Skeletons are the framework for yoga practice. They are all uniquely proportioned and as yogis they define our individual limits. If your legs are much longer than your torso you will never be able to touch your nose to your toes in a forward fold no matter how flexible your hamstrings are. Or, if you come up against a hard 'bone on bone feeling as you move into to pose that is your anatomical end point. Hips are a key area where we can come up against this 'bone on bone' feeling and I'm going to explore the reasons in the remainder of this post.
Figure 1, below is of the top of two femurs (thigh bones). It shows the heads (which fit into the hip socket) and the necks attaching to the shaft of the femur, This picture is commonly used to illustrate the anatomical extremes of femur development. The bone on the left has a small head, and a long slim neck coming straight out from the shaft. The bone on the has a large head with a short thick neck, angled forward from the shaft. It's easy to see how these variations could mean different ranges of movement for the individuals involved. However, the shape of femur head and neck are only part of the story
|Figure 1. Top view of two femurs|
The shape and depth of the hip socket play a huge role in hip range of motion (ROM) as well. Figure 2.a, below shows scans from a hip imaging study . The blue shows a very shallow hip socket and the red a very deep one. Figure 2.b shows what happens to an individual's ROM when you take into account of the shape of the femur AND the hip socket. As can be clearly seen a shallow hip socket and narrow femoral neck allow a large ROM but with a deep socket and thick femoral neck the ROM is much reduced.
But what does this mean for us as yogis? Simply put if you have the hip configuration on the left you poses which require a lot of hip ROM e.g. pigeon or cow face are likely to be quite easy easy for you but you may struggle more with poses that require a lot of stability eg tree or warrior three. If you have the hip configuration on the right then pigeon may be very difficult but balancing on one leg might seem like the most natural thing in the world!
|Figure 2. a) Shallow and deep hip sockets. b) Hip ROM combining shape of the femur and the hip socket.|
The point here is not to beat yourself up one way or the other but simply learn to work with your body as you practice rather than trying to force yourself into a position that might simply be impossible for your body. Give yourself permission to modify alignment to allow for your body geometry. Good yoga teachers should understand and respect this (provided you are not doing anything unsafe!) and be happy to provide modifications for you if you are unsure!