Simplifying nutation and counternutation
Sacroiliac joint movement is often debated in the yoga world as well as the anatomy world. Many people equate what they feel is happening with what is actually happening anatomically at this complex joint. This is the beginning of a conversation here at yoganatomy.com.
Read the comments below as there is a significant amount of information there!
As a preface, there was an original question asking if someone could explain what nutation and counternutation actually were. And, they asked how those movements relate to backbending type postures such as ustrasana, kapotasana, and urdhva dhanurasana.
As often happens in the blogosphere, people comment. And in an effort to help, they sometimes add to the confusion. A student of mine from the D.C. area asked me to weigh in and see if I could simplify and/or correct what others were saying about this topic. There was some confusion between pelvic movements and sacroiliac movements.
Sacroiliac movements versus pelvic movements
I’m hoping that I can bring a little bit of simplicity to this conversation.
There are two movements that are getting mixed together here. First, there is pelvic tilting which is described as an anterior tilt and a posterior tilt. We define and discuss these from a neutral position, called anatomical position. That looks like someone standing upright, basically a tadasana pose.
An anterior tilt is when the pubic bone moves downward. Whenever this happens, we naturally make more of a lumbar curve, like a backbend. A posterior tilt is where the pubic bone rises or lifts. And, the opposite effect naturally happens in the lower back. We reduce the lumbar curve. These movements happen as the pelvis moves around the head of the femur.
Sacroiliac joint movements
Nutation and counternutation are movements that happen at the sacroiliac joint. The sacroiliac joint is where the sacrum meets the two sides of the pelvis. Nutation (from neutral again) is where the top part of the sacrum moves down and forward relative to the pelvis being fixed in place. Kapandji, referenced above, describes this as the sacral base moving forward and down. Counternutation is simply the opposite.
Everyone, unless their sacroiliac joint is fused, does some nutation and counternutation. The average person probably has, at most, somewhere between 3 and 5 millimeters of movement at their sacroiliac joint. In other words, not a whole lot. I’m surprised sometimes by how much emphasis is put on the idea of this movement happening in backbending type poses when such a small range of motion is possible at the sacroiliac joint.
How do these movements relate to backbends?
It is a good idea to consider all of the factors that go into a backbend and not get caught up in the part that moves the least. A good, or deep, backbend has much more to do with the hip flexors, such as quadriceps, adductors, and the iliopsoas, being open enough to allow the pelvis to move smoothly. When the muscles surrounding the pelvis allow it to move smoothly in backbending, it does not get jammed up in an anterior tilt and compress the lumbar region.
To clarify, since the question is regarding nutation and counter nutation, when you are in a deep backbend, your pelvis (relative to neutral) is in an anterior tilt. These forces will naturally put a force on the sacroiliac joint and if we look at the movement created there it would likely be counternutation. It is also possible for the sacrum to maintain its relationship with the pelvis. In that situation, if we took away all of the ligaments somehow, the forces on it would be counternutation.
Which movements can we physically create in a backbend?
This in no way speaks to what your intention is while in a backbending pose though. You might naturally try to undo some of the pelvic tilt, as people do when trying to tuck the tailbone under. This would be trying to tip the pelvis more into a posterior tilt from an already extremely anteriorly tilted position. So it’s not going to put the pelvis into a posteriorly tilted position because you’re not starting from neutral. If you do this, it would undo some of the counternutation and potentially allow the sacrum to nutate slightly.
People who are naturally flexible will have more movement at their sacroiliac joint. They may actually feel this, or control this movement better than the average person. I certainly can’t argue with anyone’s experience.
I also wouldn’t suggest that a student try to do this movement specifically. It will either happen or not happen on its own. However, if someone is dealing with sacroiliac dysfunction or pain, then pay more attention to how much or little of this movement is happening.