Knee pain while squatting and ankle mobility issues are linked. By doing the assessment on the video you’ll be able to stay safe by knowing what is safe.
The most functional movement of the ankle is dorsiflexion. Dorsiflexion is when the top of your foot approaches the front of your leg. You need proper ankle dorsiflexion when walking, running, jumping, lunging, and squatting. If the ankle doesn’t have full function compensation will work its way up and your knees will not be fully supported during squatting. The two common squat faults that occur and devastate your knees are:
1.) The knees migrate inward: This is the most vulnerable position for the knee and the reason why coaches always cue “knees out!” During the descend phase of the squat, your knees need to be able to track directly over your feet. One of the ways the body can cheat the movement when ankle dorsiflexion is limited, is by bringing the knees in to then track forward. This creates dangerous torque and an unstable position that will certainly lead to injury over time.
2.) The flexion break a.k.a. the butt-wink: This is another example of what your body can do when the center of gravity is shifted, because of the lack of ankle mobility during squatting. The knee joint is protected from shear loads due to the co-activation of the muscles in the front of your thigh (quadriceps), and the muscles in the back of the thigh (hamstrings). This co-activation maintains the right amount of compression on your knees during the squat movement. If your knees can’t advance forward and you don’t let them migrate inward, as you descend down, your center of gravity will shift back from your midfoot. In order not to fall back you will be forced to tilt the pelvis and flex the spine forward. Tilting of the pelvis slackens the hamstrings and you’ll create shear loads on your knees.
The loss of dorsiflexion is just one of the many reasons why poor squat form and injuries occur. However, it is one of the most important and often overlooked. Without proper ankle function there will undoubtedly be compensation up the kinetic chain. Stay safe by knowing what is safe.