Healing Knees and Closed Chain Vs. Open Chain Exercises

This is a continuation of last week’s post, a success story with a twist near the end. Pat, who was suffering from knee pain, met a physical therapist who, upon hearing of how she improved by “walking small steps” around her apartment, approvingly said, “closed chain.”

So what are “closed chain” exercises, and are they the key to chasing away knee pain?

I had come across the closed/open chain terminology before, but never bothered to really look into it. Generally, I distrust geeks bearing jargon. I’m an Occam’s Razor kind of guy. When simple reasons explain phenomena as well as complex, why not keep it simple?

So I delved a little into the book, Closed Kinetic Chain Exercise: A Comprehensive Guide to Multiple Joint Exercise. I was far from an expert on the subject, but the same surely couldn’t be said of authors Todd Ellenbecker and George Davies.

Open-chain exercises, they tell us, isolate joint and muscle movements. Further, the movement pattern is “often nonfunctional.” And the “distal end of the extremity is free in space.”

To understand these points better, consider a pure open-chain exercise -- the seated leg extension (that’s the one in the gym where you straighten your bent leg forward, against the resistance of weights). The “distal end” of the limb (that would be your foot) is out there in open space, not fixed to anything. The exercise recruits only a few muscles and joints. And functionally, well, it’s pretty much useless, unless your daily activities entail punting a football repeatedly.

So that brings us back to closed-chain exercises (such as squats). Are they then superior? Sure sounds like it.

However, it turns out that things aren’t that clear. Here I’m just going to step back and let the authors of the book explain.

First, the functional vs. nonfunctional distinction doesn’t exactly hold up after all:

One of the common arguments against the primary use of open kinetic chain exercises in the lower extremity is that they are not functional. For example, there are limited instances in the lower extremity where an individual functions in a seated position bending and strengthening the leg ... Closed kinetic chain exercises are considered to be more functional, because they closely simulate the actual movement patterns encountered in both sport and daily activities.

Analysis of most functional activities reveals that they are, in fact, a series of successive open kinetic chain and closed kinetic chain motions. An example is the normal gait cycle. During walking, approximately 65% of the gait cycle is weight bearing (closed kinetic chain) and 35% is non-weight bearing (open kinetic chain). Interestingly, during running, the percentages of closed and open kinetic chain motions essentially reverse.

Further complicating matters:

Activities progress along a continuum from closed to open kinetic chain, with many activities of daily living and sport activities incorporating components of both. For example, during the gait cycle, the stance phase is a closed kinetic chain pattern, whereas the swing phase is an open kinetic chain pattern. Another example that shows the interplay between these two movement patterns is riding a bike, during which the foot is fixed on the pedal in a closed kinetic chain pattern, yet the pedal and foot freely move in space. Another example is skiing, where the feet are fixed to the skis (closed kinetic chain), but the skis move on the snow and are not fixed to an object (open kinetic chain).

What’s more, some purported benefits of closed-chain exercises may not actually exist:

Many clinicians have assumed that in the closed kinetic chain position of the lower extremity there is automatically a resultant co-contraction of the muscles that should dynamically stabilize the knee joint. Although some studies did demonstrate this phenomenon, several recent studies actually refuted that significant co-contractions occur with some closed kinetic chain exercises.

Finally, in conclusion, I found this quoted comment (my bold) from other researchers (cited as Snyder and Mackler; sorry I didn't get the full footnote) quite interesting. It refers to rehabbing after surgery to repair the anterior cruciate ligament, but I think the phrase “after reconstruction of the anterior cruciate ligament” could easily be replaced by lots of other phrases, such as “for patients with chronic knee pain.”

Rehabiliation after reconstruction of the anterior cruciate ligament continues to be guided more by myth and fad than by science ... The present study ... suggests that closed kinetic chain exercise alone does not provide an adequate stimulus to the quadriceps femoris to permit more normal function of the knee in stance phase in most patients in the early period after reconstruction of the anterior cruciate ligament.

Now if all this “open chain” vs. “closed chain” stuff sounds a bit faddish, well, the physical therapy trends (according to the authors) looked like this:

1970s Functional rehabiliation
1980s Open kinetic chain exercises (with emphasis on isokinetics)
1990s Closed kinetic chain exercises

How’s that for inducing whiplash? The same physical therapist you saw in 1985 who was saying, “You gotta do open chain, open chain, open chain,” ten years later was probably saying, “You gotta do closed chain, closed chain, closed chain.”

My personal take is that you need to do gentle, high-repetition activities (and if they’re functional, so much the better) to heal bad knees, giving yourself lots of time to achieve results. I wouldn’t worry too much about where my activities lie on the open-closed chain continuum.

Full disclosure: I own a bike chain. I like it. It gets me places. :)