Sometimes I think this world is obsessed with Core Strength. But then again, I am too. It's not about the six pack abs and tiny waistline because as your know Mr Iyengar had quite a beautiful round belly.
On the contrary it's about the human starfish. A student told me once she thought that strengthening her arms would help balance in crow pose. On the contrary, human starfish. Another told me how much he hates warrior 3 because it's just too hard and he always falls down. Again, human starfish. All the physical poses come down to this.
The human starfish is the principle of actively engaging the muscles in towards your center in order to energetically extend out through the limbs. Once you understand how to do this, you'll be able to find your balance and strength in an easy way without working so hard. I can't stress enough how important this is.
Try this: stand tall with your feet about 8 inches apart. Engage your transverse abs by pulling your belly towards your spine. Feel how that elongates your tailbone. Now draw the shoulder blades slightly towards one another and lift up through the top of the head while you maintain your strong belly. Extend your arms out to the sides and reach through your fingertips while you maintain the engagement of the shoulder blades. Feel your feet extend into the ground as if they're lengthening beyond the floor. Maintain while you take five slow and deep breaths. You are the Human Starfish!
Enjoy this 30-minute video to help drive the point home and strengthen your human starfishness.