Bikram says that Cobra Pose is the most difficult posture for teachers to teach, and the most challenging posture for students to learn. If you find yourself confused in the posture, listen very carefully to the dialogue and try and execute each instruction to the best of your ability: five fingers together, legs together, palms flat, elbows 90 degree angle from the side, shoulders down, chest up, back should hurt.
This is one of the best postures you can do for back pain. When you do the posture the right way, you will find the sweet spot where your back “hurts.” Your back doesn’t hurt because it’s bad for you, but the pain is from the muscles surrounding your spine contracting so much. You want to achieve that contraction, and hold it as long as you can. Then, when you return to Savasana, the circulation rushes back into your spine like the opening Hoover Dam. This process, the tourniquet effect, will work miracles on back pain and is preventative medicine for your spine.
A healthy spine is a happy life!