Muscle Shape & Function.pdf

Muscle Shape & Function Weekday & Weekend Delivery 2024-2025 1 Iain Kemp, PT, MPT, B.Kin Who Am I? Dad, Husband & Human First Physical Therapist (B.Kin., MPT) Educator RockTape C...

Muscle Shape & Function Weekday & Weekend Delivery 2024-2025 1 Iain Kemp, PT, MPT, B.Kin Who Am I? Dad, Husband & Human First Physical Therapist (B.Kin., MPT) Educator RockTape Canada University of Winnipeg Wellington College Various Speaking Events Fringe Canada Clinician Adhartas Physical Therapy Movement Advocate Applied Neurological Lens Advocate for Change 2 Iain Kemp, PT, MPT, B.Kin Who Are You? (Continued…) 1. Educational Background (if any…we all start somewhere) 2. Why Massage Therapy? 3. One thing you’re hoping to learn in NeuroPhysiology Class? 4. If you were stranded on an island… 3 Iain Kemp, PT, MPT, B.Kin  Expectations (Reminder) 1. In Person or Online? You are HERE unless evidence/circumstance otherwise; attendance taken Wonderful to have online, but I won’t be able to attend/tend to, your responsibility to gain the most out of it For WE Delivery Camera’s on unless evidence/circumstance/comfort otherwise; you get out of it what you put into it 2. Office Hours/Meeting/Contact 12pm-2:30pm Tues/Fri; 15 and 30min options, Virtual or In-Person Used for clarifications on concepts, other NP content Questions asked via Teams or Email outside of office hours I can’t guarantee I get to in a timely manner (3-4 days) Everything else is [email protected] 3. Conduct We are all adults, we are all equals, respect Education is all a matter of building bridges Professional demeanour; we’re preparing for the clinical realm Language Respectful and English spoken in class (outside of that you do you) 4 Iain Kemp, PT, MPT, B.Kin  What to Expect (Reminder) 1. Overview of Basic Neurophysiology and importance to massage therapy 30,000ft view Bland, Basic, and a LOT Integration/Application of concepts when able 2. Delivery Combination of lectures, videos, illustrations, workbooks (MC and FIB questions each unit to check understanding - not graded), additional learning info, quizzes (graded), exams (MC and FIB - graded) Some things are presented before a full understanding has been explored; it will all make sense in time I am new, just like you; let’s cut each other some slack I am slowly working on revamping the content for this course; I will get content etc to to ASAP 3. What to study? Lectures slides. That’s it. NOT pictures. NOT videos. If you WANT to learn more, do you I will only examine on what’s in the lecture notes 4. We might be early, we might be late; allotted time is just that Lectures may go by fast or slow; it depends If we’re done early, great! If we’re not, we’ll bleed into the next lecture We may even be done the term early…that means more time for review 5. What Questions do you have? 5 Iain Kemp, PT, MPT, B.Kin Learning Objectives Learning Objectives By the end of this presentation, students will be able to: 1.Identify and describe the different muscle shapes (e.g., parallel, pennate, fusiform) and their functional significance in the human body. 2.Understand the role of muscle tone and differentiate between hypertonicity and hypotonicity, including their neurophysiological mechanisms and clinical relevance. 3.Explain the length-tension relationship and its impact on muscle force production and joint stability. 4.Recognize the concept of muscle plasticity and how muscles adapt to different forms of stress, such as resistance training. 5.Distinguish between the different types of muscle contractions (isometric, concentric, and eccentric) and their functional roles during movement. 6.Apply knowledge of muscle function to clinical massage therapy practices, focusing on improving client outcomes through targeted techniques. 7.Integrate an understanding of proprioception and its relationship to muscle function, supporting balance, coordination, and injury prevention in clients. 6 Iain Kemp, PT, MPT, B.Kin Chapter 1: Muscle Shape & Architecture 7 Iain Kemp, PT, MPT, B.Kin  Muscles Overview Overview ◦ Muscles are fundamental to human movement, posture, and stability. They are highly specialized tissues designed to contract and produce force. ◦ Each muscle's function is closely tied to its structure, with variations in fibre arrangements allowing for different types of movement, force generation, and endurance. ◦ Massage therapists must understand muscle structure to properly assess, treat, and apply therapeutic techniques, helping clients maintain musculoskeletal health. https://www.thermea.ca/massage-therapy/ 8 Iain Kemp, PT, MPT, B.Kin Muscle Shapes Muscle Shapes: An Overview ◦ Muscles are classified into distinct shapes based on the arrangement of their fibres, such as parallel, pennate, fusiform, and circular. These variations affect the muscle's ability to contract, its range of motion, and the type of force it can generate. ◦ The shape of a muscle provides insight into whether it is built for speed, endurance, or strength. For example, longer parallel muscles are better suited for producing fast movements, while shorter, thicker pennate muscles are ideal for generating force. ◦ Understanding these shapes helps massage therapists assess which muscles may be overactive or underactive and apply targeted treatments 9 Iain Kemp, PT, MPT, B.Kin  Muscle Architecture: Parellel Parallel Muscle Architecture ◦ Structure: In parallel muscles, the fibres run lengthwise, parallel to the muscle’s long axis, allowing for a greater range of motion. These muscles typically have long, slender fibres, which enable them to contract quickly but generate less force compared to other muscle architectures. ◦ Function: Parallel muscles are ideal for fast, dynamic movements where flexibility and range are needed. They allow for large excursions but at the cost of less overall power. ◦ Example: Biceps brachii. This muscle, located in the upper arm, is a prime mover in elbow flexion, particularly in quick movements like lifting or pulling. 10 Iain Kemp, PT, MPT, B.Kin Muscle Architecture: Pennate Pennate Muscle Architecture ◦ Structure: In pennate muscles, fibers are arranged obliquely to the muscle’s central tendon, resembling the structure of a feather. This arrangement allows for more fibres to be packed into the muscle, which increases the muscle's capacity for generating force, but reduces its range of motion. These muscles can be uni, bi, or multipennate ◦ Function: Pennate muscles are well-suited for generating strength. Their design allows them to exert a high amount of force, although their movement is more limited compared to parallel muscles. ◦ Example: Rectus femoris, one of the quadriceps muscles, is a bipennate muscle. It plays a key role in extending the knee and flexing the hip, essential movements in activities like running and jumping 11 Iain Kemp, PT, MPT, B.Kin  Muscle Architecture: Multipennate Multipennate Muscles ◦ Structure: Multipennate muscles have multiple rows of fibres running obliquely to several tendons. This increases the number of fibres in the muscle, maximizing force output but limiting range of motion. ◦ Function: Multipennate muscles are highly specialized for generating substantial amounts of force, even though they are less suited for producing extensive movements. ◦ Example: Deltoid, a multipennate muscle, covers the shoulder and plays a crucial role in arm abduction, flexion, and extension. Its architecture enables it to produce the powerful movements required for lifting and throwing 12 Iain Kemp, PT, MPT, B.Kin Muscle Architecture: Fusiform Fusiform Muscles ◦ Structure: Fusiform muscles have a spindle-shaped appearance, being thicker in the middle and tapering toward the ends. The fibres in fusiform muscles run parallel, similar to those in parallel muscles, but their shape allows for a greater focus of force at a specific point. ◦ Function: These muscles are designed for speed and moderate strength, allowing for efficient force transfer along the axis of the muscle. They are not as powerful as pennate muscles but allow for faster and more dynamic movements. ◦ Example: Brachialis, which lies beneath the biceps brachii, plays a critical role in elbow flexion, particularly when the forearm is in a pronated position (palms facing down). 13 Iain Kemp, PT, MPT, B.Kin Muscle Architecture: Circular Circular Muscles ◦ Structure: Circular muscles are arranged in concentric rings around an opening or orifice. These muscles control the opening and closing of passageways in the body, allowing for intake (substances or information), movement or excretion, making them crucial for regulating low of information/substances. ◦ Function: Circular muscles contract to close openings or relax to allow passage. They are critical in bodily functions like swallowing, defecation, and urination, as well as opening and closing of the eyes and mouth. ◦ Example: Orbicularis oris surrounds the mouth and is responsible for actions such as puckering the lips or controlling speech and facial expressions. 14 Iain Kemp, PT, MPT, B.Kin Muscle Architecture: Triangular/Convergent Triangular/Convergent Muscles ◦ Structure: Triangular muscles, also known as convergent muscles, have a broad origin and narrow insertion. This allows the fibres to converge at a single point, providing versatility in movement. ◦ Function: These muscles can generate a moderate amount of force and are capable of pulling in several directions, depending on which fibres are activated. ◦ Example: Pectoralis major, located in the chest, is a powerful muscle responsible for movements such as pushing, throwing, or lifting objects. Its convergent structure allows for a wide range of arm movements. 15 Iain Kemp, PT, MPT, B.Kin Muscle Architecture: Quadrilateral Quadrilateral Muscles ◦ Structure: Quadrilateral muscles are four-sided muscles with fibers running parallel to each other. They are often flat and broad, covering a large surface area, and their uniform structure allows for stability and consistent force generation across the muscle. ◦ Function: These muscles are well-suited for stabilizing joints and providing steady, controlled movements over a broad area. Their design supports uniform force production, making them particularly useful in actions requiring consistent tension. ◦ Example: The pronator quadratus muscle in the forearm is a prime example. It plays a crucial role in pronating (turning) the forearm by pulling the radius over the ulna, especially during rotational movements of the wrist. 16 Iain Kemp, PT, MPT, B.Kin Muscle Architecture: Summary Let’s Play a Game. Which One is Which??? 17 Iain Kemp, PT, MPT, B.Kin Chapter 2: Muscle Tone 18 Iain Kemp, PT, MPT, B.Kin Setting the Tone: Muscle Tone Muscle Tone ◦ Muscle tone is the constant, passive contraction of muscles, which helps maintain posture and readiness for action. It is regulated by a complex interaction between the central nervous system (CNS), peripheral nervous system (PNS), and muscle receptors such as muscle spindles and Golgi tendon organs. ◦ Muscle tone ensures that muscles remain responsive and ready to react to voluntary commands or external stimuli. Variations in tone—such as hypertonicity (excess tone) or hypotonicity (reduced tone)—can affect muscle performance and function. ◦ For massage therapists, understanding muscle tone is critical for evaluating muscular imbalances and applying appropriate techniques to normalize tone. 19 Iain Kemp, PT, MPT, B.Kin Setting the Tone: Muscle Tone Components Governing Muscle Tone Key Components Governing Muscle Tone: 1. Motor Neurons ▪ Motor neurons are nerve cells that originate in the spinal cord and brainstem, transmitting signals to muscles to control contraction and tone. ▪ Alpha motor neurons trigger the contraction of muscle fibers, maintaining basic tone. 2. Muscle Spindles ▪ These sensory receptors are located within muscles and detect changes in muscle length. ▪ They send feedback to the central nervous system (CNS) to help regulate muscle tone by adjusting the level of contraction depending on the muscle's length and stretch. 3. Gamma Motor Neurons ▪ Gamma motor neurons innervate muscle spindles and adjust their sensitivity to stretch, ensuring muscle tone is maintained during changes in muscle length or position. 20 Iain Kemp, PT, MPT, B.Kin Setting the Tone: Muscle Tone Neurophysiological Mechanisms of Muscle Tone Reflex Arcs and Stretch Reflex: ◦ Stretch Reflex is a primary mechanism controlling muscle tone. When a muscle is stretched, muscle spindles detect the change and send signals to the spinal cord. The spinal cord responds by activating alpha motor neurons to contract the muscle, resisting further stretch. ◦ This reflex ensures muscles maintain proper tone, preventing overstretching and maintaining posture. Golgi Tendon Organs (GTOs): ◦ Located in tendons, GTOs detect changes in muscle tension. ◦ They provide inhibitory feedback to motor neurons when tension becomes excessive, protecting muscles from injury by reducing contraction force if needed. Central Nervous System (CNS): ◦ The CNS, including the brain and spinal cord, integrates sensory feedback from muscle spindles and GTOs to regulate overall muscle tone. ◦ Damage to the CNS (e.g., stroke, spinal cord injury) can lead to abnormal muscle tone (e.g., hypertonicity or hypotonicity), affecting posture and movement control. 21 Iain Kemp, PT, MPT, B.Kin Setting the Tone: Muscle Tone https://youtu.be/K2HMZEJMK1E?si=Te2F1vb3t6X8-CnP 22 Iain Kemp, PT, MPT, B.Kin  Setting the Tone: Muscle Tone Brain Pathways Governing Resting Muscle Tone Resting Muscle Tone Regulation: Muscle tone is governed by the complex interaction between the central nervous system (CNS) and peripheral nervous system (PNS). It is primarily regulated by motor neuron activity, which is influenced by higher brain centers, including motor pathways in the brain that send signals to the spinal cord. Brain Pathways Involved in Muscle Tone: 1. Corticospinal Tract皮质脊髓 ▪ Originates in the motor cortex 大脑运动皮层and descends through the brainstem to the spinal cord, where it influences motor neurons. ▪ The corticospinal tract provides voluntary control over muscle tone and fine-tunes motor activity. 2. Extrapyramidal System ▪ Includes motor pathways outside of the corticospinal tract, such as the reticulospinal, vestibulospinal网状脊髓, and rubrospinal tracts红核脊髓. ▪ These pathways influence involuntary muscle tone and postural control by modulating activity in alpha and gamma motor neurons. For example, the reticulospinal tract originates in the reticular formation of the brainstem and helps regulate muscle tone during automatic movements like walking. 3. Basal Ganglia ▪ A group of nuclei deep within the brain 大脑核心that play a key role in regulating muscle tone by influencing movement initiation and muscle stiffness. ▪ Damage to the basal ganglia can lead to disorders such as Parkinson’s disease, which causes rigidity (increased muscle tone) and bradykinesia (slowed movement). 4. Cerebellum ▪ The cerebellum coordinates motor activity and muscle tone by integrating sensory information from muscles and joints. ▪ It adjusts muscle tone to maintain balance and smooth, coordinated movement. Cerebellar damage can lead to hypotonia (decreased muscle tone) and a lack of coordination (ataxia). 23 Iain Kemp, PT, MPT, B.Kin  Setting the Tone: Muscle Tone Dysfunctional Brain Regions Affecting Muscle Tone: 1. Motor Cortex Damage ▪ Lesions or injuries to the motor cortex (e.g., due to stroke or traumatic brain injury) can disrupt corticospinal tract signaling, leading to hypertonia (excessive muscle tone) or spasticity. 2. Basal Ganglia Dysfunction ▪ Parkinson’s disease and other basal ganglia disorders result in abnormal muscle tone regulation. The hallmark feature is rigidity due to impaired inhibitory control over motor output, causing muscles to remain stiff. 3. Spinal Cord Damage ▪ Injury to the spinal cord can disrupt the transmission of signals from the brain to the muscles, leading to spasticity (increased tone) if the damage is above the spinal level controlling muscle reflexes or hypotonicity if peripheral nerve damage occurs. 4. Brainstem Lesions ▪ Damage to the reticular formation in the brainstem can alter the balance of excitatory and inhibitory signals controlling muscle tone, leading to abnormal tone distribution throughout the body. Abnormal Muscle Tone 1. Hypertonicity 2. Hypotonicity 24 Iain Kemp, PT, MPT, B.Kin  Hypertonicity Muscle Hypertonicity ◦ Definition: Hypertonicity refers to increased muscle tone that can result in stiffness, reduced range of motion, and, in extreme cases, spasticity. This condition occurs when there is excessive neural input to the muscles, often due to disruptions in the balance of excitatory and inhibitory signals from the CNS. ◦ Often termed Facilitated; Clients will often report a good or great ability to connect to, contract and “feel” a muscular region moreso, or feel these regions when called upon to use other regions. Client and clinician may say it feels tight, and most often is on movement exam. ◦ Neurophysiological Mechanisms: Hypertonicity is often driven by heightened alpha motor neuron activity or altered gamma motor neuron sensitivity, leading to sustained muscle contractions. Clinically, can also result from impaired inhibition from higher brain centers, or spinal cord lesions. Common conditions like cerebral palsy, stroke, and multiple sclerosis can also cause hypertonicity by impairing inhibitory pathways. ◦ Clinical Implications for Massage Therapy: Massage therapists can help manage hypertonicity through deep tissue massage, myofascial release, and stretching techniques that promote muscle relaxation and reduce neural excitability. 25 Iain Kemp, PT, MPT, B.Kin Hypotonicity Muscle Hypotonicity ◦ Definition: Hypotonicity refers to a reduction in muscle tone, leading to muscle weakness, flaccidity, and diminished resistance to passive movement. This condition is typically seen in individuals with peripheral nerve damage, cerebellar dysfunction, or certain congenital disorders. ◦ Often termed Inhibited; Clients may report a lessened or inability to connect to, contract or “feel” a muscular region when called on to use it. Client and clinician may say it feels tight, despite the fact it may not be on movement exam. ◦ Causes and Mechanisms: Reduced excitability of alpha motor neurons, dysfunction of muscle spindles, or damage to peripheral nerves can all lead to hypotonicity. Cerebellar lesions may also impair the regulation of muscle tone, resulting in weakened motor responses. Common in genetic conditions like Down Syndrome唐氏综合症. ◦ Clinical Implications for Massage Therapy: Massage techniques, such as proprioceptive neuromuscular facilitation (PNF) and gentle joint and peripheral nerve mobilizations, can be beneficial in restoring muscle tone in hypotonic muscles. By improving sensory input to the CNS, massage therapy can assist in reactivating motor pathways and enhancing muscle responsiveness. 26 Iain Kemp, PT, MPT, B.Kin In the Absence of Clinical Drivers “Tightness” tells you NOTHING ◦ In the absence of clinical drivers of dysfunction (cerebellar, basal ganglia, spinal cord, motor cortex, genetic conditon, etc), you can be presented with hyper or hypo-tone that FEELS or the client reports as FEELING “tight” ◦ In time we will be able to develop palpatory skills that aid in our assessment and treatment of undesirable changes in muscle tone ◦ However, simply because something FEELS or is REPORTED to be “tight,” does not always mean it is hypertonic, and thus needs interventions to reduce tone/“tightness” 27 Iain Kemp, PT, MPT, B.Kin  Length-Tension Relationship Length-Tension Relationship ◦ The length-tension relationship refers to the principle that a muscle's force-generating capacity depends on its length at the time of contraction. Maximum force is generated when muscle fibres are at their optimal resting length, allowing for the greatest overlap between actin and myosin filaments. ◦ Muscles that are too stretched or too contracted generate less force, as the actin-myosin cross-bridging becomes inefficient. ◦ Clinical Implications for Massage Therapy: By understanding the length-tension relationship, massage therapists can assess muscle imbalances and apply appropriate techniques to restore optimal length and function. Techniques such as passive stretching or assisted resistance exercises can help re-establish the correct muscle length. 28 Iain Kemp, PT, MPT, B.Kin Who’s got tight hamstrings? Let’s have a little fun, shall we??? ◦ Try to touch your toes in standing; what do you feel? Where? ◦ Try to touch your toes in long sitting ◦ Who was better in sitting? I want you people…the others we’ll get to in time ;) Let’s see if they’re actually tight ◦ Rub your abdomen all over, front to back ◦ Option 1: Diaphragm Stretch w/ Laughing ◦ Option 2: Going cross-eyed w/ x-Body Choo Choo Train ◦ Re-Test your standing toe touch; did anything happen??? Your rules the movement road! 29 Iain Kemp, PT, MPT, B.Kin Chapter 3: Muscle Adaptation 30 Iain Kemp, PT, MPT, B.Kin Muscle Plasticity Muscle Plasticity and Adaptation可塑性和适应性 ◦ Muscles exhibit a high degree of plasticity, adapting to varying levels of stress and mechanical load. Plasticity refers to a muscle's ability to change its structure and function in response to activity, including changes in fiber composition, mitochondrial density, and capillary supply. ◦ Functional Shifts: Chronic mechanical stress, such as that encountered during exercise, can induce a shift in muscle fiber types (e.g., Type IIb fibers becoming more endurance-oriented Type IIa fibers). This allows muscles to better meet the demands placed on them. ◦ Clinical Implications for Massage Therapy: Massage therapy supports muscle adaptation by improving circulation, reducing muscle fatigue, and aiding in the recovery process. Regular massage can enhance muscle recovery following exercise and facilitate long-term muscle adaptations for performance improvements. 31 Iain Kemp, PT, MPT, B.Kin Types of Contractions: Isometric等角等轴 Isometric Muscle Contractions ◦ Definition: During isometric contractions, the muscle produces tension without changing its length. This type of contraction is crucial for stabilizing joints and maintaining posture, especially when the body is in a fixed position. ◦ Example: An isometric contraction occurs when holding a heavy object in place, such as maintaining a steady grip on a dumbbell without moving it. ◦ Clinical Relevance in Massage Therapy: Isometric exercises are often used in rehabilitation settings to strengthen weak muscles without causing strain. In massage therapy, techniques such as post- isometric relaxation (PIR) help release tension and improve flexibility in contracted muscles. 32 Iain Kemp, PT, MPT, B.Kin Types of Contractions: Concentric Concentric同轴Muscle Contractions ◦ Definition: A concentric muscle contraction occurs when the muscle shortens as it contracts. This type of contraction is essential for generating movement, as the muscle pulls on its attachments to produce joint movement. ◦ Example: A concentric contraction happens during the upward phase of a bicep curl, where the biceps brachii shortens to lift the forearm. ◦ Clinical Relevance in Massage Therapy: Understanding concentric contractions is important when evaluating muscle imbalances and overuse. Massage therapists may treat muscles that are overactive due to excessive concentric contractions in daily activities, helping to release tension and prevent repetitive strain injuries. Techniques such as deep tissue massage and myofascial release are commonly used to address these issues. 33 Iain Kemp, PT, MPT, B.Kin  Types of Contractions: Eccentric Eccentric不正圆的 Muscle Contractions ◦ Definition: Eccentric contractions occur when a muscle lengthens while maintaining tension, usually controlling the speed of a movement or resisting an external force. Eccentric contractions are highly effective for muscle control but can also lead to greater muscle damage compared to concentric contractions, especially during high-intensity activities. ◦ Example: The downward phase of a bicep curl, where the biceps brachii lengthens while controlling the lowering of the forearm, is an eccentric contraction. ◦ Clinical Relevance in Massage Therapy: Eccentric muscle activity is associated with delayed onset muscle soreness (DOMS), which massage therapy can help alleviate. By improving blood flow and reducing muscle stiffness, massage therapy aids in recovery from eccentric muscle damage, especially after intense physical exertion. Sports massage techniques are particularly effective in managing eccentric- related muscle soreness and promoting recovery. 34 Iain Kemp, PT, MPT, B.Kin Types of Contractions: Summary https://youtu.be/DkCcn9iBczw?si=fscA0zNDm32Ppday 35 Iain Kemp, PT, MPT, B.Kin  Muscle Hypertrophy, Recovery & Repair Muscle Hypertrophy过度增大 ◦ Definition: Muscle hypertrophy refers to the increase in muscle size as a result of resistance training or other high-intensity physical activities. ◦ Involves both sarcoplasmic hypertrophy (fluid volume) and myofibrillar hypertrophy (increasing the size and number of muscle fibres). ◦ Mechanism: Resistance training causes microtears in muscle fibers, which the body repairs by adding new proteins and increasing fiber size. ◦ Driven by satellite cell activation and enhanced protein synthesis, resulting in larger, stronger muscles. Muscle Recovery and Repair ◦ Definition: A crucial processes that occurs after muscle fibres are damaged during exercise or physical activity. ◦ Involves clearing out metabolic byproducts (such as lactic acid), replenishing energy stores, and repairing damaged tissues through satellite cell activity. ◦ Satellite Cells: Located between the sarcolemma and the ECM ◦ Activated when muscle fibres are injured. They proliferate and differentiate into myoblasts, which then fuse with damaged muscle fibres or form new fibres, leading to muscle repair and hypertrophy. ◦ Clinical Relevance in Massage Therapy: Massage therapy can support hypertrophy and recovery and repair by improving circulation, reducing inflammation, and enhancing the movement of fluids that carry nutrients and remove waste products, thus enhancing the recovery process. Massage also helps reduce muscle tension, allowing for more efficient training and growth. 36 Iain Kemp, PT, MPT, B.Kin Muscle Fatigue Muscle Fatigue ◦ Definition: Muscle fatigue occurs when muscles are unable to maintain the required force of contraction, typically due to prolonged activity, energy depletion, or metabolic buildup. Fatigue can be caused by a combination of metabolic factors, such as the depletion of ATP and glycogen, as well as neural factors, including decreased efficiency in signal transmission from motor neurons. ◦ Metabolic Fatigue: Results from the depletion of energy reserves and the buildup of metabolic byproducts such as lactic acid乳酸, which disrupt normal muscle contraction processes. ◦ Neural Fatigue: Caused by reduced neural input or inefficient signal transmission to the muscles, often seen in prolonged or repetitive activities. ◦ Clinical Relevance in Massage Therapy: Massage therapy helps alleviate muscle fatigue by promoting relaxation, reducing the buildup of metabolic waste, and restoring energy flow to fatigued muscles. Techniques such as rhythmic kneading and stretching help reoxygenate the muscles and reduce the effects of fatigue. For athletes or individuals with high physical demands, regular massage therapy can help prevent fatigue-related injuries and enhance recovery between training sessions. 37 Iain Kemp, PT, MPT, B.Kin Chapter 4: Muscle Coordination 38 Iain Kemp, PT, MPT, B.Kin Agonists & Antagonists Interactions of Skeletal Muscles – Roles of Agonists and Antagonists Agonists (Prime Movers): ◦ An agonist is the primary muscle responsible for generating a specific movement. It contracts to produce the desired action at a joint. ◦ Example: During elbow flexion, the biceps brachii acts as the agonist, contracting to lift the forearm. ◦ Clinical relevance: When a muscle becomes overactive as an agonist (e.g., due to repetitive movements), it may lead to tension and fatigue. Massage therapy can help reduce this tension and restore muscle balance. Antagonists: ◦ An antagonist muscle opposes the action of the agonist. It lengthens as the agonist contracts, allowing smooth movement at the joint. ◦ Example: During elbow flexion, the triceps brachii acts as the antagonist, relaxing and lengthening to allow the arm to bend. ◦ Clinical relevance: Muscle imbalances between agonists and antagonists can lead to dysfunctional movement patterns. Massage therapists can address tightness or weakness in antagonist muscles to improve joint mobility and balance. 39 Iain Kemp, PT, MPT, B.Kin Synergists & Fixators Interactions of Skeletal Muscles – Roles of Synergists and Fixators Synergists: ◦ Synergists are muscles that assist the agonist in performing a movement by adding force or reducing undesirable movement. They ensure coordinated and efficient muscle action. ◦ Example: During elbow flexion, the brachialis works as a synergist to the biceps brachii, helping to lift the forearm. ◦ Clinical relevance: Identifying and treating tight or overactive synergists in massage therapy can enhance functional movement and reduce strain on prime movers. Fixators (Stabilizers): ◦ Fixators stabilize one part of the body while another part moves. They prevent unwanted movement, ensuring that the agonist can perform its action effectively. ◦ Example: During a bicep curl, the rotator cuff muscles act as fixators, stabilizing the shoulder joint so that the biceps can flex the elbow effectively. ◦ Clinical relevance: Massage therapy targeting fixator muscles, especially those prone to overuse (e.g., rotator cuff muscles), can improve joint stability and reduce injury risk. 40 Iain Kemp, PT, MPT, B.Kin  Coordination Coordination of Agonist and Antagonist Muscles ◦ Definition: Agonist muscles are the primary movers in a given action, while antagonist muscles oppose the action of the agonist. Proper coordination between these muscle groups is essential for smooth, controlled movement and joint stability. ◦ Reciprocal Inhibition: When an agonist muscle contracts, the antagonist muscle must relax to allow the movement to occur. This process is regulated by neural feedback loops, ensuring efficient and balanced movement. ◦ Example: During elbow flexion, the biceps brachii (agonist) contracts while the triceps brachii (antagonist) relaxes. ◦ Clinical Relevance in Massage Therapy: Massage therapy can help restore the balance between agonist and antagonist muscles, which is crucial for joint stability and injury prevention. Muscle imbalances between these groups can lead to joint dysfunction, pain, or overuse injuries. Techniques like muscle energy therapy and active release can address imbalances and improve movement efficiency. 41 Iain Kemp, PT, MPT, B.Kin Coordination Muscle Coordination in Complex Movements Movement Patterns: ◦ Complex movements involve coordinated actions between multiple muscle groups and joints. Kinetic Chains动力学链: The concept of kinetic chains highlights how forces are transmitted through the body during activities like walking or lifting. 42 Iain Kemp, PT, MPT, B.Kin  Function in Proprioception Muscle Function in Proprioception ◦ Definition: Proprioception is the body’s ability to sense its position and movement in space, relying on specialized receptors like muscle spindles and Golgi tendon organs. These receptors constantly send feedback to the CNS, helping regulate muscle activity and maintain balance, coordination, and posture. (We’ll learn more about proprioception and the proprioceptive system in the Nervous System section of the course) ◦ Muscle Spindles: Detect changes in muscle length and the rate of lengthening. They provide feedback that helps adjust muscle tension to maintain posture or respond to sudden movements. ◦ Golgi Tendon Organs (GTOs): Monitor tension within tendons and provide feedback that prevents excessive force, protecting muscles from injury. ◦ Clinical Relevance in Massage Therapy: Massage therapy can enhance proprioceptive function by improving the responsiveness of muscle spindles and GTOs. This is particularly important in rehabilitation settings, where restoring proprioceptive awareness is critical for recovering from injuries. Massage can also improve balance and coordination in clients by promoting optimal muscle function and reducing tension in overactive muscles. 43 Iain Kemp, PT, MPT, B.Kin References List of Major References: Archer, P., & Nelson, L. (2013). Applied anatomy & physiology for manual therapists (2nd ed.). Lippincott Williams & Wilkins Biel, A. (2014). Trail guide to the body (6th ed.). Books of Discovery. Ellingson, R. (????). Neuro U1 Manual. Wellington College of Remedial Massage Therapies 44 Iain Kemp, PT, MPT, B.Kin Supplementary Information Chapters: Introduction: Heavy Lifting 00:00 How Muscles Push & Pull 1:13 Functional Muscle Groups: Prime Movers, Antagonists, and Synergists 2:27 Motor Units 3:49 3 Phases of Muscle Twitches: Latent, Contraction, Relaxation 4:41 Graded Muscle Responses 5:22 Temporal Summation vs Tetanus 6:19 Multiple Motor Unit Summation (Recruitment) 7:07 The Size Principle of Recruitment 7:52 Isotonic vs Isometric Movements 8:50 Review 9:28 This video is NOT testable material 45 Iain Kemp, PT, MPT, B.Kin Supplementary Information This video is NOT testable material 46 Iain Kemp, PT, MPT, B.Kin Supplementary Information This video is NOT testable material 47 Iain Kemp, PT, MPT, B.Kin