Over on Facebook, R.B. asked me:

Recently, I’ve been unable to go running for more than 15 minutes without experiencing discomfort in my right knee (my dominant side). Even jumping causes some minor pain. It cracks a lot when I flex and extend it; so does the left side but not nearly as much as the right. From my preliminary research on the matter, I think I have “runner’s knee.” It may have to do with how hard I was training for a while (2x a day, running, weights, parkour, etc.) and then suddenly stopped the intensity for a couple of months this summer when I went to Brazil. Now that I’m jumping back into it, it’s been surprisingly difficult to find the right balance. Anyway, I guess my question is–do you have any suggestions (ie. exercises, readings, whatever) so I can get back to running while minimizing the likelihood of injury? I would greatly appreciate it

Before we begin, a standard disclaimer: I am NOT a physical therapist. I happen to know a lot about the body and I’ve solved this particular problem for myself and others. R.B., I would suggest that you consult a clinician, and take my advice with a grain of salt. That said, let’s go at it:

R.B was referring to a cracking on the inside of her dominant leg. This is most likely a malfunction of one of the muscles that connect the inside of the hip to the inside of the tibia on a spot called the pes anserinus, or “goose foot.”

Note that this is happening on her dominant side.

Let’s think systemically about this: Why is this happening? What problem is the body trying to solve?

Because the dominant leg is the one that supports the most weight, the body wants to bring it further in towards the center of gravity, i.e. towards the midline of the body. Imagine that you are supporting a wooden beam on two columns, but one is strong and one is weak. You’re going to want to put the strong column closer to the center, to support more weight. That’s exactly what the body is doing here:

It’s putting too much weight on the dominant leg because the non-dominant leg is too weak.

This is an example of a systems thinking concept: Shifting the Burden.  (In this case, the burden of supporting the body in an upright position is shifted from both legs onto the dominant leg). 

In order to manage that added burden, the body overuses the adductor muscles of the dominant leg, (which pull the leg towards the midline). And because the dominant leg doesn’t come out much (because it has to stay in to support the weight of the body), the abductor muscles, which pull the leg out, get very little work.

So, what happens is that you get adductor muscles which are too tight, and abductor muscles that are too weak.

Now, there are two answers to this question, and BOTH are important. The first answer is global: the system is developing a strategy of how to perform the function that R.B. is asking of it, and it’s putting too much weight on the dominant leg in order to perform that function. These kinds of sub-optimal strategies are what my favorite biomechanics bloggers, The Gait Guys, call a “compensation pattern.” As they like to say:

What you see in someone’s gait is not their problem, but rather their strategic compensation around the problem”

In order to see the most likely systemic problem, we have to cut across the whole body: if the muscles on the front outside of the dominant leg (abductors) are too weak, it is likely that the muscles on the rear outside of the non-dominant leg (primarily the extensors but also probably the abductors) are also too weak. Let me be clear that these are just the most likely culprits. It’s impossible to know specifically without looking at your particular case. The job of the muscles I mentioned is to hold up the leg—the very task that the non-dominant leg wasn’t doing well the first place.

R.B., I can’t give you a specific exercise for your non-dominant leg. That would be irresponsible on my part. But I can give you a general one:

The Gait guys have a cool abductor\extensor exercise that I think would be useful in your case (for your non-dominant leg). Here’s the link to the video.

What you could also do is this: during the same period (say 2-4 weeks) you are training the abductors of your dominant leg, also jump rope for a few minutes in the way I suggest. However, since you want to strengthen the extensors/abductors on your non-dominant leg, I would suggest that you emphasize jumping on your non-dominant foot. By that I mean that if you jump rope (with both feet) for a total of 6 minutes, jump 30 times on your non-dominant foot every minute.

You DON’T want your muscles to get too tired while doing this; you just want to get the non-dominant leg used to the motion of carrying your body alone.

Especially, you want the extensors/abductor muscles of your non-dominant leg to develop along with the abductors of your dominant leg. 

You should ensure that the relative strength of both relevant muscle groups stays constant, or you’ll create another compensation pattern.

Also the reason you want to jump rope during this period is to ensure that the strength is being incorporated into a motion pattern. It doesn’t matter how strong any of your muscle groups are if your body doesn’t know that they should be used as part of the holistic motion pattern. Getting them this motion pattern will allow you to eventually succeed on this task.

The best way to get the most bang for your buck out of this would be to jump rope after the training session for your dominant-side extensors/abductors. That way, they’ll be activated and slightly tired when you jump rope, so your body will be able to incorporate them into the motion much more easily.

Please put your questions in the comments; I’ll address them there.

Thanks for reading!

UPDATE: If something about running is difficult for you, or it’s difficult to get started running, there’s a comment thread going here.