This is Jeremiah, he is a stud high jumper and runner who has had right anterior knee pain, which is his jumping leg. Our discussion today is in the context of jumping, but the biomechanical principals certainly carry over to running as well. We didn’t take any footage of him running, but this video of a single leg squat tells us plenty!
There’s a lot that can we can draw from watching him do a single leg squat. As you can imagine, every time he jumps off his right leg, he has to load that leg in a squatting movement. The biggest muscle groups that are responsible for propelling upward to jump are the gluts, quads, and calf. So the question that helps us is, how do these muscles know when they have been loaded enough to propel him skyward? There are a few factors that go into the answer. In order to engage the foot and calf, the big toe and medial forefoot have to be driven into the ground to their end-range. In the video, you can see his forefoot pronate heavily, which causes his knee to fall inward rather dramatically. In order to push off, he needs to have a rigid forefoot to propel with, which happens at the end-range of forefoot pronation. Only when his forefoot reaches the end-range of pronation, do the bigger muscles further up the chain (calves, quads, gluts) get the signal that it’s time to push off.
I realize that became a little geeky with the biomechanics, but stick with me. What it boils down to for his knee, which is where the pain has been, is that when it comes time to push off, his knee is at an awkward angle, which means that the quads are pulling on the tendon (front of knee cap) from a direction that is dysfunctional and weaker. This causes increased stress on the tendon and certainly affects his ability to perform.
So, what to do about it. What is tough to discern from the video, is that structurally he has forefoot varus, which means that when his ankle and heel are in a neutral position, his big toe is off the ground. This is a common thing, and most people with this type of foot appear to be flat-footed. One of the first things we did is put a little pad under the base of the big toe. This will hopefully be a temporary measure to cause the forefoot to load more quickly and keep the knee in a happier position. We also did this exercise to encourage the whole leg to stay in more proper alignment. The pull of the thera-band forces his gluts to fire more quickly, as well as strengthens the medial quad (VMO), and helps teach the foot and knee to stay in better alignment.
As you can see, his foot has to struggle to keep proper alignment. It certainly will take some work to build a better habit with this. Here is another simple exercise to strengthen a foot that demonstrates these types of patterns.
Again, with constant practice to build strength and consistency, this will help keep his knee in better alignment and get rid of the knee pain. Keep up the good work Jeremiah!
These principles also carry over to running. If you think this may be an issue for you, watch yourself do a single leg squat in a mirror, if your knee is dipping inward excessively, you might respond well to these exercises as well. Let me know how it goes.