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Evaluating the System: There is no Right or Left

As we continue to learn more about how the human body functions, it has become commonplace to attribute movement dysfunction to isolated structures. “My left glute isn’t firing today, so I better sit on the lacrosse ball.” Perfectionists, as many of us in the field tend to be, we sometimes try to isolate and “fix” issues in the body by directly focusing on that specific area even though it may be somewhere down the chain that is the root of the issue. What we fail to grasp in most situations is that the body does not work in isolation, in fact, is works as one system.

“Our body is an elegantly designed and connected system, not just a bunch of individual parts that have nothing to do with each other.” – Dr. Mark Hyman

In a blog post a few weeks ago, “Do Asymmetries Matter? Part One,” we talked about the obsession with practitioners trying to find athletic symmetry in a world where it simply doesn’t exist. Practitioners are always trying to find the weaker or sometimes “dormant” muscles to ignite them or balance them without considering how these muscles function as a system during complex movement.

We have discussed this before as people are often intrigued as to how we can identify an increased injury risk for an upper body injury for an individual in a “lower body test,” (the vertical jump), or why we emphasize “lower body movements” such as a squat or deadlift as the best interventions. These classifications are a bit of a misnomer. Just as our bodies, and in turn the system of nerves, tendons, muscles, fascia, and other structures that support and create movement don’t adhere to the bodybuilding rule of the upper/lower split, they also don’t function in isolation as right and left sides. Simply said, the body doesn’t work left/ right just as it doesn’t work upper/lower; it works as a system. A complex system. 

For assessments, we utilize low-skill global measure to evaluate movement and asymmetries. Instead of testing for specific limb capacity or strength, we utilize unilateral measures for systemic balance and stability. We measure unilateral differences (R v L) using simple unilateral tests: the Balance and Plank Scans evaluate each limb separately, however, they have shown to assess more than just that particular limb. They assess the system as a whole.

In fact, through our internal analysis of the aggregate database of almost a million scans we have seen scores below 48 in both the Balance and Plank assessment show an increased likelihood of injury in more than just the limb assessed. In the Balance Scan a score below 48 has shown a 5x increased risk of knee injury, and a 2x increased overall risk of injury. Meanwhile, the Plank Scan T-Score below 48 has shown a 3x increased in risk of shoulder injury, as well as a 10x increased risk for concussion and groin injury!

The limb assessed is impacted, but the system as a whole is evaluated.

A perfect example is the football kicker showing a large difference in R v L on the Plank Scan. Because of the unique stiffness required on one side of the body to act as the anchor for the other side of the body to swing through at high velocity, it is no surprise to see a difference in each side assessed. The key is understanding that one side does not need fixed, or improved rather understanding the normative data unique to that position, and where they could be at risk.

These data points are not only reliable but are also valid as they are a more global measure of proprioception and stability. As is shown in the literature we have also identified functional asymmetries in different sub-groups, but we have taken the next step by creating actionable thresholds that are meaningful. For example, we know that baseball pitchers typically have lower plank scores on their throwing side, but yet don’t see any significant injury association based on the amount of asymmetry – only on a single side’s score being low (<48) relative to the database.


Once we identify a low T-Score below the threshold of 48 we need to have an action plan. What do I do when an individual has a Balance Scan of 42/45 (L v R)? The research has shown that movements such as the Quarter Box Squat and the Rear Foot Elevated Split Squat tend to improve the balance score in individuals. While we have our own theories as to why, the important thing is to have feedback loop for everything you do. If we know these movements improve global balance and proprioception we want to include them – and have a plan in place.

While no plan is perfect, we must understand that the process should be to always improve and refine our program along the way. To do this, a feedback loop is required which enables us to tweak our process to improve the health and efficiency of our athletes. There is no value in diagnosis without the ability to change the outcome, or at least attempt to.

Learn more about Planning here.“Plan – Scan – Repeat”

If you enjoyed this blog check out these:

Right v Left; It Still Doesn’t Matter

The Truth about Leg Imbalance

The New Linebacker: Don’t Measure Strength In Isolation