Jaki Nett's reply:
The kidneys are located in the back body at the level of the floating ribs. Too much contraction there will affect the kidney area and sometimes cause pain. Start by examining Tadasana (Mountain Pose). Many times students use so much effort to find correct alignment in Tadasana that they exaggerate the actions and stiffen certain parts of the body. Encourage students to find softness at the lower ribs. To do this, bring attention to the muscles of the back. Ask these questions: Are the shoulder blades and the arms pulled back and down creating tension and hardness? Are the front lower ribs thrust forward? Is there intense gripping along the kidney area? Are the head and neck in a forward head position?
Then try Tadasana again, bringing the attention to the legs. Stand with the feet together. Spread the toes and the soles of the feet. The feet should be close enough to communicate but not so close that there is no room to spread. Look down at the side of the lower leg and make sure that the shinbone is perpendicular to the floor. Keeping its position, contract the kneecaps and align the thighbone with the shinbone. Balance the pelvic bones on the head of the thighbones. Place the upper body into the habitual Tadasana position. Now answer the above questions again. Take notes and then relax.
Try the pose one more time, focusing on the upper body. Keeping the legs and pelvis stable, relax the rib cage, shoulders, and arms. Soften the lower front ribs and move them slightly downward as you move the back ribs backward. Align the front lower ribs and the back lower ribs on a horizontal plane to each other. Release the grip that is pulling the shoulder blades toward each other and down. When the shoulders and arms are placed in their correct alignment there is a feeling of broadness across the collarbone as well as space between the shoulder blades. The head should be balanced on the neck so that the front of the neck feels no tension. When the head is correctly balanced on the spine, it demands the lift of the upper chest.
Also, remember that when you perform a backbend, you draw the vertebral column into the body. Try this in Matsyasana (Fish Pose)—make the action of arching the spine come from moving the vertebral column in, not just gripping at the muscles at the kidney area. Learn to take the spine into the body by using the back muscles.
To lessen pain in Savasana (Corpse Pose), place a bolster or rolled blanket under the thighs. Place the bolster at the buttocks and drape the thighs over the bolster. Then bend the knees and open the legs in Baddha Konasana with the feet on the floor. Let the lumbar spine rest on the floor. If the kidney pain persists, place another bolster across the abdomen to aid in the relaxation of the lower spine.
Try to keep the softness of the back body without losing postural alignment and the kidney area pain will subside.
Jaki Nett is a certified Iyengar Yoga instructor in St. Helena, California, and a faculty member of the Iyengar Yoga Institute of San Francisco. She teaches public classes in the San Francisco Bay Area and leads workshops in the United States and Europe, including specialty workshops on female issues.