Originally Posted by chillywater
"Quads" or quadriceps hold the knee in place. Strong quads=strong knees.
The quadriceps don't hold the knee in place.
They extend or straighten the knee.
Four ligaments hold the knee together while also allowing it to move: the medial collateral ligament (MCL); the lateral collateral ligament (LCL); the anterior cruciate ligament (ACL); and the posterior cruciate ligament (PCL).
Ligaments connect bones to bones and allow movement while keeping the bones in proper relationship to each other.
If a seated person straightens one of his legs, he has extended his knee.
Conversely, when he bends his knee, he has flexed his knee.
We have four main muscles in the front of our thigh, hence the "quad" in quadriceps.
When we extend our knee, we do so (in most situations) by shortening the quadricep mucles in the front of our thigh.
One of the quadricep muscles runs all the way from the front of the hip bone to the front of the shin bone via the quadriceps tendon.
The other three quadricep muscles run from the femur, or thigh bone, to the front of the shin bone, also via the quadriceps tendon.
For a picture of the four knee ligaments and the quadriceps tendon, go here:
All four muscles attach to the quadriceps tendon, which runs over the knee cap and thus to the front of the shin bone, or tibia.
In regards to the quadriceps tendon, the kneecap (patella) serves at least two functions.
First, it gives the quadriceps tendon a better angle on the shin bone, for extending the knee; and, secondly, it redirects some of the force into
the knee (pushing the knee backwards) instead of up
on the shin bone.
Check out this picture, and it might make more sense:
Bookmark the above in your mind and let's discuss pedaling for a moment.
We all learned to pedal by mashing.
With flat pedals and conventional shoes, we had no other choice except to mash down on the pedal.
The first skill we learn regarding any activity becomes the file within which we place the skills we learn afterwards.
We call this primacy of learning
Everything we later learn about pedaling goes into our "mashing" file.
We mash by default, and only with conscious practice do we fill in the rest of the spin with effective work.
We mash by extending our knee.
We extend our knee by shortening the four quadriceps muscles (one of which runs all the way from the hip bone to the front of the shin; and the other three run from the thigh bone to the front of the shin).
As the quadriceps muscles pull up on the shin bone to extend the knee, they also push the knee cap back into the knee, so that all the forces work to force the bones of the knee together.
Gravity pushes the knee end of the femur down into the knee joint; the quadriceps pull the shin bone up into the knee joint; and, the quadriceps push the knee cap back into the knee joint.
With mashing, all the forces come together in the knee: up, down and back.
However, another method of extending the knee exists, which does not so much involve the quadriceps, but which makes use of the many muscles in the hip.
These muscles move the thigh bone (femur) forward, backward, left, right, and twisting.
These hip muscles would move the thigh bone even if we cut off the lower leg at the knee.
In fact, these hip muscles wold move the thigh bone even if we removed the quadriceps muscles.
And, for our purposes, these muscles could pedal the bike even if we removed the quadriceps muscles.
If we had only our hip muscles (and no thigh muscles), as long as our foot remained connected to the pedal, the hip muscles could pedal the bike by simply moving the thigh bone up and down.
The knee, then, would serve only as a passive hinge.
The four knee ligaments would hold the knee together and, in concert, the bones and the ligaments would perform as a hinge.
Gravity would still place a load on the knee hinge, but the quadriceps muscles would no longer pull the shin up into the joint, nor push the kneecap back into the joint.
By transferring some of the work from the quadriceps to the hip muscles, we remove two of the three loads on the knee; thus giving our aching knee more of an opportunity to heal.
How do we transfer some of the work from our quads to our hip muscles?
We can pre-organize the coordination of the various hip and leg muscles by "visualizing" bringing our knee to the handle bar as we pull up on the pedal during the back part of the spin.
Our knee will still follow the same path regardless of what we "visualize," but by imagining ourselves trying to hit the handlebars with our knee, we activate those portions of our brain that control the hip muscles; so that, as our foot goes over the top of the spin, we have our hip muscle brain centers pre-loaded and ready to push the thigh bone down during the "mashing" portion of the spin.
We will still "mash" with our quads, but, because we have recruited more help from the hip muscles, we will not "mash" as much with our quads as we usually do; and, thus, we will lessen two of the three forces working in our knee.
As for saddle height, over-extending the leg due to too high a saddle brings its own set of miseries.
It may feel good and extra-efficient, initially, to pull up with a fully-extended leg, but, this can put a huge load on the two internal ligaments, the ACL and PCL "cruciate" ligaments.
When we do this, we have a sense of a "swollen" knee, especially in the back of the knee.
Where our knee hurts can tell us a lot about the mechanism of injury.
Does the knee hurt on its inner side, where the two knees brush together?
Or does the knee hurt just below the kneecap, and, does it hurt just below the kneecap on the inner side, the outer side, or the center?
Or, does the knee hurt on the top of the knee cap?
We actually have seven different common manifestations of knee pain, all with different causes originating in body mechanics.
As for fitting, we can do two things that will at least set us up for less passive injuries.
Find your kneecap with your fingers.
On the inside edge of your knee cap, on the side towards the other knee, find the place where your shin bone and your thigh bone come together.
Or, follow the place where the shin bone and thigh bone come together, and follow that line until it bumps into your knee cap.
Note that place where the two leg bones and the knee cap come together on the inside side of the knee, and mark it with a pen or your memory.
Take a long piece of string, a coin and two pieces of adhesive tape, like scotch tape.
Tape one end of the string to "the place" on your knee and tape the other end of the string to the coin.
With you bottom in the saddle and the cranks horizontal with the subject foot forward, the string hanging from your knee should pass through the spindle of your pedal (and the spindle should pass underneath the ball of your foot and big toe).
Move your saddle fore or aft in order to get the string to pass through the pedal spindle.
As for saddle height, with the pedal in its full down position, your bottom on the saddle, and your heel as low as you can get it, you should still have a slight bend in your knee.
Move the saddle up or down so that, with the pedal at full bottom, seat in the saddle, and heel full down, you still have a slight bend in your knee.
Move the saddle fore and aft so that a string hanging from "the place" passes through the pedal spindle.
Get the relationship of your saddle to your pedals correctly adjusted and then start working on other knee things.
If my description of "the place" doesn't make sense, tell me and I'll try again, with pictures.