This post came up as an (expanded) answer to an email I got from a yoga teacher that follows me on social networks. I am always willing to answer any questions I can and am grateful when students and fellow teachers recognize me as someone they can address this type of questions. The question was about hollow back asanas, are they safe, who can practice them and who should not. 

So called hollow backs, a growing trend on (yogis) social networks, are variations of regular asanas with spinal extension (aka backbends) but with flexed hips. For example, Vrischikasana (scorpion) will become a hollow back if done with flexed rather than extended hips, Urdhva Dhanurasana will become hollow back if, again, you flex the hips (like on the photo) and so on. They look pretty and are photogenic, so they will serve as a good asana Instagram post, but are they safe, are they beneficial and what are pros and cons to this type of asana?

In anatomic terms, these type of postures are spinal extensions with flexed hips; something we see in some more traditional asanas like Uttkatasana, Ashtangasana and Matsyasana to name a few. However the named few aren’t considered to be deep backbends or advanced asanas and are generally safe. Hollow backs in Urdhva Dhanurasana, handstand or forearm stand is more advanced. 

So, what makes them different? In deep backbends like Urdhva Dhanurasana, Kapotasana, Ustrasana etc., we see the spinal extension accompanied with a hip extension. This creates a full opening of the front body, so not just the spine but also the hip flexors, which is an important difference. Hollowbacks only extend the spine. 

But, what's the problem with that? Well, two areas in our bodies which  are most affected by our, very sedentary ‘modern’ lifestyle, are our chest and our hips. Most people don’t walk much, don’t do much exercise and generally spend a great portion of the day in a seated position; in the office, in the car or any other transport, eating, socializing etc. This means we spend most of the day in a flexed position, with a flexed spine, hips and knees - physically and energetically closing our front body. I often refer to backbends as ‘counter poses to our everyday lives’ because of they open up the front body placing us in a position which counters the one we spend most of the day in. Backbends serve to balance out the constant repetitive movements of flexing.

If you flex the hips while extending the spine, as you do in hollow backs, you take out opening the hip flexors from the equation, a movement which is very beneficial to most of us. I am sure you have heard of the Iliopsoas muscle group, sometimes called ‘the muscle of the soul’. The importance of this group of muscles, their strength and flexibility is a topic for new post, but I am sure we all know how important it is to keep these muscles strong and open. Opening (extending) the hips together with the spine creates a nice arch in which different joints support the same movement. Less flexible yogis, or rather those with normal flexibility, might feel uncomfortable and ‘stuck’ in a hollow back backbend, especially the one done from Urdhva Dhanurasana. If you have tighter hip flexors, it's better to work towards opening them and releasing tension from that area extending the hips together with the spine. Also, as these type of asanas require open shoulders, I would advise caution if you haven't got a full range of motion in the shoulder joint or any shoulder issues.  

However, handstand against the wall with hollow back (buttocks and legs on the wall, hands away from the wall) can create a nice arch in the upper chest taking the extension out of the lower back which can be very beneficial for the upper chest area. If you feel tight in the upper chest or tend to pull your shoulders forward, this can be good for you. But, you don't need to go in a full handstand, you can practice the hands on the wall shoulder stretch first (Adho Mukha Svanasana on the wall). 

For more flexible yogis out there, I would even say those with hypermobile joints (again, new blog post coming up soon!;), hollow backs can teach them to get out of the lower back where they tend to go when practicing deep spinal extensions, but ONLY if they can keep the pelvis in neutral position avoiding anterior tilt. When done in proper pelvis alignment, hollow backs will create more space in the chest and avoid hyperextending the lower back.
So, if you are flexible enough and it feels good, no reason not to add a hollow back ones in a while in your practice. 

Generally, if something doesn’t feel right, don’t do it. As yogis, we should never lose sight of the true meaning of our yoga practice. Asanas are tools to heal our body, make it strong and clean. Advance asanas are tools to challenge us, teach us discipline, focus and control over our body and mind. But, we must learn these lessons one by one, step by step.
Never do anything that will feel painful and harmful to your body, mind and soul. Practice ahimsa, non-harming - ON as well as off the mat.