When I was doing my yoga teacher training in Bali last month, they showed a movie (and, forgive me, I don’t remember the name, but it had a bunch of slides of skeletons explained by a yoga guru with too many teeth), that discussed skeletal deviation and its effects on ability.
Our skeletons are as varied as any physical attribute. Our features, height, coloration, size of feet, etc., make up our unique appearance. We can see how different we are. On an athletic level, we can look at someone and identify them as a good sprinter with long legs or as having the shoulders of a gymnast. Genetically, certain people have a specific ratio of muscle fibers or a overall size/proportion that give them an advantage in some sports or training (I’ll write more about that some other time).
Our bones, like everything else about us, are specific to the individual. The shape of your pelvis, the placement of your hip sockets, and the length your femur all effect your movement patterns. Skeletal deviation is as normal as variety of hair color.
However, our bones are not as visible are our hair, and sometimes we assume that our skeleton should operate the same as the people training alongside us. It won’t. For example, if your hip sockets are forward facing, there’s a good chance that you will NEVER get your knees to lie flat on the floor in butterfly. Not matter how much you stretch. The shape of your pelvis won’t allow it. But if your sockets are on the side, you might be able to put your legs flat on the floor without getting any stretch at all. My person with forward facing hip sockets (me) has, likely, a better natural gait and is more predisposed to running and jumping in the sagittal plane. Mr. Side Facing Floppy Hip Socket is probably going to be a much more impressive yogi than I am (not that I'm bitter....).
Here’s another example: you know that stretch where you take your right arm up and over, allowing your hand to dangle between your shoulder blades, and then reach your left arm down and around, attempting to clasp your hands together? Google “Apley’s scratch test” if you have no idea what I’m talking about. Some people and give themselves this crazy reverse hug and tie themselves in knots. Other people cannot, under any circumstances, clasp their hands together. While flexibility likely plays a role in ability to achieve this ROM, the placement and size of the acromion process of the shoulder also contributes. It may be that, because of the nature of your bones, you will never be able to clasp your hands.
How do you tell if it’s bone shape or lack of flexibility? There’s a difference between stretch and compression. In a butterfly stretch—soles of the feet together, knees falling open—you should feel a stretch in the inner thigh and groin. If the sensation is located there, you have not reached your full stretch capacity and are still benefiting from the stretch. However, if you feel a kind of pinching, burning, or grinding on the OUTSIDE of the hip, that is compression, bone on bone. It means that you have reached the limits of your flexibility and are now compressing your joint. Stretch is the goal sensation (where you expect to feel it), compression is felt on the side OPPOSITE to the stretch. In Apley's scratch test, you should feel a stretch in the pecs and front of shoulder, if you feel pain in the back, around the shoulder blade, that's compression and you've reached your limit.
Why does any of this matter?
1. Compressing your joints is not great. If you can protect the joint by decreasing ROM, you are better off. Or, if you have bones and joints that allow for extreme ROM, you may need to find creative ways to deepen a stretch before you get any benefits from training flexibility.
2. YOUR FORM MIGHT LOOK DIFFERENT FROM SOMEONE ELSE’S. Expecting everyone to squat with their feet parallel makes no sense when you account for variation of hip socket placement or for femur length (for squats, take the stance that allows your knees to track over your toes). Don’t freak out if your body looks different while moving.
3. The maximum differs between bodies. My max butterfly stretch is not Instagram worthy, but it has taken a lot of investment and training on my end. I benefit from doing that stretch even if my knees will never lie flat on the floor. Conversely, someone else might have to invest extra time to running gait and knee tracking. You might reach your “best” without looking like the ideal. And that’s okay. Don’t be frustrated. This is why they x-ray ballerinas’ pelvises to see if they are going to be able to perform (their pelvis determines their capacity for turnout)—our skeletons create limits for us. Don’t blame yourself for not working hard enough when it’s just your bones. If you are moving in a way that makes your stronger or stretchier and it feels good, then you are good to go.