Pain in the posterior knee was a topic today while I was answering my forum. As I was answering the post, I realized that most people don’t understand how muscle memory will cause a muscle to stay contracted even when we want to stretch it, so I want to explain it here.
Muscle memory is a phenomenon where your body adjusts the length of a muscle to the length it has been contracted to for a period of time. So, when a muscle is contracted for a while, for example when you are sitting for an extended period of time, the body actually shortens the muscle fibers to become the contracted length and when you try to return to normal (in this case, straightening your leg), muscle memory says that the muscle is too short to allow the stretch.
There is a tiny muscle, called the popliteus, that is at the back of your knee. When muscle memory causes this muscle to stay shortened, you feel pain as you try to straighten your leg.
Your popliteus muscle originates on your femur (thigh bone) and crosses over the back of your knee to insert into your posterior tibia bone (shin bone). When the muscle is relaxed your leg is straight, but when you go to bend your knee your popliteus contracts to initiate the movement. The nickname for this muscle is “the key that unlocks the knee.” However, as you are sitting for a long time (ie: driving a car, or at your desk), muscle memory may shorten the popliteus and now when you try to straighten your leg it is pulling on the insertion points behind your knee.
You feel shooting pain in the back of your knee and it doesn’t relieve unless you bend your knee again.
The treatment is easy, but it’s a bit tricky to reach without some direction. If you already have my book, Treat Yourself to Pain Free Living, you can read how to do the self-treatment. This is one of the muscles that I don’t suggest you allow anyone else to treat because there are major nerves and an artery that passes through this space and unless the person is trained, you could have a problem. However, it’s safe enough for you to do it to yourself because you will only press when and where you feel the pain, so you’ll know you’re on the muscle and not one of the other structures.
Wishing you well,