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Why do we lock our knees?

Whether in yoga or simply standing and waiting, many of us have a habit of locking our knees. This is also referred to as hyperextending the knee joints, which is essentially pushing the knees back so far it reaches the end limit of the joint’s range of motion. Pushing the knee joint to this limit can place strain on the ligaments, tendons, and can also wear down the edges of the cartilage. Yet, when we lock our knees, there isn’t any pain, and in fact it feels effortless. This is because the damage to cause pain happens slowly overtime, and locking a joint actually requires less energy since there is less activation in the muscles than neutral posture – essentially we are riding on the structures of the joint to hold the position.

Locking the knees extends to a bigger picture of negatively affecting the whole body’s posture. When one area of the body is forced to an extreme, somewhere else in the body shifts to compensate to bring the balance back. When a person locks their knees in standing, this often forces the pelvis and spine to shift in posture. The image below shows two postural types that occur with locked knees: sway back posture and hyper-lordosis. Both can cause pain in the back (and neck) and eventually cause stress to the structures of the spine.

Unfortunately, locking the knees and the subsequent postural accommodations don’t just show themselves in standing still, they transfer to all our movements and activities, such as our yoga postures. Some commonly affected yoga postures are Triangle pose (Trikonasana) and the standing balance poses such as Tree (Vrksasana), and Dancer (Natarajasana) – see images below. By locking the knees in these postures, our alignment and safety is affected through the spine.

A Yoga Practice to Bring Awareness to Unlocking the Knees

Yoga provides us with a discipline from which we can learn to correct this habit and improve our posture. To bring more awareness to how we posture our knees start by practicing how you stand in Mountain Pose (Tadasana). In Mountain Pose, create a solid foundation in your feet: posture your feet straight ahead and ground evenly on all four corners of the foot. From your feet bring awareness to the posture of our knees, and if you feel them locked, practice generating a little give, or softness, to the joint (not bending, the legs still remain fairly straight). Then from the neutral knee posture notice how this affects your posture all the way up as you lift and lengthen.

Then choose a standing balance posture from which you can practice holding the knees in good posture, e.g. Tree or Warrior III (image above). As you challenge yourself on one leg you may realize that it’s not enough to feel softness at the knee joint, but also necessary to generate a sense of engagement of the posterior knee muscles to prevent the joint from pressing back.  

Then practice Pyramid Pose (Parsvottanasa) with the focus on the front leg and the posture of the knee. As you enter the pose, find your base by grounding evenly and firmly through all sides of the front foot and gentle press the big toe mound into the ground. From there, feel the line of activation that travels up the back of the leg to behind the knee. You are aiming to have the front knee straight without locking, and see if you can sense the engagement in the posterior knee muscles at the same time.
This pose is especially good because the posterior leg muscles are stretching, but we practice activating them in this lengthened position.