Range of Motion Compendium
This article aims to explore the details and relationship between range of motion (ROM) and functional mobility. Range of motion is a prerequisite for human movement and performance. We will begin by looking into the fundamental aspects of ROM and its direct connection to movement possibilities.
Defining Range of Motion and Functional Mobility
Range of motion refers to the entire movement potential of a joint. It encompasses both the joint's angular and the muscle's linear movements. On the other hand, functional mobility is the ability to move purposefully through that range of motion to perform daily activities or sport-specific tasks. The relationship between ROM and functional mobility is directly proportional. As ROM increases, so does the potential for functional mobility. This relationship forms the foundation upon which all human movement is built.
The Primacy of Passive Range of Motion
Passive range of motion is the range through which a joint can be moved without muscular contraction, typically by an external force. This concept is crucial because it sets the boundary conditions of potential movement. Once the boundary conditions are set, the active range of motion operates within the passive range. There is always a gap between the passive and active ranges (+10-15 degrees). The goal is not to create as much passive range as possible but adequate amounts for the desired goal, plus a buffer range. Passive range of motion dictates the movement potential of a joint. Establishing sufficient passive range of motion is the first step in creating optimal movement strategies. If passive range of motion is not present, the body will search for the path of least resistance and find the next best place to move. A lack of passive range of motion creates compensation and poor movement efficiency.
The Length-Tension Relationship: A Biomechanical Imperative
Is there sufficient passive range of motion (PROM) for the task, activity, or goal? PROM is movement possibility. Adequate PROM to a specific task means the tissues involved have a normal length-tension relationship, which implies normal tissue architecture. This indicates that the arrangement of the tissue bioflow allows for normal force transmission and speed of contraction. Normal tissue architecture enables a person to generate maximum force and move quickly at length. The force a muscle can generate depends on its length and shortening velocity, which also depends on its length. Alterations in the length-tension relationship indicate there is suboptimal tissue architecture. Disruptions in the tissue architecture, whether from injury, poor training habits, or insufficient recovery, will affect the length-tension relationship, subsequently affecting the force-length and force-velocity relationships. When a tissue loses the ability to lengthen appropriately, there is always a decrease in the force transmission and the speed at which it can contract. Normal tissue length is the fundamental ingredient for the ability to generate force and create force with velocity.
Length-tension relationship of healthy tissue.
From Passive to Active: The Journey to Functional Mobility
After adequate passive ROM and optimal length-tension relationships are established, the goal must shift to creating active ROM (AROM). AROM is the range through which a joint can move using muscular contraction alone; progressing from passive to active ROM bridges the gap between potential movement and functional mobility. Passive range of motion does not automatically improve how we move. We must be able to control our range of motion and execute force throughout the entire range. All movements have specific prerequisites. Once available (usable) ranges of motion have been established; we need to add movement capacity and increase body control.
The Connective Tissue Conundrum
Connective tissue architecture is often an overlooked component of range of motion. Van der Wal's work (2009) challenges our traditional understanding, emphasizing the dual functional tendencies of connective tissue - "disconnecting" for mobility to create space (room) and "connecting" or binding for functional mechanical interactions. This perspective shifts our focus from isolated anatomical structures to a more integrated view of the musculoskeletal system. The architecture of connective tissue determines mechanosensitive proprioceptors. These receptors respond to the specific types of force exerted on the tissue. Connective tissue contains proprioceptive receptors that are concentrated in areas where they transmit tensile stresses across joints, instead of being neatly categorized as "joint receptors" or "muscle receptors."
BioFlow: A Paradigm Shift
The concept of bioflow changes how we view musculoskeletal organization. It proposes an in-series model for transmitting force through connected body tissues. Nerves branch into muscles, which transition into tendons, ligaments, capsules, and bone—all interconnected by fascia. This bioflow concept challenges us to reconsider how we conceptualize movement and ROM. It is not just about individual muscle actions or joint mobility but about the continuous flow of force through interconnected tissues.
A new paradigm for the architecture of joints (drawing courtesy of Jaap van der Wal). Muscle tissue is red; bones are white; joint capsule and cartilage lining the ends of the bone are blue; fascia, which forms tendons and ligaments, is yellow.
The Neurophysiological Component
The neurophysiological aspects of range of motion (ROM) are just as crucial as the biomechanical factors because the nervous system controls movement through afferent feedback mechanisms. Proprioception, the body's ability to sense its position in space, translates passive ROM into usable ROM, i.e., functional mobility. Understanding and respecting the nervous system's role is essential in optimizing movement potential.
The Joint Capsule: Architect of Movement Potential
The relationship between joint capsule workspace, articular workspace, and global workspace forms the foundation of human movement. Understanding these concepts is crucial for healthcare professionals, particularly chiropractors, physical therapists, and even strength and conditioning specialists, as they directly impact functional mobility and performance.
The hip on the left side of the image shows degnerative changes, while the hip on the right side of the image shows healthy joint space.
Joint Capsule Workspace: The Hidden Determinant
The joint capsule, a fibrous connective tissue structure that envelops synovial joints, plays a more significant role in movement than previously understood. Its workspace, which can be thought of as the 'room' within the capsule where movement can occur, is the primary determinant of a joint's movement potential. This capsular workspace dictates the useable joint workspace, determining the overall movement potential. If a joint has a capsular restriction and cannot rotate, the body technically does not see that articulation as a usable joint. In other words, the capsular workspace is the internal space within the joint capsule that defines the range of motion a joint can achieve. This statement underscores the critical nature of capsular health in joint function. A restricted capsule limits the range of motion and the ability to access and train the surrounding tissues effectively.
Articular Workspace: The Bridge to Function
The articular workspace, directly influenced by the capsular workspace, represents a joint's functional range of motion. Within this space, muscles can generate force and control movement. When capsular restrictions limit the articular workspace, it can lead to compensatory movements, such as shifting the body's weight to other joints or altering the natural movement pattern, and increased stress on other structures, potentially resulting in pain and dysfunction. If the hip joint has a capsular restriction, the body might compensate by shifting more weight onto the knee joint, leading to increased stress on the knee and potential knee pain. Research has shown that improvements in capsular workspace can lead to immediate increases in range of motion and pain reduction.
Global Workspace: The External Expression
The global workspace represents how a joint interacts with the external environment. It manifests both the capsular and articular workspaces in real-world movements. The principle 'you cannot move where you cannot move' means that if a joint lacks the necessary capsular and articular workspace, it cannot perform specific movements or tasks, regardless of muscular strength or coordination. That is to say, no amount of muscle strength or coordination can compensate for a joint's lack of movement potential due to capsular or articular restrictions. This concept has implications for both rehabilitation and performance enhancement. For instance, addressing joint workspace problems may be more effective in treating low back pain than focusing solely on muscular strengthening or flexibility.
Graphic display of the cervical workspace
Practical Applications and Future Directions
Understanding the hierarchy of joint function—from capsular to global workspaces—allows for more targeted and effective interventions. Functional Range Systems, specifically Functional Range Conditioning, prioritize joint capsule health to improve overall movement capacity.
This understanding shifts the focus from traditional static stretching to a more comprehensive approach in clinical practice. We must expand the capsular workspace, improve the connective tissue architecture, and improve the connective tissues' ability to absorb and accept force (i.e., load-bearing capacity). This comprehensive approach addresses joint health at its core. As research in this area continues to evolve, we will likely see a greater emphasis on joint-specific training methodologies prioritizing capsular health. This approach promises to improve how we understand and treat movement dysfunctions, potentially leading to more effective interventions and improved outcomes for patients and athletes.
The Internal Genesis of Movement: From Capsular Workspace to Functional Mobility
The concept that all movement is created and executed internally is fundamental to understanding human biomechanics and performance. This principle aligns seamlessly with our previous discussion on joint capsule workspace and its role in determining movement potential. Let us explore how internal constraints, particularly those related to the joint capsule, form the first barrier to overcome in achieving optimal functional mobility.
The Internal Origin of Movement
Movement begins long before any visible action occurs. It originates in the central nervous system, where motor planning and initiation occur. This internal process involves complex interactions between various brain regions, including the motor cortex, basal ganglia, and cerebellum. The neural signals generated here then travel through the spinal cord to activate specific muscle groups, ultimately resulting in the movement we observe externally. However, the ability to execute these internally generated movement plans heavily depends on the physical constraints within our musculoskeletal system. This is where the concept of joint capsule workspace becomes crucial.
Joint Capsule: The First Internal Constraint
As we have discussed, the joint capsule forms the primary internal constraint on movement. Its workspace directly influences the articular workspace and, consequently, the global workspace of a joint. This hierarchical relationship underscores a critical point: no matter how well-planned or neurologically sound a movement intention may be, it cannot be executed if the joint capsule lacks the necessary mobility. The assertion that "you cannot move where you cannot move" takes on new significance in this context. The joint capsule's condition sets the absolute limits of movement potential, regardless of muscular strength or neural drive.
Overcoming Internal Constraints
Addressing internal constraints, particularly those related to the joint capsule, must be the first step in any movement optimization or rehabilitation program. This priority is supported by research showing that improvements in capsular mobility can lead to immediate increases in range of motion and functional performance. A study published in the Journal of Orthopaedic & Sports Physical Therapy demonstrated that interventions targeting the joint capsule significantly improved shoulder range of motion and function in patients with adhesive capsulitis. This highlights the importance of addressing capsular restrictions before improving muscular strength or motor control.
From Internal Constraints to Functional Mobility
The journey from internal movement creation to functional mobility can be conceptualized as a series of expanding workspaces:
Neural Workspace: Where movement is planned and initiated.
Capsular Workspace: The first physical constraint that must be overcome.
Articular Workspace: The range within which joints can move.
Global Workspace: The ultimate expression of movement in the external environment.
Each of these workspaces is nested within the next, with the capsular workspace acting as the critical bridge between neural intentions and physical capabilities.
Practical Implications
Understanding that all movement is created and executed internally and that internal constraints form the first barrier to overcome has profound implications for movement professionals: The priority must start with evaluating joint capsule workspace before progressing to more complex movement patterns.
Practitioners who focus on these internal aspects of movement more effectively address the root causes of movement limitations rather than merely treating symptoms. The interplay between internal movement creation, execution, and the constraints imposed by joint capsule workspace forms the foundation of human movement possibility. Recognizing and addressing these internal factors is essential for optimizing functional mobility and overall performance. As we deepen our understanding of these relationships, we pave the way for more effective and targeted rehabilitation and performance-enhancement interventions.
External Displays of Movement: The Culmination of Internal Joint Function
The external displays of movement we observe in human performance are, in essence, the visible manifestation of complex internal processes occurring within the joints and surrounding tissues. This relationship between internal joint function and external movement expression is fundamental to understanding human biomechanics. It forms an essential link in the chain from capsular workspace to global movement execution.
Joint workspace is heirarchical in nature. They need to build on each other. If you start with the external display of movement without the proper capsular and articular workspace compensations and possible injury will result.
From Capsular Workspace to External Movement
As we have discussed, the capsular workspace forms the foundation of joint mobility. It directly influences the articular workspace, determining the range of motion available for functional movement. This hierarchical relationship further influences the global workspace - the joint's interaction with the external environment. Ultimately, this cascade culminates in the external displays of movement we observe. A study published in the Journal of Biomechanics (Zhang et al., 2021) demonstrated that restrictions in the hip joint capsule led to measurable alterations in gait patterns. This research provides concrete evidence of how internal joint constraints manifest in observable external movements.
Articular Workspace: The Bridge to External Expression
The articular workspace is a critical intermediary between the capsular constraints and the external expression of movement. It represents the functional range within which muscles can effectively generate force and control movement. When the articular workspace is optimized, it allows for smooth, efficient, and powerful movements. Research in sports biomechanics has shown that improvements in the articular workspace of the shoulder joint correlate firmly with enhanced throwing performance in baseball pitchers (Lee et al., 2020). This underscores the direct relationship between internal joint function and external movement expression.
Global Workspace: The Interface with the External World
The global workspace represents how a joint interacts with its environment, encompassing the physical space around the body and the task demands placed upon it. At this level, we see the full expression of movement potential. A comprehensive review in the Journal of Orthopaedic & Sports Physical Therapy (Brown & Smith, 2022) highlighted how limitations in the global workspace of the knee joint, stemming from capsular and articular restrictions, can lead to compensatory movements in other joints during complex athletic tasks. This illustrates the interconnected nature of joint function and its impact on overall movement patterns.
Exploration of the hip global workspace.
Movement Execution: The Visible Outcome
The external display of movement is the final product of this intricate internal process. It represents the culmination of capsular health, articular freedom, and global joint function. High-level athletic performance, for instance, is a testament to optimizing these internal processes. Consider the fluid movements of a gymnast performing on the uneven bars. The extreme ranges of motion displayed externally are only possible due to the shoulder joints' extensive capsular and articular workspaces. Any restriction in these internal spaces would be immediately apparent in the external expression of the movement.
Practical Implications
Understanding this relationship between internal joint function and external movement expression has significant implications for rehabilitation and performance enhancement:
Assessment protocols should consider the entire chain from capsular workspace to external movement rather than focusing solely on visible outcomes.
Treatment approaches should prioritize optimizing internal joint function to improve external movement quality.
Training programs should incorporate exercises that challenge and expand the capsular and articular workspaces to enhance overall movement potential.
Movement and Space: A Symbiotic Relationship
The relationship between movement and space is fundamental to understanding human biomechanics and functional mobility. This relationship is not unidirectional; instead, it is a complex interplay where movement creates and maintains space while space simultaneously governs movement. Let us explore and tie these concepts back to our previous discussions on capsular, articular, and global workspaces.
Proper workspace gives us more time with our joints, creating a space-time continuum at the joint level.
Movement Creates Space
Movement is not just a consequence of available space; it also creates space within our bodies. This concept is particularly evident when considering the joint capsule and its workspace. We can expand the capsular workspace through regular, varied movement, increasing our potential for movement. For instance, controlled articular rotations (CARs), a technique from Functional Range Conditioning, actively work to expand the capsular workspace. By moving joints through their full range of motion under tension, we create micro-adaptations in the joint capsule, effectively increasing the available space for movement. This process of creating space through movement extends beyond the joint capsule. Regular movement stimulates the production of synovial fluid, which lubricates joints and maintains the health of articular cartilage. This maintenance of joint health further contributes to preserving and expanding movement potential.
Movement Maintains Space
Once space is created, space must be maintained through consistent movement. The principle of "use it or lose it"applies directly here. When we fail to move through our full range of motion regularly, the body adapts by reducing the available space for movement. This concept ties back to our discussion on the articular workspace. The articular workspace, which represents the functional range of motion available to a joint, is directly maintained by regular movement through that range. Without this maintenance, we see a gradual reduction in the articular workspace, leading to decreased functional mobility and increased risk of injury. Research has shown that immobilization can lead to rapid changes in joint capsule properties, including increased stiffness and reduced range of motion. This underscores the critical role of movement in maintaining the spaces we have created within our bodies.
Space Governs Movement
While movement creates and maintains space, it is equally valid that the available space governs our movement capabilities. This concept brings us back to our discussion on the global workspace - how a joint interacts with its environment. The capsular and articular workspaces ultimately limit the global workspace. No matter how strong or coordinated an individual may be, they cannot move beyond the limits set by their joint capsules and articular surfaces. This principle is encapsulated in the earlier phrase: "You cannot move where you cannot move." This movement governance by available space has profound implications for rehabilitation and performance enhancement. It suggests that before focusing on strength or skill acquisition, we must ensure that the necessary space for movement exists within the body.
Tying It All Together
The concepts we have explored throughout this article - from capsular workspace to global workspace, from internal movement creation to external expression - converge in this understanding of the relationship between movement and space.
The capsular workspace sets the foundation for all movement potential. Through movement, we can expand this workspace, increasing our articular workspace. This expanded articular workspace allows for greater freedom of movement within the global workspace, enabling more efficient and effective interaction with our environment.
However, the individual must maintain the expanded space through regular, varied movement. Failure to do so can reduce available space, limit our movement potential, and potentially lead to dysfunction or injury.
Understanding this cyclical relationship between movement and space allows for more targeted and effective rehabilitation and performance enhancement approaches. It emphasizes the importance of not only strengthening muscles or practicing skills but also actively working to create and maintain the space necessary for optimal movement.
Summary: Movement and space exist in a symbiotic relationship, each influencing and being influenced by the other. By recognizing and leveraging this relationship, we can develop more comprehensive and effective strategies for improving human movement and function.
