There are two different postural faults when it comes to the knees. Well really, there are a few more, but let me start by explaining one of the most common one's. When standing your knees should be straight, not locked.
Many people have been told to keep their knees bent when exercising. On the other hand, when just standing at your desk, just waiting for their to-go order to come out, they often lock their knees. Those moments when you are day-dreaming are just as important in regards to knee health.
I can tell you what my knees are doing, when no-one's watching.... they are locked. Because they are weak. Bummer!
The muscles, tendons and ligaments around the knee are supposed to stabilize the joint. As for me, I'm quite flexible. This is mostly genetic (genetically long and lax ligaments), but for some of that flexibility I've had to work hard (e.g. in the hamstrings), others not so much (lower back, knees).
If the muscles that are supposed to hold the knee are too weak, then there are only 2 options: Either, the knee will collapse (buckle). Luckily most of us have the mental control over our bodies, to not just collapse to the floor. The only other option for the knee is to lock, which puts it into a pseudo-stabile position (where the two bones that form the knee press against each other), but the knee joint will suffer the effects of my body weight after a while. Which I feel in form of pain.
In other people (e.g. cyclists, runners or anyone who's hamstrings have become very tight), the muscles on the back of the leg pull the thigh and lower leg bones towards each other, which bends the knee. If the muscles are never stretched out, then the knees will pretty much have a permanent bend in them. Which keeps the hamstrings tight and pulls the pelvis into a tucked position, which might create a problem in the hips, lower back or anywhere else in the body. Because (let's all sing along...) everything's connected.
Correct our knee position when we're standing is even more important when we're balancing on one leg. This, of course, means all our body weight is resting on one knee, instead of divided on two.
What I'm about to show you, is an extremely easy and quick fix, and practiced over time, will make sure your body stays healthy. Small things accumulated can have a huge impact.
Start By Intentionally Locking Your Knee
This means you'll push the knee all the way back (somewhat forcefully), until you feel that it can go no further. This might feel common to you (if your knees are weak, like mine, then you do this all day long). Or this might feel extremely uncomfortable to you, if your usual pattern is to keep the knees always bent. I want you to be aware of what this feels like, so you'll be able to tell the difference. If you want to take a look, stand sideways to a mirror. Can you see that the leg has a slight backwards curve to it.
Now Do The Opposite and Bend The Knee
Notice that it feels like the leg has a forward curve. Which it does of course. It just seems a lot more obvious in this position.
Now Bring The Legs Into a Straight Line
The knee will be in the center between the two previous positions, where it feels neither bending backwards nor forward. This is where your knee is straight, but not locked. It should feel like there is a line running vertically through the joint. It might not feel stable (yet), in this position, just straight.
Remember that the correct alignment or posture does not always feel right in the beginning. We perceive as right, what we have been living with for most of our life. In the beginning, you will need to pay a lot of attention to correcting this on a daily basis, until it has become second nature.
Here is one more cue to help you straighten the knee out of the locked position:
Resume the (wrong) locked position again, and then think of pushing the calf muscle against the shin bone. Or imagine someone is pushing against your calf with a lot of power and you are stabilizing the lower leg (you don't allow the knee to bend). Immediately, you should feel the muscles of the whole lower leg engage.
Try it and let me know how it goes. I'd be happy to answer any further questions in the comments below.
I promise I'll only send relevant stuff, and you can unsubscribe any time.