standing tall with your foot on a chair seat. Both of these poses will stretch your hamstrings while taking your lower back out of the equation.
If you've already been working on your hamstring flexibility, and you can bring your leg to 90 degrees in Supta Padangusthasana, that means your hamstrings are flexible enough to allow your pelvis to sit upright in Dandasana but not yet flexi-ble enough to allow it to rotate forward over your thighs. So if you go too far, the forward movement will come from your low back, causing strain or injury. In other words, to fold forward safely without bending your knees, you'll need to have enough flexibility that your leg can easily come past 90 degrees toward your torso when you're in Supta Padangusthasana.
In the meantime, the solution is to sit up with a folded blanket or firm cushion under your sitting bones to help tip your pelvis forward. You can also defuse the urge to pull forward by sitting with your back against a wall or by placing a folding or kitchen chair directly in front of you, with your legs placed to the inside of the chair legs. Rest your head on the chair seat and focus on relaxing into the stretch rather than forcing your body to go further than it's ready to.!--page-->