Don’t blame genetics. Don’t blame your age. And please, don’t blame your knees.
They’re the victims here.
When you run or ski, you put a ton of load through your legs – easily 4x your body weight – and your knees have to transmit those forces to your hips.
Which works fine, when your hips work right.
But all too often, hips aren’t strong enough to stabilize all the forces coming into the knee – especially lateral (side-to-side) forces.
And those lateral forces, when they go into the ACL and MCL without support of the muscles of the hip, cause untold injury.
Great for surgeons and PTs. Bad for you.
It’s no accident that the biggest muscle of the human body – the glute max (your butt) acts on the thigh, and therefore, on the knee.
But unfortunately, it doesn’t mean that glute max, or the rest of the muscles of the hip, are working well. Glute med., quads, hamstrings, inner thighs, calves, and more – ALL need to work in concert to keep the knees working well.
And knees that work well, feel good, and can last a long, long time.
It can be as simple as a pair of exercises, one for the outer hip, and one for the inner thigh and hamstring.
For the hamstrings, use the single-leg deadlift ( https://www.youtube.com/watch?v=QzCDvIQPFr4 ). 5 sets of 8 per side is a great place to start.
And for the outer hip, use the pausing goblet box squat ( https://www.youtube.com/watch?v=i-qSL7ze_RE ). 5 sets of 10 reps is a good start.