Adho Mukha Svanasana with a chair for your legs

I find that using the chair this way for Adho Mukha Svanasana gives me maximum extension on my back body AND a wonderful Mula Bandha.  I hit my heels strongly out against the chair legs, lift my legs up to get the maximum height in my hips and then my goal is to slowly, without losing any height in my hips, descend my heels and push the chair back.  – Didi Hall, Certified Iyengar Yoga Teacher