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Tuesday, June 6, 2023

Introduction to Postural Dysfunction and Movement Impairment

Introduction to Postural Dysfunction and Movement Impairment
Brent Brookbush

Brent Brookbush


**Introduction to Postural Dysfunction/Movement Impairment


By Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, H/FS


  • Ideal Posture - Ideal arthro- and osteo-kinematics maintained by optimal myofascial activity and length, as a result of accurate sensation, integration and activation by the nervous system - both statically and dynamically.
  • Postural Dysfunction - The absence of ideal posture as a result of maladaptation by one or multiple tissues within the human movement system.
    • Example, rounded shoulder posture (RSP) and altered motion post surgical intervention for shoulder impingement syndrome (SIS), both result in compensatory patterns that may be termed "postural dysfunction." "Movement impairment" is a synonym for "postural dysfunction."

Dr. Brookbush demonstrated an Acromioclavicular joint Cross Body Special Test for Orthopedic Shoulder Objective Evluation
Caption: Dr. Brookbush demonstrated an Acromioclavicular joint Cross Body Special Test for Orthopedic Shoulder Objective Evluation

Special/Orthopedic Test for the Shoulder

Postural Dysfunction, Movement Impairment, Human Movement Science and Predictive Models:

The articles in the category “Postural Dysfunction & Movement Impairment ” are my attempt to refine previously published models of postural dysfunction and movement impairment. The goal is to improve the power of these models to accurately predict an optimal set of assessments, manual techniques, exercises, and outcome measures with the goal of improving posture, reducing the risk injury, enhancing sports performance and optimizing rehabilitation. As an educator, I believe these models provide an excellent foundation for building the skills needed to analyze movement, generate a hypothesis, select interventions and build a program/treatment plan based on that hypothesis. These models also aggregate 3rd party evidence (research), and may serve as an evidence-based foundation for the practice of human movement professionals.

"Postural dysfunction" (and synonym "movement impairment") most often refer to a methodology used by professionals in the fields of orthopedic sports medicine, and, more recently, sports performance, that sets the identification and correction of postural dysfunction as a primary objective. Although postural dysfunction models have been primarily muscular models, the Brookbush Institute (BI) aims to expand these models to include all tissues of the human movement system. The BI terms this an "integrated movement impairment approach."

"Human movement science" is related to this methodology and refers to the continued effort to understand both optimal motion and postural dysfunction. Defining "optimal motion" is often debated; however, researchers have done a better job of defining and correlating dysfunction with pain and injury. For example, knees bow in (functional valgus) has been correlated with knee injury and may be corrected with exercise (see Lower Extremity Dysfunction (LED) for a complete review of this example).

"Essentially, all models are wrong, but some are useful." - Box, George E. P.; Norman R. Draper (1987). Empirical Model-Building and Response Surfaces, p. 424, Wiley. ISBN 0471810339.

Models of dysfunction are often harshly criticized; however, most of this criticism is not appropriate given the purpose of a "model." Models are simplified representations of the world, and are therefore imperfect. However, models offer a chance to aggregate vast amounts of information, work through complex problems or create "generally" effective protocols without the time constraints imposed by the length of a single session or appointment. Further, the creation of a model may highlight gaps in our knowledge or the body of research, as well as a need for additional assessments, screens, interventions and modalities. Models may also highlight previously unconsidered relationships. It may be impossible to create perfect predictive models that explain all movement impairment, but that is not necessarily the goal. A predictive model of movement impairment should be viewed as a general theme that each individual expresses with subtle variations. The better the model, the more refined our approach, and the more effectively we can customize treatment for each patient/client.

Dr. Brookbush cues an athlete through the "Integration Exercise", Resisted Walking
Caption: Dr. Brookbush cues an athlete through the "Integration Exercise", Resisted Walking

Resisted Walking - Example of a lower extremity "Integration Exercise"

Prevalence of Postural Dysfunction

Determining the prevalence of postural dysfunctions would require a review and summation of all orthopedic pains, injuries, and pathologies, and the compensatory patterns correlated with those orthopedic pains, injuries, and pathologies. A quick review of the research would suggest this includes nearly everyone, many times over. This finding may seem a bit absurd until it is considered from the view of the individual. It does not sound absurd to say every individual will likely experience several orthopedic issues over a lifetime. A less intuitive finding is the fairly small number of compensation patterns correlated with the majority of orthopedic pains, injuries, and pathologies. These compensation patterns are discussed in the articles titled "Predictive Model of…..".

Although research investigating why these compensation patterns are so prevalent and predictable seems to be lacking; the subject warrants consideration (and hopefully future research). The hypotheses I have gathered/generated to date include:

  • Alternate movement patterns are pre-programmed in the central nervous system (CNS):
    • Vestigial patterns (evolutionary or developmental)
    • An alternate set of motor units recruited for continued performance (fatigue and/or injury)
    • Law of parsimony (over-reliance on low energy patterns)
  • Adaption to mechanical forces (many of these hypotheses should be considered with the assumption that gravity is a constant stressor):
    • Adaptation to mechanical imperfections and mal-alignments over time
    • Varying rates of tissue adaptation resulting in imbalance
    • Repetitive homogeneous stress leading to imbalance (sitting and typing)

The Evolution of Man

Constructing Models of Postural Dysfunction

The "model type" must be well-defined. The misappropriation or broad application of models often results in a false perception of inaccuracy and/or ineffectiveness. For instance, studies that oppose a postural dysfunction approach, commonly refer to a definition that is not the definition used by experts in the field, or a postural dysfunction model is applied to a scenario that does not match the patterns being modeled.

The Brookbush Institute's (BI) predictive models of dysfunction consider the quality of human movement as it relates to orthopedic injury prevention, movement preparation, and enhanced sports performance among recreational to professional athletics, as well as injury rehabilitation. The models are integrative, holistic, evidence-based, predictive, and practical. Professions and fields concerned with human movement are often dominated by differentiated, reductionistic, descriptive models of etiology. These differences are stark and intentional. The models the BI proposes are designed to aid in developing a strategy for intervention, although most models in the field only describe the symptoms, tissue damage, and contributing forces correlated with a diagnosis. Both are important, but cannot be compared. As a practical education company, the BI hopes that research leads to the integration of both model types. Until then the model which has the greatest chance to impact practice should be favored.

Each predictive model is constructed with the premise that understanding the common tissue changes (muscle, joint, fascia, and nerve) associated with each postural dysfunction will aid in the selection of an optimal set of assessments and techniques. This premise helps change the question, "What is the best assessment and technique for diagnosis x?" to "What is the best technique for addressing tissue "x," commonly exhibiting the maladaptation correlated with movement impairment "y"(which may be correlated with diagnosis z)". "What is the best technique for diagnosis "x"?", is a question that is so broad it would require an experimental design that included all possible populations and interventions, and combinations of those interventions to produce an applicable result. Although the question appears simpler, it is actually far more complex to answer. Creating a model of postural dysfunction results in "testable segments." For example, "What is the best way to inhibit a muscle assessed as over-active for those exhibiting the assessed movement impairment (e.g. Excessive Lordosis ) associated with a group of individuals with symptoms/diagnosis x (e.g. low back pain)?". Again, although this seems complicated, unlike the first study, it becomes a testable hypothesis investigating a relatively finite number of techniques. BI's predictive models of postural dysfunction were largely constructed by aggregating research with hypotheses that resemble the latter. Of course, as a model of practice, we have summarized and reduced the model into a "set of findings" that are practically relevant.

The models discussed in these articles were not designed to describe the compensation patterns adopted immediately post-acute injury or surgical intervention and were not developed with the intent of describing movement impairment related to neurologic dysfunction (e.g. stroke, Parkinson's, ALS, MS, etc.). Surprisingly, many professionals have reported that the corrective interventions implied from the models below have been beneficial for these populations. The BI does not believe that this justifies expanding these models to include these populations, but it may be evidence that acute injury, surgery, and even neurologic dysfunction may result in a set of condition-specific impairments, and additionally result in some compensatory patterns similar to those described by these models. The models below may also spark ideas for treatment (inferential reasoning) and present a repertoire of additional safe and effective interventions.

Forces contributing to an anterior pelvic tilt - Donald A. Neumann, “Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation – 2nd Edition” © 2012 Mosby, Inc.
Caption: Forces contributing to an anterior pelvic tilt - Donald A. Neumann, “Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation – 2nd Edition” © 2012 Mosby, Inc.

Forces contributing to an anterior pelvic tilt - Donald A. Neumann, “Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation – 2nd Edition” © 2012 Mosby, Inc.

What's In A Name:

All predictive models of postural dysfunction were named by body segment, as opposed to a pattern, joint action, diagnoses, or tissue maladaptation. This was intentional, as it allows the model to evolve without bias from the title itself. For example, "Lower-crossed Syndrome" may prompt researchers to look for "crossed patterns," while unbiased observers may find more symmetrical, spiral, or contralateral patterns. Conventional names for each postural dysfunction, and/or named dysfunctions that may be included in the model are listed and cited. For example, under Lumbo Pelvic Hip Complex Dysfunction , we note that "Lower-crossed syndrome" is a name that has been conventionally used, and that descriptions of altered recruitment patterns and motor control theory related to low back pain have contributed to the model.

Models of Postural Dysfunction:


Why evolve?

All models should evolve as science progresses and allows for the accumulation of more and increasingly accurate evidence. In human movement science, models of practice should evolve as new theoretical constructs, research, assessments, techniques, and outcome measures are added to the body of knowledge in the field. The Brookbush Institute (BI) model explains why theory, research, observation, techniques, and outcomes are interrelated and a hypothesis should be developed that results in each being true relative to one another a "Search for Congruence " by the Brookbush Institute. An attempt to find congruence between these various forms of evidence is one important implication of the word "integrative" when the "type of model" was described.

Four trends driving evolution:

  • A History of Evolution: Our understanding of the relationships between posture, dysfunction, and pain has been evolving for nearly 100 years. Early publications imply the medical community considered posture as early as the 1920s and 1930s. Such publications include Keith's, Hunterian Lectures on Man's Posture: Its Evolution and Disorders published in 1923 (10), and a 1936 paper by Ober (11) that not only mention posture but asserts that the iliotibial band may play a role in low back pain (perhaps the first account of "regional interdependence"). The late 1940s and early 1950s mark a turning point in practice and in the attention paid to postural dysfunction, improved posture was widely adopted as a goal of rehabilitation largely due to publications by Kendall and Janda (1, 4). Janda published the first defined models of postural dysfunction in 1979 (1), known as Upper-crossed Syndrome, Lower-crossed Syndrome, and Pronation Distortion (1). Further descriptions of common dysfunctions and approaches for correcting them were published by Lewit, Sahrmann, and others in the 1980s to early 2000s (2, 3, 5-9, 13). Dr. Mike Clark created perhaps the first "integrated systematic approach" to addressing postural dysfunction and movement impairment with various publications during his tenure as CEO of the National Academy of Sports Medicine (NASM) in the early 2000s (3, 13). Over the last four decades, an immense amount of research has been published related to movement impairments, bringing a new level of detail and accuracy to the discussion, and in my humble opinion, an opportunity to construct more accurate models.
  • Evidence-based Practice: The trend toward evidence-based practice as described by Sacket et al. (10) has spurred a demand for third-party evidence and support from published research. Although the texts cited above have ample bibliographies (especially in more recent editions), a need has been developed to refine postural dysfunction/movement impairment models based on all relevant research, including the most recent studies. As will be discussed below, the recent increase in research allows for a new level of detail in these models, and the addition of tissue dysfunction not previously considered. Although the models proposed by the BI are the most recent iteration, the models must evolve continuously to take into account recent research and developments and to maintain the highest levels of accuracy and relevancy.
  • Integration: No model, to our knowledge, has attempted to find congruence between muscle, joint, fascia, nerve and motor control based approaches. Human movement professionals have often mixed approaches in practice, i.e. soft tissue and articular based approaches, or fascial and motor control based approaches, but without formal analysis of the combination. If each approach is effective for different reasons (as implied by the varied intents), it seems logical that integrating approaches may have improve outcomes. Further, a model that considers all tissues may explain why all these practices are effective, at least in part or for specific conditions.
  • The Pursuit of Optimal Practice: Perhaps the most important reason for the continued evolution of postural dysfunction models is the pursuit of optimal practice. As human movement professionals it is our responsibility to pursue optimal practice until every aspect of the human movement system, performance, its impairments and pain is known, along with a full understanding of all conservative rehabilitation, exercise and strength and conditioning techniques.

To advance is not divine inspiration, but addition to the body of work that preceded us.
Caption: To advance is not divine inspiration, but addition to the body of work that preceded us.

“We are like dwarfs sitting on the shoulders of giants. We see more, and things that are more distant, than they did, not because our sight is superior or because we are taller than they, but because they raise us up, and by their great stature add to ours.“ – Isaac Newton

Levels of Analysis:

"When right, I shall often be thought wrong by those whose positions will not command a view of the whole ground" - Thomas Jefferson

The quote above captures a familiar feeling from presentations and courses teaching an "integrated movement impairment approach." The in-fighting among human movement professionals who hold different certifications and prefer one modality to another is well known. It is common for every professional to argue that his or her method is the best and that only one method (or maybe two) can prevail. This is a logical fallacy that assumes human movement is a zero-sum game, and that the inclusion of one technique must exclude others - despite the obvious fact that approaches and techniques may be used together. In an integrated approach, the professional will take Thomas Jefferson's position and will "…view the whole ground." What the BI has found most amazing in the study of human movement science is not the contradiction between approaches, but how well most approaches fit together. Following are the "levels," that refer to the various ways movement impairment is analyzed by the Brookbush Institute.

  • Comparison, Observation, and Logical Inference: This methodology considers the common excessive joint motions noted during dynamic/transitional postural assessments. From the commonly noted "excessive joint motions," alterations in muscle length may be inferred, and lists of "long (lengthened)" and "short (tight)" muscles may be created. This algorithmic approach to the analysis of postural dysfunction will also be compared to the traditional (Janda) models of postural dysfunction (1).
  • Research on Related Impairments (Evidence-based Osteokinematic Analysis): Each model could be defined as a combination of movement impairments commonly cited in research. For example, Lower Extremity Dysfunction (LED) includes a loss of dorsiflexion , functional pes planus , feet turn out , and a functional knee valgus . The term "functional" is used here as an adjective describing altered motion that is not caused by a structural change or congenital abnormalities. Because research is ongoing, a review of the research on these movement impairments is used to refine the observations and logical inferences discussed above. Research demonstrating relationships between joints (regional interdependence) will also be discussed.
  • Research on Individual Structures (Evidence-based Muscular, Fascial and Articular Analysis): The BI has aggregated relevant studies on the individual muscles, joints and fascial structures related to each postural dysfunction. This step is likely the most important in refining a model constructed and defined by the traditional model, logical inference and evidence-based osteokinematic analysis.
  • Correlation with Diagnoses and Orthopedic Pathology: Much of the research related to postural dysfunction/movement impairment investigates how common pathologies affect function, quality of motion and muscle activity. This inevitably results in a list of diagnoses that may be correlated with postural dysfunction. The number of studies showing that dysfunction precedes pathology, pain and/or acute injury is growing, implying these models may be predictive of future pathology, pain or injury, as well as optimal intervention.
  • Practice and Outcomes: The Brookbush Institute prides itself on being a practical education company. This model is constantly refined by the effect interventions have on patient and/or client outcomes, based on objective and reliable assessments. "Clinical effectiveness" is a heavily scrutinized term due to inherent bias, so we will spend little time discussing the positive impact our work has had on our patients/clients, students, colleagues and their patients/clients. We will discuss specific cases in future articles, with the intent of describing individual diagnoses and symptoms, how predictive models of dysfunction are applied, and presenting ideas for working around challenges faced in "real life" practice. The table (summary of model) at the beginning of each predictive model article is constructed with "practice" in mind, and has been influenced by our successes and failures in applying these models.

By Giovanni Alfonso Borelli - De Motu Animalium book, Public Domain, https://commons.wikimedia.org/w/index.php?curid=12370371
Caption: By Giovanni Alfonso Borelli - De Motu Animalium book, Public Domain, https://commons.wikimedia.org/w/index.php?curid=12370371

By Giovanni Alfonso Borelli - De Motu Animalium book, Public Domain, https://commons.wikimedia.org/w/index.php?curid=12370371

Analysis by Logical Inference:

Although each article covering a predictive model of dysfunction will detail how this level of analysis was applied to the model, the general method is discussed here because the application and method is used in all models. In each of the models of dysfunction, this level of analysis has been based on the common observations noted during the Overhead Squat Assessment (OHSA) . Although this may seem to place considerable weight on a single assessment, the OHSA is more of a cluster of assessments/signs that may be reliably identified during a common movement pattern (squat/sit-to-stand transfer). Further, it has been our clinical observation that the signs and impairments noted during the OHSA for a given patient/client, are generally observable during many transitional/dynamic assessments including gait, stair-climbing, jumping, etc. (17). In summary, the OHSA is a gross movement assessment that adds reliability to the observation and assessment of postural dysfunction, and could be replaced by any other movement assessment that is as reliable. Further, the steps described below could likely be applied to many different assessments.

  • Reliability of the OHSA: Initial research on the intratester reliability and intertester reliability of the OHSA has shown to be "good to excellent"; however, the current research available is limited to lower body signs (16 - 23). This is sufficient for Lower Extremity Dysfunction (LED) , but is a weakness when discussing the OHSA relative to other predictive models of postural dysfunction (Upper Body Dysfunction (UBD) , Lumbo Pelvic Hip Complex Dysfunction (LPHCD ) and Lumbosacral Dysfunction (LSD)) . Three noteworthy findings relative to reliability and the OHSA include; reliability in identifying a pattern associated with a higher risk of ACL injuries (functional knee valgus ) (16), a correlation between pronation and frontal plane translation of the tibia (20), and two studies demonstrating a correlation between the overhead squat assessment and restrictions noted via goniometry (22, 23)

Analyzing Postural Dysfunction/Movement Impairment: Conceptually, analysis of postural dysfunction/movement assessment is not complicated; however, the accuracy and detail of the analysis is dependent on your knowledge of functional anatomy. The analysis starts by examining the joint position and the effect this has on relative muscle length. The following instructions and sample table can be used to analyze any dysfunction, and have been in the articles Overhead Squat Assessment: Signs of Dysfunction and Overhead Squat Assessment: Sign Clusters and Compensation Patterns :

  1. Establish an ideal to compare motion to; that is, know what "good posture/movement" looks like.
  2. Identify the excessive joint action that resulted in the deviations/sign(s) observed.
  3. List all muscles that will contribute to that joint action(s); these are "short muscles."
  4. List the opposing joint action(s).
  5. List all muscles that will contribute to the opposing joint action(s); these are “long muscles."

5 Steps for Analyzing Dysfunction:

Sample Analysis from the article: Overhead Squat Assessment: Signs of Dysfunction

Feet Flatten = Excessive Eversion

Note: This compensation pattern is often driven by a lack of dorsiflexion

Short/Over-active Long/Under-active
Evertors: Invertors:
Plantar Flexors: Dorsiflexors:

Teacher's Note:

  • Initially, it is important to use an organized strategy for analyzing dysfunction. I view the process above much like solving an equation, and I often refer to the process as "doing our math" in the courses I teach. For most of us, common uses of math include bills, adding sets and reps, getting change, etc. As long as you know general algebraic functions (+, -, /, x), have a piece of paper, and a calculator, and give yourself adequate time, you can find the solution to fairly complex problems (for example, your monthly budget, quarterly budget or potentially your taxes). Similarly, if you use the methodology above, determine the corresponding joint action for the deviation at each joint, write down the muscles associated with those joint actions (you can use an anatomy text or BrentBrookbush.com when necessary) and use a piece of paper to list all of the muscles of altered length, you can build a corrective strategy regardless of the number of deviations or the complexity of the compensation pattern. In the case of postural dysfunction, you will note that there are a fairly small number of possible dysfunctions (solutions tables). Practice will lead to memorization of these dysfunctions, the muscles involved in these dysfunctions, and the techniques recommended for each muscle. Given enough time you will notice sign clusters, also known as compensation patterns . Further practice will lead to building sample programs, circuits and flows for each dysfunction that will be refined by day-to-day practice.

Overhead Squat Assessment demonstration of the sign "Feet Flatten". Dr. Brookbush demonstrates the excessive motion noted at the foot/ankle complex with his hands. Break down of the short and long muscles on the white board behind him.
Caption: Overhead Squat Assessment demonstration of the sign "Feet Flatten". Dr. Brookbush demonstrates the excessive motion noted at the foot/ankle complex with his hands. Break down of the short and long muscles on the white board behind him.

Future Scope:

I hope you have enjoyed all of the articles covering predictive models of postural dysfunction. I believe it is the first attempt at a comprehensive integration of a postural dysfunction/movement impairment with osteokinematic, muscular, fascial, myofascial synergy, and arthrokinematic-based approaches. Further, I hope it is the most thorough review of relevant research in pursuit of an in evidence-based, integrated movement impairment approach. If you take a moment to review the bibliographies for each article you will notice they are divided into sub-categories to make reviewing or gathering the research on any topic addressed in this article as easy as possible. It is my sincere hope that readers will have suggestions for additions to the bibliography, or alternate interpretations of the research cited as we continue to pursue optimal practice. Although these articles have been updated many times, there is still plenty of work to be done. Future scope:

  • Addressing issues described in the current models:
    • The issues listed at the end of each “level of analysis (Osteokinematic, Muscular, Fascial, Myofascial Synergy and Arthrokinematic)” will require further research, and in many cases new research methods (technologies, techniques, and research design). Our collective industries have become more than a little impatient, often asserting that a lack of evidence is a sign that the negative is true, but that is a fallacy. We must be open about gaps and weaknesses in the current body of research, open to considering new hypotheses, support the researchers working hard to find the answers, and simultaneously be patient enough to allow the research to be done and published. We may even need to be patient enough for new technologies to develop. At this point, we still have no way of monitoring the development of a motor plan in the CNS, investigating the reflex arcs associated with release techniques in vivo, only crude methods of measuring changes in arthrokinematic motion, and fascial adaptation remains largely a topic relegated to slides under a microscope. But, imagine what the next two decades will reveal. Advancing technology assures with near certainty that we will be able to monitor smaller and smaller changes (perhaps even at the cellular level) with minimally invasive techniques, in real-time, and likely at less cost (Moore’s Law may apply here).
  • Additions: Nervous System:
    • Neurodynamics: In the future, neurodynamics should be added to this model. My initial investigation into this topic can only be called cursory, but I have seen enough to be excited by the implied relationships between nerve entrapment/restriction, over-active muscles, fascial changes, and altered biomechanics. This will likely be the next level of analysis added to each model.
    • Nociception: Understanding which tissues possess the greatest likelihood of contributing nociceptive input may aid in understanding why certain diagnoses are so common, the extent of regional interdependence (i.e. how ankle dysfunction can lead to hip pain and not ankle pain), what techniques may be most effective in initial stages to reduce pain and fear avoidance movement patterns, and perhaps most important, may serve as a bridge to overarching theories of pain science (e.g. Mature Organism Model (MOM), Biopsychosocial Model (BPS), Cumulative Injury Cycle, etc.). Perhaps the most obvious and immediately applicable research to add to this model is a thorough understanding of trigger point development and prevalence.
    • Pain Science: This branch of medicine has grown exponentially in the past decade, but at this point can only offer vague implications about practice. That is, it is not clear how pain science models refine intervention selection, clinical decision-making, or progressive treatment plans. This may be too myopic a view of pain science, as pain science may offer a better explanation of “how” things work, rather than “what” should work. In either case, the consideration of pain science must be included in an integrated model of movement impairment, if the model is to be a comprehensive integration of approaches.
  • Math
    • The more accurate and comprehensive a model of dysfunction becomes, the more likely it is that the model can be expressed mathematically, and further be used to predict values. These values may include forces on tissues, rate of tissue adaptation and maladaptation, forces necessary during interventions, probability of injury given a set of impairments, injury with the highest probability given a set of impairments, the correlation between treatment and resolution of impairment, etc. Although this may all seem to be a geek-out for math lovers, the implications are far more practical and inspiring. This type of math could predict the best set of exercises for a set of symptoms, or the best set of interventions based on a video-captured movement assessment. If these exercises/interventions can be predicted, they can be video recorded and sent to the individual being assessed. The more accurate the model, the more individuals could be helped in this way. This could lead to anyone, anywhere, getting good therapy for a wide range of diagnoses, at incredibly low costs and with no more technology than is offered in a smartphone. Although it may not work for everyone, just imagine if this allowed 80% of diagnoses to be resolvable by a set of exercises that someone could do at their desk during their lunch break. What impact could that have on medical costs, productivity, and quality of life? The closest I have been able to come to the equation that explains the general relationships is:

Work x Time x Impairment = Pain/injury

  • That is the risk of pain or injury increases with increased impairment (a measure of displacement from optimal), increased workload, and increased duration of time (in weeks or months). In this equation pain/injury is set at a critical value of tissue damage that results in the “perception of threat.” “Work” could likely be represented by a variety of researched models of volume and workload, or potentially be replaced by Power. If replaced by "power" would time be canceled out simplifying the relationship? “Impairment” requires a numerical scale to be created that is proportional to the available range of motion at each joint and associated with the risk per "percent displacement."


  1. Phillip Page, Clare Frank , Robert Lardner , Assessment and Treatment of Muscle Imbalance: The Janda Approach © 2010 Benchmark Physical Therapy, Inc., Clare C. Frank, and Robert Lardner
  2. Shirley A Sahrmann, Diagnoses and Treatment of Movement Impairment Syndromes, © 2002 Mosby Inc.
  3. Sahrmann, S. (2010). Movement system impairment syndromes of the extremities, cervical and thoracic spines. Elsevier Health Sciences.
  4. Michael A. Clark, Scott C. Lucett, NASM Essentials of Personal Training: 4th Edition, © 2011 Lippincott Williams and Wilkins
  5. Dr. Mike Clark & Scott Lucette, “NASM Essentials of Corrective Exercise Training” © 2011 Lippincott Williams & Wilkins
  6. Florence Peterson Kendall, Elizabeth Kendall McCreary, Patricia Geise Provance, Mary McIntyre Rodgers, William Anthony Romani, Muscles: Testing and Function with Posture and Pain: Fifth Edition © 2005 Lippincott Williams & Wilkins
  7. Karel Lewit. Manipulative Therapy: Musuloskeletal Medicine © 2007 Elsevier
  8. Keith, A. (1923). Hunterian Lectures on Man’s Posture: Its Evolution and Disorders: Given at the Royal College of Surgeons of England. British medical journal, 1(3251), 669.
  9. Ober, F. R. (1936). The role of the iliotibial band and fascia lata as a factor in the causation of low-back disabilities and sciatica. JBJS, 18(1), 105-110.
  10. Sackett, D. L., Rosenberg, W. M., Gray, J. M., Haynes, R. B., & Richardson, W. S. (1996). Evidence based medicine: what it is and what it isn’t. Bmj, 312(7023), 71-72.
  11. Clark, M. A. (2001). Integrated training for the new millennium. Thousand Oaks, CA: National Academy of Sports Medicine.
  12. Donald A. Neumann, “Kinesiology of the Musculoskeletal System: Foundations of Rehabilitation – 2nd Edition” © 2012 Mosby, Inc.
  13. Leon Chaitow, Muscle Energy Techniques: Third Edition, © Pearson Professional Limited 2007
  14. David G. Simons, Janet Travell, Lois S. Simons, Travell & Simmons’ Myofascial Pain and Dysfunction, The Trigger Point Manual, Volume 1. Upper Half of Body: Second Edition,© 1999 Williams and Wilkens
  15. Cynthia C. Norkin, D. Joyce White, Measurement of Joint Motion: A Guide to Goniometry – Third Edition. © 2003 by F.A. Davis Company
    • Reliability
  16. Hewett, T. E., Myer, G. D., Ford, K. R., Heidt, R. S., Colosimo, A. J., McLean, S. G., & Succop, P. (2005). Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes A prospective study. The American journal of sports medicine, 33(4), 492-501.
  17. Buckley BD, Thigpen CA, Joyce CJ, Bohres SM Padua DA. Knee and hip kinematics during a double leg squat predict knee and hip kinematics at initial contact of a jump landing task. J athl Train 2007;42:S81
  18. Vesci BJ, PAdua DA, Bell DR Strickland LJ, Guskiewicz KM, Hirth CJ. Influence of hip muscle strength, flexibility of hip and ankle musculature, and hip muscle activation on dynamic knee valgus motion during a double-legged squat. J Athl Train 2007; 42:S83
  19. Gribble, P. A., & Robinson, R. H. (2009). Alterations in knee kinematics and dynamic stability associated with chronic ankle instability. Journal of Athletic Training, 44(4), 350-355.
  20. Trimble, M. H., Bishop, M. D., Buckley, B. D., Fields, L. C., & Rozea, G. D. (2002). The relationship between clinical measurements of lower extremity posture and tibial translation. Clinical Biomechanics, 17(4), 286-290.
  21. Mauntel, T. C., Post, E. G., Padua, D. A., & Bell, D. R. (2015). Sex differences during an overhead squat assessment. Journal of applied biomechanics, 31(4), 244-249.
  22. Noda, T., & Verscheure, S. (2009). Individual goniometric measurements correlated with observations of the deep overhead squat. Athletic Training and Sports Health Care, 1(3), 114-119.
  23. Bell, D. R., Padua, D. A., & Clark, M. A. (2008). Muscle strength and flexibility characteristics of people displaying excessive medial knee displacement. Archives of physical medicine and rehabilitation, 89(7), 1323-1328.

© 2017 Brent Brookbush

Questions, comments and critiques are welcome and encouraged.