I have never had a problem with urdhva dhanurasana.
But I have had lots of students who have or do have difficulty with it.
One thing I always emphasise is the spine should not feel squashed at any part or at any point from ground to lift and down again.
People can tend to squash in their lower backs.
I have even had people tell me they thought it was supposed to squash their lower back.
I tell people they are practicing something else but not the pose I am trying to teach if they feel squashing.
If you are in my class I want you to remember a few things when it comes to this part of the sequence.
Practice without squashing.
Don't be attached to the outcome.
With this in mind, a part of not being attached to the outcome is realising you don't need to do anything at all if it does not feel right.
You certainly don't need to come all the way up.
With this in mind, I made a poster that shows what you could pay attention to if you decide not to push your hands into the floor. There is still plenty you can do and, in fact, I do these things each time I come up into a fuller posture, as you can see in the video at the end (it's just that I only need to spend about a second getting there whereas some people will need more time).
Please bear in mind this post is intended primarily for my students who can experience what I am teaching in a class situation. Learning this type of thing from the internet is not suitable.
Read the poster from the right starting with what to do with the knees.
If you lie on your back and just press your feet into the floor you will feel your pelvis get light without necessarily lifting. Then press your knees over your toes.
The pelvis will lift and be carried towards the heels. I am not trying to push my pelvis up here. There are many styles that teach this and it is possible and there are benefits to that as well but it is not what I am doing here.
I then reach my arms as far away from my pelvis as possible. I try to basically get as long as I can through my body--pelvis moving one way and armpits the other.
Then I try to billow up my chest as though a gust of wind has blown through my feet and hits me in the middle of my upper back causing it to lift.
This is where I like to get people to stop and think for a while. Moving this part of the spine is really tough. It is the stiff part of most people's spines.
Many people cannot get movement in this part of their spine at all unless I provide a tactile cue (touching the area). Often people shove their pelvis up and down and their chest moves as a consequence but there is little to no independent movement in the upper spine.
What I am trying to do for myself when I practice this way is get some independent movement of the chest so that my spine does not move as one chunk.
It is delightful just to try to raise and lower the chest here without moving the pelvis and just continue reaching the arms in one direction while moving the knees in the other.
But you decide.
Don't do anything that hurts or strains.
Most people will need to do a lot of 'warming up' before they can do the full version of the pose but you can do this modified variation any time.
Having said that, my teacher Paddy always taught me that they should feel so free you can do the full posture first thing in the morning when you get out of bed. I do that myself every now and then. I am not saying I don't feel a bit stiff in the morning but in my experience she is right, when you are able to move freely then this is possible. Being able to move freely takes a lot of practice though and I still have stiff mornings!
Also, when you practice this way there should have been no squashing so no need to do something to unsquash your back afterwards.
Below is a video of the full thing, taken on location in Sri Lanka at my last yoga retreat. I will be heading there, by the way, for my next yoga retreat from 1-4 October 2015. Get in touch if you'd like to join us!
This post is not intended to cover all of the aspects of back bending. I wanted to emphasise a pose you can try on the floor without raising to the full posture that helps you lengthen. There is, of course, much more you can do within that even (did I mention doing a sit up in your tummy?), but that is for class!
Happy and safe practicing.