Low back pain (LBP) is a common problem. Chronic LBP is a leading source of worldwide disability and a cause of staggering health care costs. According to a recent World Health Organization (WHO) bulletin authored by Traeger et al,¹ it “is the single biggest cause of years lived with disability (YLD) worldwide,² and a major challenge to international health systems.” The traditional biomedical model is incomplete and has led to poor management of the LBP patient. In fact, Traeger et al¹ state there is strong evidence that unnecessary care, “including complex pain medications, spinal imaging tests, spinal injections, hospitalization and surgical procedures, is hazardous for most patients with low back pain.”^3,4,5

We need to update the biopsychosocial (BPS) approach considering the multitude of factors that make up the patient experience. Because pain is multifactorial, rather than focus on a single cause of pain, it is better to acknowledge the complex systems at play and develop an agile approach to handling uncertainty.

Given the multifactorial nature of the LBP problem, a question posed by a multidisciplinary group of experts is “what potential is there for identification of individual biomechanical factors to play a role in treatment of LBP?”⁶ They state, “Our numerical and analytical simulations of multifactorial presentation of LBP demonstrated that if a large number of factors contribute to an individual’s LBP, any treatment strategy that seeks and treats the most dominant factor is less effective than treating any 2 or more factors chosen arbitrarily.⁷ Furthermore, the probability of identifying sub-groups, that might respond favorably to a specific intervention in such a population, tends to zero as the number of factors increases.”

The challenge of LBP is the difficulty in confirming either the specific pain generator or source of biomechanical overload in the kinetic chain.⁸ Thus, most LBP is reluctantly considered to be nonspecific.⁹ This does NOT mean there is no cause, only that LBP has a complex etiology with multiple pain sources and perpetuating factors.^9,10,11

In spite of this limitation, a diagnostic triage can still be performed. Diagnostic triage is a scientifically proven approach that classifies pain sources in the following way (see Chapter 3):

Red Flags—approximately 1%

Nerve Root—approximately 10%

Nonspecific LBP—85% to 90%

Although the ability to provide a specific diagnosis is limited, an outcome-based approach benefits from screening for yellow flags (YFs), which are risk factors of chronicity^3,4,5 (see Chapter 7). Patients with either nerve root or nonspecific LBP with YFs benefit from a cognitive-behavioral (CB) approach (see Chapter 16).⁸ CB education, therapy, or training focuses on
affective (i.e., emotional) or cognitive (i.e., beliefs and behaviors) factors (see Chapters 13 and 16).¹² The goal is to screen and intervene in a person-centered way in order to reduce threat of pain or reinjury and enhance self-efficacy.^8,12

Taking a thorough history is an essential first step in creating the patient profile (see Chapter 37). This idea is nothing new, but has been underestimated and underutilized in previous models. Understanding the patient’s story, creating a therapeutic alliance, and inspiring the patient to take an active role in care rather than being a passive recipient is the cornerstone of this approach. The clinician should be able to gather information about the patient’s goals, fears, worries, beliefs, and concerns, as well as activity intolerances (AIs). All patients require a diagnostic triage to rule out red flags of serious disease. Although necessary, this is not sufficient to properly manage the case. It is also essential to identify the patient’s YFs indicative of a poor prognosis. Finally, the clinician should establish baselines for a patient-centered rehabilitation by identifying the patient’s current capacity, required capacity, and demands.

Patients with nonspecific LBP should be reassured that they don’t have red flags, a nerve root problem, and given functional reactivation advice consistent with CB principles.^3,4,5 Commonly, it is believed that such advice ignores the person’s pain or suffering. In fact, properly administered patient education explicitly creates therapeutic alliance and provides reassurance (see Chapters 13 and 16).

A novel strategy that recognizes the heterogeneity of patients utilizes the Pain Mechanism Classification System (PMCS) (see Chapter 9). The PMCS’ appreciation of the role that psychosocial aspects play in the pain experience means that clinicians need to develop a skill set that reflects the ability to assess and manage pain mechanisms that are influenced by psychosocial as well as biologic factors.

The physical examination including orthopedic examination, neurologic examination, and movement assessment is utilized to gather further information about the patient’s mechanical sensitivities (MSs), painless dysfunctions, and current capacity. In musculoskeletal care for the individual in pain, goal setting and outcome measures play a critical role in allowing practitioners the evaluative tools to demonstrate change to patients and third-party payers.

When the painless dysfunction that is nested to the chief complaint has been identified, the clinician can begin to guide the patient through movement prep (MP) targeting this weakest link. During movement, pain is monitored but not feared. Teaching the patient that every hurt does not equal harm is a key lesson the clinician can provide to allow for the individual to have a positive experience with movement. The clinician guides the patient through movements when there is some pain (<3/10), using caution during movements with moderate pain (4-5/10), and changing the exercise when there is pain (more than a 5/10; see Chapters 9, 37, and 38). The MP gives way to training general physical preparation (GPP), working the fundamental movements of squat, hinge, single leg bias (e.g., lunge), push, pull, and locomotion (e.g., carry). Understanding that every exercise is a test allows the clinician to constantly be auditing to find the hardest thing the patient does well.

Proper load management is important in building the robustness and resiliency necessary to ensure that capacity is greater than demand. Using a constraints-based approach, consistent with Dynamic Systems Theory (DST), varying the task and environment creates an opportunity to develop adaptability in the individual so they will be able to respond to unpredictable stress and become antifragile.

To this point, the approach has been entirely active. This creates autonomy and independence for the patient and in many ways is essential to the updated paradigm. Although manual therapy is not lost, it should be limited to an as-needed basis to enhance recovery and reduce delayed-onset muscle soreness. Whenever possible, manual therapy, modalities, medications, and injections should be utilized only if MP and GPP are poorly tolerated and when CB is occurring simultaneously.

The solution is to realize that there are general principles that can highlight a path toward “pattern recognition” or the precision necessary for offering patient-centered or individualized care pathway. Principles also allow health care practitioners (HCPs) to insert whatever skills and tools they know now and integrate others in the future, thus enhancing all current and future tools. The four principles outlined in Chapter 38 allow the HCP to be both evidence based in general and agile enough to personalize a precision approach.

Each patient needs

This framework allows for a step-by-step efficient process that can be applied to any patient to bridge the gap from what they have (capacity) to what they need (demands). Rehabilitation is a time-consuming process and thin slicing is needed, otherwise patients will not stay engaged long enough to get the results they want and need. The rehabilitation prescription, rather than being a protocol based on pathology or symptoms, is a precision process following economical yet potent principles.

According to Dan Pfaff, “it’s about landmarks not timelines.” So we give people hope by finding reversible functional pathologies that give people both hope and an achievable plan. This is done to help them become more PREPARED because “it’s not the activity that’s harmful but the activity you’re not prepared for.”¹⁴

Naturally we address the YFs such as the belief hurt = harm and that activity is harmful. This is key to reconceptualizing pain and danger versus safety signals. Deimplementing scare tactics about their imaging pathology and giving them a positive experience with movement builds their self-efficacy so they are less PROTECTIVE.

Establish trust to build movement confidence by identifying painful activities and then training around pain using our principles.

Three steps

Lower back and neck pain were the leading global cause of disability in 2015 in most countries.¹⁸ This was verified by the Global Burden of Disease Study covering 1990 to 2017 data.¹⁹ Noncommunicable diseases (NCDs) accounted for 18 of the leading 20 causes of age-standardized YLD on a global scale. Aging of the world’s population is increasing the number of people living with sequelae of diseases and injuries.

The burden of disease methodology was developed by researchers at Harvard and the WHO to quantify the amount of premature mortality and disability present in a population. Disability-adjusted life years includes the number of years lost to ill health, disability (YLD) or years of life lost to premature death (see Fig. 39.12).

Although substantial progress has been made toward reducing mortality and extending life expectancy throughout the world over the past few decades, the epidemiologic transition is manifest in the growing importance of nonfatal diseases, outcomes, and injuries, which pose, partly as a consequence of decreasing death rates, a rising challenge to the ability of the world’s population to live in full health.

For the first time in human history, in 2020, there will be more older persons alive than children (see Fig. 39.13).²¹

In middle-aged adults, musculoskeletal disorders dominated the top rankings followed by mental health disorders, especially depression. Diabetes and sense organ disorders were found to be prominent causes of disability in middle age. In older adults (older than 65 years), sense organ disorders were the top-ranked cause of disability. Musculoskeletal disorders remained a dominant source of disability, and chronic obstructive pulmonary disease entered the top ten. In the oldest age groups, ischemic heart disease and Alzheimer’s and other dementias made their first appearance in the top ten.

According to the recent Lancet Commission report, “These three pandemics—obesity, under-nutrition, and climate change—represent The Global Syndemic that affects most people in every country and region worldwide.”²² They go on, “They constitute a syndemic, or synergy of epidemics, because they co-occur in time and place, interact with each other to produce complex sequelae, and share common underlying societal drivers.” Musculoskeletal pain-related disability and the worldwide sedentarism are similarly part of a syndemic.

Recently, studying masters athletes has given us insight into the nature of aging and its physical effects. Many assume that physical activity can reverse or slow down the aging process, and we confuse the effects of inactivity with the aging process itself, believing certain diseases are purely the result of getting older. In reality, it is not the 80-year-old athlete who has the physiology of the 50-year-old inactive person that is slowing the aging process. They are exactly as they should be. It is the 50-year-old inactive person that is speeding things along.

Steve Harridge, coauthor and professor of physiology at King’s College London, said: “Being sedentary goes against evolution because humans are designed to be physically active.”²³ Evolutionarily speaking, our bodies are designed to be active throughout the entire lifespan. Our modern sedentary lifestyles have essentially sped up age-related decline and contributes to onset of disease such as type 2 diabetes, cardiovascular disease, and cancer. Allowing progression of this plight is that we have been able to rely on “the crutch” of modern medicine to get away with problems related to inactivity.

Endurance cyclists in their 80s have the immune systems of people in their 20s.¹⁴ The elderly endurance cyclists

Duggal et al²⁴ reported that “Aging is accompanied by a decline in immune competence, termed immunesenescence, which is characterized by an increased risk of infections and chronic inflammatory
diseases…. The mechanisms underlying this compromised immunity include involution of the thymus, which begins in early adulthood in humans and accelerates rapidly after 40 years of age.”

Regular physical activity in older adults has been associated with¹⁴

Physical activity is shown to be thymoprotective and preventive of thymic involution, thus helping the immune system adapt to novel pathogens in the environment.¹⁴ Duggal’s group¹⁴ report that “aging is a complex process involving the interaction of a number of factors, including genetics, environment and lifestyle. Our findings highlight that physical inactivity with age may be a profound driver of several aspects of immunesenescence, most notably reduced thymic output, changes to regulatory cell frequency and function and T-cell polarization.” Reduction in thymic output has been suggested as a determinant of mortality in older adults.²⁶

From age group to age group, the average person is not meeting physical activity recommendations: “In England fewer than half of 16-24 year olds meet the recommendation for aerobic and muscle strengthening exercises; for 65-74 year-olds, it falls to fewer than one in 10.” Although this is nothing new, research is not only suggesting that active younger people keep their activity levels up through the aging process, but that 40-year-olds who begin to increase their physical activity levels can also reap similar benefits.²⁷ Physical inactivity is a pandemic affecting people all over the world.²⁸ The Lancet study on Worldwide trends in inactivity reported that, “Insufficient physical activity is a leading risk factor for non-communicable diseases, and has a negative effect on mental health and quality of life.”²⁸ Some key points from the report:

Further research suggests that “maintained physical activity into middle and old age protects against many aspects of immune aging which are in large part lifestyle driven.”²⁴ Along with benefits for the individual, being more physically active has societal benefits as well. “The number of people aged 65 and over is projected to rise by more than 40% in the next 16 years. The average 85-year-old costs the NHS more than five times as much as a 30-year-old, analysis suggests.”³²

These data are becoming more and more pertinent because globally, the population is living longer lives, but not necessarily maintaining quality of health in their later years. “The number of people aged 65 and over is projected to rise by more than 40% in the next 16 years.”³³ “Many benefiting from projected life expectancy increases by 2035 will spend their extra years with four diseases or more, according to a study in England.”

Exercise is the only “medicine” we have to combat some of the biggest factors in loss of physical function because of aging: loss of muscle mass, loss of strength, declining balance, and along with it increased risk for falls. Studies also suggest that resistance training (RT) can benefit

Furthermore, RT not only has physiologic benefits, but also benefits of psychosocial health:

Overprotective advice leads to rigidity (i.e., “safety behaviors” and avoidance), whereas coping is equated with a “flexible” mindset. In this context variability of DST is a fundamental principle for positive coping.⁴⁷

The precision person-centered approach is based on looking at the individual and their environment.^48,49 Psychological and social factors as well as pathology and symptoms are all important. The modern BPS approach is guided by nudging behavior toward higher volumes (Principle 2), intensity (Principle 3), and variability (Principle 4) of activity in order to change beliefs about the relationship of activity and pain or hurt and harm (Principle 1). Changing beliefs (i.e., cognitions) is in a yin-and-yang relationship with changing activity tolerance.

The dichotomy between a biomedical and BPS paradigm is artificial, and as some have suggested, the BPS model still suffers from phenomenologic issues.⁴⁹ The downside of the biomedical approach is that “it inaccurately endorses a linear relationship between noxious stimuli and pain, and is often dualist or reductionist…. From a reductionist perspective, pain is often considered to be ‘in the brain.’”⁴⁹ Similarly, the BPS model is weakened by the fact that the “boundaries between the biological, psychological, and social are artificial, and the model is often applied in a fragmented manner. The model has a limited theoretical foundation, resulting in the perpetuation of dualistic and reductionist beliefs”⁴⁹ (see Fig. 39.14).

Pincus et al reported that the BPS model has been misunderstood and therefore poorly applied. According to Low, “This may be because the bio-psychosocial model fails to explain the body/mind problem, with the biomedical paradigm on one side and the psychological and social perspective on the other with no clear theoretical link between them.”⁵⁰ As described in Chapters 1, 5, and 38, clinicians have compartmentalized patient presentations into bio, psycho, or social rather than taking a person-centered approach as described by Vaz et al.⁴⁸ The greatest oversight is the failure to include the person’s environment as the key milieu within which context gives value to experience of potentially disabling pain.⁴⁸

Worst of all, if imaging is negative or treatments aimed at hypothesized pathologic structures fail to give relief, the HCP mistakenly blames failure to get better on the patient! This is tragic precisely because our ability to be certain that we have accounted for the vast complexity of interacting variables gives us an insurmountable cognitive or confirmation bias.

According to Stilwell and Harman,⁴⁹ an enactivist interpretation appreciates the first-person experience of pain and disability and thus avoids the mereologic fallacies of either

The enactive approach distinguishes itself from both the biomedical and BPS approaches to pain because⁴⁹

Stilwell and Harman⁴⁹ summarize the enactive approach in a thought-provoking relational manner: “… pain does not reside in a mysterious immaterial mind, nor is it an entity to be found in the blood, brain, or other bodily tissues. Instead, pain is a relational and emergent process of sense-making through a lived body that is inseparable from the world that we shape and that shapes us.” This hypothesis leaves much unanswered; however, it should help us to realize that the BPS construct is not a panacea to limitations inherent in a biomedical approach.

Taking a practical approach, what can we measure? Examples of actionable and relatable goals include activity levels, beliefs about the relationship of activity and pain, hurt and harm, and sensitivity versus tolerance. Inactivity is the upstream issue leading to
underpreparation and is intertwined with overprotection. Inactivity is on the rise and related to our modern disability crisis.

We are fighting vested interests, overdiagnosis, the opiate crisis, myths about the inevitability of “wear and tear,” and various other hypes, trends, and urban myths in physiotherapy, rehab, and chiropractic.^3,4,5,54 New weapons such as PMCS and the cognitive-functional training approach are part of a pain revolution, giving people hope, self-efficacy, and a positive experience with movement.^55,56 The challenge is transfer of knowledge from the scientific realm to the practitioner.⁵⁷

LBP is multifactorial, having biologic, psychological, and social components. Yet, seeing these as operating independently is an artificial construct.^49,50,52 Putting this into practice is a challenge.⁵⁸

According to Cholewicki et al,⁵⁹ “To study very complex problems and the effects of specific solutions under various conditions, a ‘system’ approach is advocated whereby the entire system’s behavior is being studied, including the interactions among its elements (in contrast to a reductionist approach whereby a system is broken down into smaller elements, which are then studied in isolation).⁶⁰ Dynamic systems theory has been used to study the impact of various policy interventions to reduce opiate medicine drug abuse for pain management.”⁶¹

A major obstacle in implementing a systems approach to the BPS management of LBP is that knowledge tends to congregate in the individual domains—biomedical or biomechanical, psychological, or social—rather than be integrated.⁵⁹ Attempts to integrate knowledge across several domains of LBP have mostly been limited to qualitative and descriptive models.^62,63,64 Cholewicki et al⁵⁹ “describe the process of identifying and refining the composition and structure of such a model, which constitute the first step in the systems approach…generating individual models (‘mental models’⁶⁵) of participants with diverse expertise in LBP using fuzzy cognitive mapping (FCM)….”^66,67

Functional training should focus on the source of biomechanical overload rather than just where weakness or tightness exists. Too often athletes receive an endless array of exercises to “fix” a problem. For instance, a knee issue will be addressed with various stretching or strengthening exercises but the injury does not respond because the problem was coming from another link in the kinetic chain! If subtalar hyperpronation is the cause of medial collapse of the knee and valgus overload, then no local approach to the knee itself is going to help. Therefore, a functional evaluation should identify the source of biomechanical overload in the kinetic chain before a training plan commences so that the “key link” can be unmasked.

Loss of force transfer at any link of the kinetic chain may lead to “energy leaks,” decreased performance, and resulting injury. Normalizing specific dysfunctions of any movement pattern including the associated joint, muscle, or fascia will likely facilitate improved performance. Mobility deficits of the thoracic spine and hip, and stability deficits of the lateral hip/pelvis and core deserve to be highlighted for their influence throughout the locomotor system.

Identification of painful markers, MSs, painless dysfunctions, signs of abnormal motor control (AMC), and evaluation of training load are important aspects of the assessment process but must be considered within a broader BPS framework. Dr. Lewit acknowledged this in stating “…psychological factors play a great role, as motor patterns are to a certain degree expressions of the state of mind: anxiety, depression and an inability to relax… no less important is the subject’s psychological attitude to pain.”⁶⁸

The “key link” in the patient encounter often extends beyond the kinetic chain to include the patient’s beliefs and mindset. In many cases, the rehabilitation of a painful spine condition may have more to do with reconceptualizing the person’s beliefs about their spine rather than changing tissues related to the spine. Therefore, the art of training involves not only the quality of movement produced by the locomotor system and the load that system is exposed to but also the thoughts, beliefs, and motivations of the human undergoing the training.

An interesting study by Littlewood and Cools⁶⁹ offers a skeptical perspective on the relationship of AMC and painful conditions. “The review reports that 65% (104/160) of those with scapular dyskinesis did not go on to develop shoulder pain, whereas 25% (65/259) of those without scapular dyskinesis did.”

A meta-analysis review reported that scapula-focused approaches for shoulder pain “confers benefit over generalized approaches up to six weeks but this benefit is not apparent by 3 months. Early changes in pain are not clinically significant. With regards to scapula position/movement, the evidence is conflicting.”⁷⁰

A comparison of three factors on shoulder injury rate in elite youth handball players was undertaken⁷¹ (see Fig. 39.15):

An increase in handball load by >60% was associated with greater shoulder injury rate (hazard ratio [HR] 1.91; 95% confidence interval [CI] 1.00 to 3.70, P=0.05) compared with the reference group. The effect of an increase in handball load between 20% and 60% was exacerbated among players with reduced external rotational strength (HR 4.0; 95% CI 1.1 to 15.2, P=0.04) or scapular dyskinesis (HR 4.8; 95% CI 1.3 to 18.3, P=0.02). Reduced external rotational strength exacerbated the effect of an increase above 60% (HR 4.2; 95% CI 1.4 to 12.8, P=0.01). If load increased by less than 20%, there was no increased rate of injury even in those players with scapular dyskinesis or reduced ER strength. They concluded, “A large increase in weekly handball load increases the shoulder injury rate in elite youth handball players; particularly, in the presence of reduced external rotational strength or scapular dyskinesis.”⁷¹

McQuade et al⁷² summarize the prevailing theory regarding scapular stabilization:

McQuade et al⁷² dispute the above idea and state a modern reconceptualization, “it may be more accurate to conceptualize ST function as an energy transfer system rather than an anatomical structural base of support.” The authors continue, “There are several arguments against considering dyskinesia to be an indicator of instability. First, we propose that most observed scapular dyskinesia likely represents normal movement variability.”

The authors conclude, “the current clinical scapular stabilization paradigm is ambiguous, is flawed, and has limited support from current evidence. The notion that there is an ideal scapula orientation or that isolated ST muscle strengthening will be effective for people with dyskinesia is also unsupported.”

Against best practices for the treatment of LBP, typical management today includes excessive imaging and excessive FOCUS ON symptom relief. In both cases, a missed opportunity occurs to educate patients about the positive natural history of LBP and resilience of the human body.

Although the standard of care is slowly improving because of new research regarding the efficacy of mainstream treatment methods, there is still a lot of room for improvement. For clinicians, understanding the mechanism of pain as well as the factors that affect pain is beginning to alter the way LBP is managed. The prognostic significance of psychosocial factors is becoming better understood, yet clinicians are still not addressing these factors directly when managing these cases.

This can be done by

Change has to be a grassroots effort to create a societal shift on LBP management, not just by educating clinicians but by reinforcing those recommendations by changing reimbursement strategies, vested interests, and the financial and professional status quo. Huber and colleagues propose adoption of “Positive Health” as a strategic approach to prevention of long-term disability from LBP. Positive health, Huber says, is “the ability to adapt and to self-manage, in the face of social, physical, and emotional challenges.”

Societally, initiatives are needed to change widespread and inaccurate beliefs about back pain, such as counterproductive patterns of illness behavior, for
example, prolonged rest, avoidance of usual activities, or staying away from work.

In the occupational setting, there needs to be peer support for the notion that LBP is not an injury in need of medical treatment¹⁰⁸ and that the public and patients should adjust expectations so that people are less likely to anticipate a diagnosis or a complete cure for their pain.

Improved training and support of primary care doctors and other professionals engaged in activity and lifestyle facilitation, such as physiotherapists, chiropractors, nurses, and community workers, could minimize the use of unnecessary medical care.

Along with this, system changes integrate and support the health professionals from diverse disciplines and care settings to provide patients with consistent messages about mechanisms, causes, prognosis, and natural history of LBP. Including active strategies such as exercise are associated with reduced disability and less reliance on formal health care.

According to Maher (in Mackee¹⁰⁹), “The contemporary approach relies on a smaller set of red flags than previously and emphasizes the use of clusters of red flags along with clinical expertise to guide decision making.”

It’s important to identify people who have YFs and are at high risk of having persisting problems, as well as people who just need advice to keep moving and how to manage pain themselves. There are several free risk evaluation tools accessible to clinicians to help with this process. These tools include:

O’Keefe and O’Sullivan say, “Overall, people should try to use their back sensibly and build up tolerance to certain activities like bending and lifting through practice with different loads and weights. But people shouldn’t wrap their back in cotton wool and avoid activities. The back, like all body parts, is designed for movement and will adapt to different activities and loads with practice.”¹⁰⁹

It has been theorized that the emergence of modern primates with larger brain sizes has been because of visually guided reaching, grasping, and other forelimb action. Isbell¹¹⁵ postulated that the decisive evolutionary adaptation leading to a larger brain was the emergence of the ability to detect predators—such as snakes—preconsciously and thus to act on those perceptions. This led to the expansion of the visual system and visual cortex and, consequently, increased brain size. Over one-half of the neocortex is associated with vision, thus leading to the much larger brain size of humans.¹¹⁶ According to Huynh Sanh Thong, a MacArthur fellow, snakes were responsible for the origin of language because mothers had to warn their children about them (Thong¹¹⁷ in Isbell¹¹⁵).

According to Isbell,¹¹⁵ neither gesturing in chimps nor bipedalism in hominoids led to language; “it is not clear how bipedalism per se would have operated as a selective pressure favoring language.” It is a social activity and precursor of language.¹¹⁵ Declarative pointing is unique to hominoids whereas chimpanzees utilize gazing, general gesturing, and grunting for social communication.¹¹⁵

The key link from declarative pointing toward having a larger brain is mediated through what we see (and thus the visual cortex). Having increased cortical fear centers in order to assist in predator avoidance also contributed to the expansion of the visual cortex and the development of larger brains in modern primates. “For any given body weight, primates have twice as much brain tissue as most other mammals” (Martin¹²⁰ in Isbell¹¹⁵). Brain tissue is highly metabolically active. Change in brain size has been shown to correlate with the highly metabolic visual pathway neurons such as cytochrome oxidase (CO). CO is “an enzyme complex in the mitochondria that deals with electron transport and is critical for aerobic energy metabolism” (Kadenback¹²¹ in Isbell¹¹⁵).

Isbell suggests that increased dietary glucose (fruits and nectar) helped to develop and enhance our visual processing pathways. Glutamate is the main excitatory neurotransmitter in the central nervous system; however, it can be toxic.¹²³ If there is not enough glucose or CO, glutamate is released presynaptically causing a malfunction in energy metabolism.¹²⁴ Isbell states, “the glucose in fruits protects the K and P pathways from glutamate excitotoxicity.”

Being able to see ripe fruits freed hominoids from dependence on olfaction to find foods and “permitted the metabolic and neurological expansion of primate visual systems.”¹¹⁵ Visual acuity, depth perception, and the ability to discern patterns and shades were not only needed to identify ripe fruits, but also a necessity to stay ahead in the predatorprey arms race by being able to avoid new camouflaged venomous snakes. Primates utilize the visual K pathway for fast preconscious detection of predators. It allows primates to read situations and react in an agile manner based on a threat assessment of visual cues such as if a social engagement is friendly or antagonistic. Isbell argues that “our excellent vision is mainly the result of evolutionary pressure to detect and avoid snakes.”¹¹⁵

Through this divergence of humans and apes, numerous distinguishing structural and functional characteristics are evidenced but few are more relevant than bipedalism, when an organism moves by means of its two rear limbs such as human legs/feet. Although apes and other animals do occasionally stand and walk on two feet, habitual bipedalism, as seen in humans, is rare. Darwin¹²⁵ believed that bipedalism was the spark that set the human lineage off on a separate evolutionary path from the other apes.

“Man could not have attained his present dominant position in the world without the use of his hands, which are so admirably adapted to act in obedience to his will.… But the hands and arms could hardly have become perfect enough to have manufactured weapons, or to have hurled stones and spears with a true aim, as long as they were habitually used for locomotion and for supporting the whole weight of the body, or, as before remarked, so long as they were especially fitted for climbing trees….”¹²⁵

Darwin’s¹²⁵ reasoning for why this form of locomotion was selected (freeing up the hands) has been questioned but it is undeniable that bipedalism set hominids on a very different evolutionary path.

Evolutionary biologist Daniel Lieberman reminds us in The Story of the Human Body that “just as the tough get going when the going gets tough,
natural selection acts most strongly not during times of plenty, but during times of stress and scarcity.”¹¹⁴ It is impossible to know exactly why natural selection favored adaptations for bipedalism, but the majority of evidence points toward a change in climate as the driving force behind the selection of regular upright walking. This adaptation would serve to assist hominids in obtaining food more readily. Between 10 and 5 million years ago, the entire earth’s climate cooled considerably and the overall effect in Africa was to cause rainforests to shrink and woodland habitats to expand.¹²⁶ Those living on the edge of the rainforest would have had to travel farther to obtain adequate food and nutrition.

There are several other popular theories as to why bipedalism was favored in the first hominids, such as to see over tall grass, swim, and improved abilities to make/use tools, but few of these hold up under scrutiny.¹¹⁴

Two advantages of bipedalism are an improved ability to forage and an improved locomotion efficiency. An erect posture would have allowed hominids to reach for hanging fruits by straightening their knees and holding on to a branch.¹²⁷ In this way, standing upright on two feet may have initiated as a postural adaptation. The second advantage of bipedalism is energy conservation. Knuckle walking on all fours is energetically an expensive way to get around. Lab studies have demonstrated that chimps walking on treadmills spend four times more energy compared to humans to cover a given distance.¹²⁸ Lieberman¹¹⁴ states this difference occurs because chimps have short legs, they sway from side to side, and they always walk with bent hips and knees. As a result, chimps constantly spend lots of energy contracting their back, hip, and thigh muscles to keep from toppling over and collapsing to the ground.

Given the fundamental nature of bipedal locomotion to the function of humans, we will examine various morphologic changes that occurred throughout human evolution and that promoted the bodies’ ability to perform this act with great efficiency compared to other species. Again, it is far beyond the scope of this chapter to examine all relevant biologic, environmental, and cultural happenings that helped “shape” human beings. Fossil records show the appearance of five key milestones that occurred during the ape-human bifurcation that are worth discussing¹¹⁴ (see Fig. 39.18):

Structure and function are intimately related. The morphologic changes listed here coincide with functional and capacity changes that allowed for a different output between apes and humans. It is of note that these structural changes and the evolution of habitual bipedalism did not occur overnight and did not require a radical transformation of the body. Although few mammals habitually stand and walk on two legs, the anatomic features that make hominins effective bipeds are actually just modest shifts that were evidently subject to natural selection.¹¹⁴ It is easy to imagine how these adaptations are beneficial (and necessary) in our modern world; however, there was a trade-off for each of these changes in the ancient world. For example, changes in foot and big toe structure may help promote a habitual bipedal gait to cover greater distances searching for food but simultaneously they would make an individual less proficient at climbing to escape predators or access food high in the trees.

The shortened and forward-oriented big toe in the human foot is more suitable for propulsion compared to those of apes and chimps (see Fig. 39.23).¹¹⁴ In addition, the surfaces of the joints between the toes and the rest of the foot in humans are more rounded and point slightly upward, helping us bend our toes at an extreme angle (hyperextend) when we push off.¹¹⁴ This adaptation pairs with the springy arches to allow for a more efficient and effective form of forward locomotion.

As demonstrated in Figures 39.24, 39.25, 39.26, 39.27, this adaptation allows humans to have a more tightly controlled center of gravity (COG) through a combination of big toe extension, ankle mobility, and torso stiffening rather than an inefficient hip flexion strategy.

The modern management of neuromusculoskeletal problems focuses on functional reactivation, restoration, and rehabilitation. Structural problems such as herniated discs or arthritis are relevant in a small percentage of cases and are typically coincidental findings. Therefore, the functional assessment has become a pivotal and often misunderstood component in patient care.

The purpose of functional assessment is to identify a patient’s tolerance, competency, and capacity, as well as functional or performance deficits. This is crucial to create a precision program that bridges the gap from what a patient has (current capacity shortfall) to what they need (required capacity or demands). These functional tests do not replace the initial diagnostic triage of patients, but rather complement it. Acute patients typically receive an evaluation to rule out red flags of serious disease (i.e., tumor, infection, fracture, widespread neurologic loss, or rheumatologic disorder) or nerve root compression. Fortunately, serious disease is present in less than 1% of cases and nerve root compression less than 10% of the time. Evidence-based consensus panel guidelines conclude that in over 80% of LBP patients, the exact pain generator cannot be identified and the label “nonspecific or mechanical back pain” is applied. It is precisely because of this situation that the functional assessment is so important. Patients want to know what is causing their pain, and although a functional diagnosis does not pinpoint causality, it does give the clinician essential targets for reactivation as well as providing simple, inexpensive tests that can be used to audit the patient’s progress toward activity-related goals and recovery.

When a report of examination findings is being given to the patient, it is important to offer a concrete plan of action. This must include measurable landmarks even if specific timelines can’t be given. The major types of care offered should be described and the goals specified. Patients are seeking relief of pain and the modern approach is to reduce threat and AI, increase movement competency and confidence, build strength and robustness, and promote adaptability.

Although the specific “functional” needs of individuals vary, the fundamental patterns and movement literacies performed throughout activities of daily living and across a wide range of populations are, therefore, a logical starting point for movement assessment. Three universal buckets according to Nicole Rodriguez (U.C.L.A. lecture 2018) are

Basic patterns we use every day to train people include squat, single leg bias (e.g., lunge), hinge, push, pull, and locomotion (e.g., carry). However, according to Fred Duncan, these are simply means we use to develop biomotor abilities in hopes of improving movement (personal correspondence). In rehabilitation, we use these BTEs daily but, according to Fred Duncan, “I also understand that I don’t have to. I think truly understanding that is every bit as important as having a plug and play program.” For example, a sprinter may benefit from having a stronger squat, but this is certainly not true for ALL sprinters. Many world record holders are not very skilled in the gym. This is a point that should be borne in mind so that we can avoid confirmation bias in our choices of tests and exercises. As Dr Lewit taught, “Don’t be a slave of methods, the methods should serve the goals.”

Additional characteristic functions to be assessed include:

Choosing the correct functional tests is an art and a science. For acute patients, identifying the movements or positions that reproduce the patient’s characteristic pain—their MS—is essential on an initial visit. This becomes a key audit tool (e.g., posttreatment check) for adjudicating and legitimizing the treatment or exercise prescription, and thus motivating the patient. Once acute pain settles, a more comprehensive functional assessment evaluating AMC or painless dysfunctions can also be performed. The tests chosen will be based on the functional goals or AIs of the patient, in other words, what activities they want or need to do that they are having difficulty performing.

These tests should not be thought of as a SCREEN. The idea that a set of tests can serve as a screen of one’s risk of injury or poor recovery has been debunked (Bahr). Instead, this is merely a list of options for patient evaluation that can be individualized based on a person’s chief complaint, activity level, and goals or demands. It is recommended that only a few of these be selected in any particular case. One will get a lot more information by assessing certain basic exercises like the bird dog, hip hinge, or shin box, so it is preferred to expose and train the BTEs early in patient care.

When instructing assessments, it would be prudent to recall Professor Janda’s advice, “During movement pattern testing, minimal verbal cues should be used which test an individual’s habitual way of performing a movement. If the cues are too ‘leading,’ then the test will be of the subject’s ability to learn how to perform the movement correctly, rather than how they are habitually performing it.”¹³²

For each test, the patient’s MS, scored as a 0, and AMC or painless dysfunction, scored as a 1 or a 2, are noted. Because it is advisable when training patients that good form is ensured, certain signs of faulty movement patterns can be looked for during either movement evaluation or training:

Note: These dysfunctions may also be coincidental findings, be mindful to avoid overdiagnosis, which can be a nocebo.

This section utilizes a consistent format for describing each test: