On Wednesday William gave us a restorative yoga class... this is when we hold postures for at least 3 minutes. We are allowed to work the posture as much as we like, meaning we can either relax into the posture or be active in the posture on a muscular level. The restorative postures are extremely rejuvenating to the CNS.
Examples of restorative postures would be downward facing dog with the top of your head resting on a support. The significance of pressure on the top of the head is supposed to give calm and quiet to the brain. I know in the world of acupuncture the top of the head is a point given to calm someone down. Other postures we hold for extended periods of time are forward bends, supported back bends and reclining postures. Plus in Iyengar yogaland we always practice timed head and shoulder stands (10 minutes). The emphasis is on turning the gaze inward, turning off outside distraction, rejuvenating the nervous system and calming the brain.
The way I understand yoga asana is that it was exercises for the yogis. These people spent huge amounts of time in seated meditation... this will really goof up your physical body if you don't move it around. All the postures are for something... particularly increasing circulation, the wringing and renewal of blood to internal organs is mentioned several times in Light on Yoga.
My only practice was yoga on Wednesday... the sun was shining when I got home so I had to dig in my garden. I got a new wheelbarrow to try out and hostas to plant, weeds to pull and I didn't want to miss my chance for some nice weather.