You probably won't be able to find a spinal muscle in that disused maze back there, much less mobilize one. As a hint, the muscles you use to arch backward when you have a backache are the very ones that lift the torso in the Cobra.
Now, just for the fun of it, try lifting the torso without putting any weight at all on your hands. You might even raise the palms slightly to prevent cheating. This will enable you to feel the muscles of the lower back and understand not only how weak or strong they are but recognize the "contact" that must be made to eventually go all the way up with spine strenght alone.
Whether you can lift five inches or no inches without weight on the hands, you do have your hands and arms to fall back upon. As a beginner you will make good use of them!
The essential point is to push that belly button through the floor with everything you've got, while arching spine, neck, head backward and releasing the small of the back. And glory in the stretch. Feel what it is doing for your waistline. Abandon worries about low-back pain and double chins. Your friend the Cobra has come to save you!
Do not collapse back onto the towel. Use your spine strength and arms to lower yourself smoothly,
This is not a hard pose requiring great strength or unusual contortions. You're not going to hurt yourself, you're not going to strain anything, there is nothing to fear. What the Cobra takes is will power - a commodity that is usually in shorter supply than strength. Barring medical problems, slow progress in the Cobra means just one thing - L-A-Z-Y!
The Cobra is one of the best ways to maintain the body in perfect condition. It increases spinal strength and flexibility helps prevent lower backache, and helps cure lumbago, rheumatism, and arthritis of the spine. It also relieves menstrual problems, cures loss of appetite, helps correct bad posture, and improves the functioning of the liver and spleen. The Cobra strengthens the deltoids, trapezius, and triceps.
Read more about this poses benefits, pictures, video and tips from HERE
Drawings and info from "Bikram´s Beginning Yoga Class " Book, 1978.