Your knees are like the garbage disposals of your legs. They eat up what your hips and ankles can’t handle.
Let’s break down movement at the hip, knees, and ankles so we can make this crystal clear.
Once you understand how these joints interact, it will be easier to understand how many knee injuries happen and how to avoid them in the future.
The hips are the drivers of the legs.
When you think about it in terms of muscle mass, this makes sense.
Your glutes are the strongest muscles in your body, and they work to extend your hips so you can do things like get up from the toilet, jump, skip, and run.
Not only are they really powerful muscles, but they’re also required to have exceptional endurance for things like walking long distances.
The hips drive in another way as well; they direct which direction the legs move.
Think about this; if you’re standing and rotate your left leg to point your toes more to the left so you can start walking in that direction, where does the rotation movement come from?
It’s not the ankle, and it's not the knee.
The movement comes from the hip.
In other words, your hips are responsible for directing the movement of your legs because it has the most mobility and musculature available for the job.
What about your ankles?
Your ankles are also very mobile joints, but they work differently.
Instead of directing the leg with all of its available range of motion, movement at the ankle is used to adapt to how the foot comes in contact with the ground; think lunging vs. squatting vs. sprinting vs. climbing uneven terrain.
Now we have to look at your knees, and they’re playing by an entirely different set of rules than your hips and ankles.
Hopefully, you’re getting the jist that your hips and ankle are incredibly mobile. They can move in many different directions, and because of all the available movement options, the knee has to be different.
It needs to be more stable, and it is.
The knee is essentially a hinge joint; it flexes and extends.
It’s also the largest joint in the body, so it can take a ton of beating before things start to go wrong, and that’s exactly what happens.
If the hips or the ankles aren’t doing their jobs, the knee takes up the slack because it’s strong enough to take the beating.
If you squat and lack ankle flexibility to get into position, your knees will take the increased sheer force.
If you don’t have enough hip strength to maintain your knees following your toes as you run and change directions, your knees will accept the increased load.
Your knees can take the abuse and make up the slack, but they can’t do it forever.
Eventually, something gives out.
Sometimes it’s something relatively easy to address, like patellar tendonitis.
Sometimes it’s something more serious like an ACL rupture.
If you want your knees to “last,” your hips and ankles need to do their jobs.