Read Maty Ezraty's repsonse:
Teachers need to create a classroom environment that is safe and healing for all students. When a teacher has succeeded in doing this, students with physical challenges will feel comfortable doing variations or modifications while the rest of the class does the full pose. They will know what they need to do to take care of themselves and will therefore feel empowered. They will not feel singled out, but rather they will feel taken care of.
Creating this kind of classroom culture is a gradual change that requires a constant commitment from the teacher, and constant reinforcement of yogic principles. The philosophy of yoga and other topics, such as taking care of oneself, should be constantly woven into the class.
Shoulderstand and Headstand have many risks and therefore are best learned with props. I have found that this begins to promote a yogic culture. For beginning students and those who are stiff, blankets are very helpful. Using the wall can help students learning Headstand and Shoulderstand. Of course it is up to my discretion when my students can move away from the use of props. I find that this kind of order in my classroom keeps new students from feeling singled out.
Headstand and Shoulderstand may pose more challenges for some people who are overweight, but they are challenging for all beginners. And many overweight students are not challenged by these poses because, like other students, they did the basic work needed to practice them safely.
One variation is the Half Shoulderstand against the wall. This pose looks much like Setu Bandha Sarvangasana (Bridge Pose), with your feet up the wall. Again, use blankets to lift the shoulders. You may also want to learn how to teach Shoulderstand on a chair. These variations can be learned in Iyengar classes and can prove to be very useful with many students.
When students have difficulty doing Headstand, it is often due to weakness in the arms and shoulders. If the upper back and shoulders are not strong enough to hold the pose, pressure gathers in the neck. It may be useful to teach Dolphin Pose until students build up strength. Before attempting Headstand, the student should understand the proper work of the arms and shoulders. This can be learned with less danger in Dolphin Pose. Once the work of the shoulders has been understood and strength developed, then use the wall and go up to Headstand. The wall helps take some of the weight off the head and neck.
Another potentially challenging pose for an overweight student is Halasana (Plow Pose). However, when a student has difficulty doing Halasana, stiffness in the upper back and shoulders, and/or stiffness in the lower back and hamstrings, is often the culprit. It is hard to get up on the shoulders with a stiff upper back and shoulders, because it puts pressure on the cervical spine. Using blankets and a strap around the elbows will help take the pressure off of the neck. The belt will stop elbows from splaying. This and the use of the blankets will lift them up higher on to their shoulders.
When the student has tight hamstrings or lower back issues, it is difficult to bring the feet over the head into Halasana. The pose is more accessible if we use a chair or the wall.
For the student that you are describing, teach Halasana on at least two blankets, with feet against the wall. Place the blankets far enough away from the wall so that, when coming into Halasana, the feet are supported against the wall. If you have a Halasana bench, all the better. With the feet on the wall, it will be easier to get up onto the shoulders and set up the foundation of the pose, because you will have taken some of the work away from the hamstrings and lower back. It will become much more possible to create the lift needed out of the shoulders to be safe in the pose.
Maty Ezraty is co-creator of the first two Yoga Works yoga studios in Santa Monica, California. A former YJ Asana columnist, she travels around the world leading teacher trainings, workshops, and yoga retreats.