Let’s look at why this can be problematic, and how we can decide whether we, or our students, are hyperextending. (Hint, it’s not actually the knee we should look at!)
Hyperextension on its own is not necessarily bad for joints. However, it becomes potentially injurious when we’re bearing weight. In other words, if we were to simply straighten our knees as much as possible while sitting, we may hyperextend our knees. Because we are not bearing any weight, this will most likely be safe for the joints.
When we stand on one leg, as in balancing poses, we put all of our body’s weight on one leg. This doubles the load that leg is carrying making the force is much greater. This is where we can start to strain the tendons and ligaments behind the knee.
You can see in Examples 1 & 2, that the lower leg is at an angle when compared to the foot. You can then see in Example 1, that the knee is behind the foot. This is hyperextension.
If you compare this to the picture at the very top of the page, you can see that the shin is more or less, perpendicular to the foot. This is much more stable in balance, and will not put strain on the tendons or ligaments of the knee.
If you are wondering if you hyperextending, use this as your guide. If you are a teacher, look at the angle of the shin into the foot. This will guide you far more easily than looking at the knee. Finally, remember that hyperextension is something to keep a look out for when the joint is bearing weight. Whenever we are sitting or lying down, and not bearing weight, it is less of a concern.
