This is Ben. He is in training for his first marathon. He has no major concerns with musculoskeletal issues, but does have intermittent right medial knee pain, especially when increasing the mileage. Here is his run form initially:
The first thing that jumps out is the moderate toe out on the right side. The second thing from this angle is the asymmetry with arm swing and spinal rotation with left rotation being greater than right. My theory with this is that he is spending more time in the loading phase of gait on the right leg with a slow transition to push-off, thus his core is spending more time rotating to the left than the right. Here is another video of a test for ankle/calf/foot mechanics to see if that’s where the issue is.
It’s subtle, but notice how his right knee goes inward more than the left, as well as how his right hip has to rotate more than the left to accommodate the squat motion. This asymmetry lines up with what is seen with running. Also, if his right knee goes inward (increased valgus), this will cause repetitive stress on the MCL, pes tendons, and medial patellar capsule. This is the most likely culprit for his medial knee pain.
So here are a few exercises he is doing to work on calf/ankle/foot mechanics, as well as create better symmetry through the hips and core.
And since I can’t help but mess with run form a little, he also did a modified A drill on the treadmill.
After all this, here is a follow up video of his run after briefly performing these exercises.
Notice improved symmetry in the core and hips, as well as less toe out on the right foot. He will be doing these as a warm up for each run and hopefully will make another appearance to show off. Great job Ben and good luck with your training!