Motor Patterns and Pathologies – Installment #5


By David Lemke


Upper Quarter Observations

In installment 3 I listed some lower body complaints and conditions and pointed out the importance of the body’s asymmetrical core. I suggest reading that entry if you haven’t already.

My goal here is to present to you how a common dysfunction underlies a multitude of complaints. I want to share how I believe this common dysfunction is a normal consequence of the body’s core asymmetry.

The Case that brought me to Kinesiological sEMG

In 1993 I was treating a gentleman who had suffered injuries in a high speed rear-end collision. The crash happened seconds after he pulled into a highway rest stop. Another driver, thinking it was an exit off ramp, drove full speed into his parked car.

I had been working with him for nearly a year – with intermittent success – at which point he sought help from a local (Calgary) physician who was using multi-channel kinesiological sEMG to locate trigger points. This physician provided me with his sEMG data hoping it might assist with his treatment program.

The first thing I noticed in his sEMG tracings was that the serratus anterior (SA) was not active on his left side.  When I included SA manipulation in my usual parascapular treatment, his relief was dramatic. Being the thorough investigator (obsessive/compulsive) I am, I began including SA manipulation in all my shoulder clients’ treatments (I had several at the time). To my delight I observed consistent improvements rather than the often short-lived improvements obtained previously. This gentleman experienced great relief that was lasting and his life was able to return to normal.

At that point I knew I was on to something. And, of course, I believed all I needed was to understand why treating serratus anterior made such a difference – then I would possess the key to the shoulder complex (alas, I was a younger man then). Imagine how thrilled I was shortly after this when I began training with sEMG and was able to perform my own testing!

The Trouble with Normal

Since the original “test” case I have tested hundreds of individuals presenting with a wide variety of pathologies and complaints. However, I have also tested many normal, functional individuals – often athletes with no complaints – just healthy people with a desire to perform better. I was most surprised to find that these normal people showed up with their left serratus anterior, posterior deltoid and lower trapezius not activating well. And their right glut max and left medial hamstring also not activating at levels on par with their contralateral cohorts…

This led to the question: what if the human motor system is predisposed to apparent dysfunctions because it is influenced by factor(s) common to everyone? So, rather than thinking I was dealing with problems, I began considering more normal influences. This led me to take a fresh look at handedness and fetal position (flexion pattern) dominance. I started looking at these factors more as biases steering an ever-adapting and learning system. This opened the door to using manual treatment to counter the effect of constant forces driven by these biases. I was literally using manual therapy methods to reduce / minimize handedness and flexion dominance – like cross-training to counter an overuse pattern!

By reducing inhibition of extension pattern muscles and improving the strength symmetry in muscle pairs, I saw a dramatic reduction in symptoms associated with a wide variety of complaints – everything from headaches to neck and shoulder pain to mid-thoracic pain. I also received reports back from my client athletes that they were achieving personal bests and/or overcoming barriers to higher performance. All this without focusing on complaints!

UQ and the Core Pattern

As a general rule, clinicians acknowledge that hand dominance exists however, they essentially ignore it and let it have its way. They almost universally provide exercise and therapeutic interventions which are, for the most part, applied symmetrically unless targeting a one-sided condition or pathology.

Note: A major study conducted more than twenty years ago found a nine to one ratio of shoulder instabilities on the non-dominant side1. My sEMG testing seems to indicate the same thing: instability in the left rotator cuff in nearly every subject!

Of course the temptation (and the general practice in orthopedics) is to say that an unstable rotator cuff is a pathology. But let’s keep focused on the instability as part of normal function and see where it takes us…

Why the Left Rotator Cuff Becomes Unstable

Why the left rotator cuff is unstable is both vital to correcting the dysfunction – and vital to how we approach many other issues as seen in the chart below.

A physician (a client at the time) sat right in front of me looking at her sEMG tracings on the projector screen and asked:

“Why would my left rotator cuff be unstable? I never use it.”

My answer: “Exactly”.

It took a few minutes to explain to her that body parts, unlike tractor parts, do not sit neatly on the shelf wrapped in plastic waiting to perform perfectly the moment they are put to use. In the human body we lose what we don’t use. And in a pathologically self defensive, “always on”, learning and adapting system, loss of strength and stability must be compensated for – which is why a weak left rotator cuff can be the root of many other issues.

Below is a list of common upper body pathologies / complaints I believe are tied to weakness in the left rotator cuff.

lemke graph

When we look at mechanical distress in the body, we tend to more readily consider traumatic causes: dramatic imbalances and parts completely damaged or disabled. I hope I have caused you to look more carefully at “acceptable” imbalances or asymmetries as not simply falling short of optimal – but accounting for much of the adjustment the body must constantly make – and which undermines a robust, injury immune physiology.

It is imperative that we use technology that measures as accurately and reliably as possible – and that we appreciate unbiased data even when it causes us to question our models. In fact it has been the problem data that has forced me to look deeper. The benefit of  looking deeper for me is that I now see an adapting, learning system steered by predictable defensive biases. These biases are always involved to some extent in a very long list of problems. Fortunately, for those who know what to look for,  they can be measured and studied. And if better understood, then countered, injuries and pathologies can be reduced and ultimately prevented.

There is too little space in this entry to share how I work to correct the left rotator cuff weakness. However, I will introduce some of my approach to treatment and exercise in a future entry. The working title of that entry? “There’s a reason they’re called dumbbells”.

1. Warner JJ, Micheli LJ, Arslanian LE, Kennedy J, Kennedy R: Patterns of flexibility, laxity, and strength in normal shoulders and shoulders with instability and impingement; Am J Sports Med. 1990 Jul-Aug:18(4):366-75.