It is likely that you either know or know of an athlete who has sustained an ACL tear. I don’t need to spend much time going over the struggle that the athlete has to endure in order to fight her or his way back onto the field or court following surgery. Just know that it sucks. Big time. I have gone through it myself and I have helped many high school and college athletes through it.

 80 percent of ACL injuries are non-contact and generally occur when landing, changing direction or cutting. You would think that such a debilitating injury would have to be caused by a high-speed collision with a 300-pound monster, but no, a simple mistake in mechanics at the wrong time can cost an athlete 9 to 18 months.

 How does this happen?

To keep it simple, a lack of strength in the glutes and feet coupled with poor landing and/or deceleration mechanics can put the knee in a very compromised position upon landing or changing direction. Snap.

Before we get to the knee itself we need to touch very briefly on some of the science behind movement.

Force is what creates movement. If you are standing still you are creating just enough force to resist gravity, otherwise you would collapse. When you take a step forward, you are creating enough force to resist gravity AND move your body forward through space.  The faster you attempt to move and the higher you attempt to jump, you create more and more force.

Ground reaction force is the force exerted on the body by the ground. We exert force on the ground and the ground exerts force on us. The force that the ground exerts on us is where we run into trouble.

When you land on 1 leg, it is estimated that the force the ground exerts on us can range from 2 to 18 times your bodyweight. For a 150lbs. athlete with a ground reaction force of 8 that would be 1,200 lbs of force that the leg has to safely absorb. Think about that.

Now that we have a grasp on what the knee has to deal with when landing, changing direction or decelerating, lets think about the knee and all the messed up stuff we do to it!

Think of your shin bone and your thigh bone as a marriage with ligaments such as the ACL holding it all together. As with any marriage, our actions can bring on harmony or a sh*t ton of marital discourse! The ligaments keep the knees in a healthy alignment. When an athlete lands, cuts or changes direction, the ground forces can cause the shin and thigh bones to slide infront of, behind or to the side of the other which strains the ligaments as they stretch to hold it all together. This is where a tear can occur. This is kind of like a spouse who forgets your birthday year after year. Athletes need to land, decelerate and cut with an adequate amount of ankle dorsiflexion, knee flexion and hip flexion in order to prevent abnormal movement of the knee.

 In part two I will go over what we can do to help prevent or, at least, lessen the frequency of these injuries!