“Pull up your knee caps and thighs” my Astanga Vinyasa teacher used to say repeatedly, back in the 1990s. I dutifully did as I was told – and more. The effect in my case, was hyperextension of the knees – the very scenario the instruction was intended to prevent. When I realised that the soreness in my knees was partly caused by this action, I began ‘micro-bending’ instead. Over time, this had a similarly irritating effect.
Another common and controversial instruction for the knees in yoga classes is “don’t lock your knees” but occasionally the instruction is the opposite “lock your knees!” What sense can we make of these conflicting ideas? Yoga teachers mostly have the best intentions, so it’s likely that all these instructions were originally given to help students have healthy alignment. Subsequent to my knee locking and knee caps lifting Astanga experiences, I sought out teachers who expressed concepts for alignment with more subtlety and nuance. From Donna Farhi I learned to find conduits for force to flow through. She says, for example, “as force flows along the bones and across the joint spaces….” From Erich Schiffmann I learned the premise of ‘lines of energy.’ From Amy Matthews I learned to find pathways of weight. 
I also learned from Amy that locking the knees can be functional and healthy. When a leg straightens and the knee fully extends, there will be a little medial rotation, a little spiral of the femur on the tibia. This little extra rotation that happens at the very end of knee extension, seats the medial femoral condyle clearly in its meniscus on the tibia. This is called physiological lock. The physiological lock takes place just in the knee joint, it isn’t the same as hyperextension, which is likely to involve both the knee and the tibia moving together. There’s a little muscle in the back of the knee called the popliteus, which helps to undo the physiological lock towards flexion.
Regarding the ‘knee caps and thighs lifting’ instruction, Amy confirms what experience taught me – that it doesn’t prevent hyperextension of the knees and in fact can cause it. However she talks about hearing in past Iyengar classes the instruction “Draw up the space behind your knee cap“. At first she thought this was just a fanciful idea. Then she learned about a nifty little muscle called the Articularis Genu – which if you don’t know Latin, means articulation of the knee. The Articularis Genu is a deep muscle located underneath the quadriceps, it attaches to the front of the femur and to the joint capsule of the knee. The patella (knee cap) is embedded in the joint capsule, so although the Articularis Genu doesn’t attach to the patella, when it concentrically contracts, it draws up the joint capsule, which in turn pulls on the patella – mainly from the inner surface (in other words from behind the knee cap).
In teaching alignment for a straight leg, the aim should be for an up/down trajectory so that the weight/force can travel through. There should be no forcing. It is really important to me that my students find healthy alignment in their knees. I tend to give instructions such as ‘find the place where the weight can travel through‘. I often demonstrate the principle by showing how my elbow can hyperextend and explain that it wouldn’t be great to take weight through that elbow. Donna talks about avoiding ‘breaks’ in order to arrive at healthy alignment. A hyperextended elbow or knee are an example of a ‘break’. I also sometimes say ‘see if you can find a gentle lift from behind the knee cap’, and ‘as if your knee caps and thighs are smiling’. Finally, ‘your knees should feel snug‘.
What of my own knees? Well, when there’s pain it’s rarely a simple, straightforward matter. It turned out there was a lack of rotation in my upper body during normal walking – probably a tension habit from childhood. I’ve studied somatic approaches extensively over many years; in amongst those studies and experiences, I eventually fathomed that my habitual walking pattern subtly interfered with the alignment in my knees. These days my knees are mostly happy. And when I pause in standing with knees extended (and snug), I enjoy feeling a clear pathway of weight to the ground – creating a greater readiness to deal with the world!
Happy practising!
PS The Somatic practices I’ve trained in are Integrative Bodywork and Movement Therapy and Embodied Anatomy with Amy Matthews – the latter has especially informed this post
