Kinesiology Prelim Notes PDF

APPLIED ANATOMY & KINESIOLOGY (LEC) ZTV | PRELIM NOTES Topic Outline (Week No.): CARDINAL PLANES 1. Course Orientation Reference position is standard anatomic 2. Kinematics & Kinetics 3. Moveme...

APPLIED ANATOMY & KINESIOLOGY (LEC) ZTV | PRELIM NOTES Topic Outline (Week No.): CARDINAL PLANES 1. Course Orientation Reference position is standard anatomic 2. Kinematics & Kinetics 3. Movement System; Muscle Activity & Strength position 4. Shoulder Complex – Part 1 ○ A standing position with the feet, knees, 5. Shoulder Complex – Part 2 body, and head facing forward and the 6. PRELIM EXAM shoulders rotated so the palms of the hands also face forward with the fingers KINESIOLOGY extended Arranged perpendicular to each other, axis Study of human movement intersecting at the COG Involves an appreciation of the beauty of ○ COG: Slightly anterior to S2 human movement with an understanding of the scientific principles that provide that movement THREE CARDINAL PLANES FRONTAL / CORONAL PLANE PURPOSE ○ Aka Coronal or XY plane To understand movement and the forces ○ Divides the body into front acting on the human body and to learn how and back to manipulate these forces to prevent injury, ○ Z axis restore function and provide optimal human ○ Motions: performance Abduction and adduction (hip, shoulder, digits) FORCES AFFECTING MOTION Ulnar and radial deviation Gravity (abduction/adduction of wrist) Muscle tension Lateral flexion or bending (neck, External resistance trunk) Friction SAGITTAL / MIDSAGITTAL PLANE BIOMECHANICS ○ Midsagittal or YZ plane ○ Divides the body into left and Application of mechanics to the living right human body ○ X axis / ML axis (medial lateral) Statics - Bodies at rest or in uniform motion ○ Motions: Dynamics - Bodies that are accelerating or Flexion/extension (neck, trunk, decelerating elbow and many more) KINEMATICS Dorsiflexion and plantarflexion Deals with types of motion or movement (ankle) without regard for the forces that produce TRANSVERSE / HORIZONTAL PLANE that motion ○ Transverse or XZ plane Divide into two categories: ○ Divides the body into upper and lower ○ Osteokinematics - Movements of the parts bony partners or segments that make up ○ Y axis / vertical axis a joint ○ Motions: ○ Arthrokinematics - Minute movements Medial and lateral rotation occurring within the joint (hip and shoulder) and between the joint surfaces Pronation and supination KINETICS (forearm) Eversion and inversion (foot) Concentrates on the forces that produce or resist the movement  Example: Individual points on the forearm SPECIAL CASES segment move at different velocities, with the Thumb velocity of each point related to its distance from the axis of motion; the farther the Its normal position is rotated 90° from the distance from the axis of motion, the greater plane of the hand the velocity of that point Flexion/extension: frontal plane DEGREES OF FREEDOM Adduction/abduction: sagittal plane The number of planes within which a joint Forearm supination and pronation with the moves elbow in flexion Maximal at three degrees (Shoulder & Hip) UNIAXIAL Motion no longer occurs on a longitudinal Joints that move in one plane around one axis but on an anterior-posterior axis axis Structural type: hinge or pivot Hip medial rotation and lateral rotation with the hip in flexion Flexed hip also rotates on an anterior-posterior axis OSTEOKINEMATICS Describes the movement that occurs between the shafts of two adjacent bones as the two body segments move with regard to each other Motion produced by muscles Examples: Interphalangeal, elbow, & radioulnar/humeroulnar joint TYPES OF MOTION OF OSTEOKINEMATICS Translatory, linear or rectilinear motion BIAXIAL The motion occurs along or parallel to an axis Joints moves around two axes, the All points on the moving object travel the same segments move in two planes distance, in the same direction with the same Structural type: Condyloid, ellipsoidal & velocity and at the same time saddle Example: Elevator moving straight up and down within an elevator shaft Sliding of the carpal bones Curvilinear motion Is another subset of linear motion in which the Examples: MCP/MTP, radiocarpal & CMC joint of object travels in a curved path the thumb Example: When tossing a ball to a friend TRIAXIAL Rotary or Angular motion Movements takes place about three main Occurs in a circle around an axis or a pivot joint axes, all of which pass through the joint’s Every point on the object attached to the axis center of rotation follows the arc of a circle Structural type: ball and socket joint Individual points on the object move at different Examples: Glenohumeral and velocities, and the velocity of each point is acetabulofemoral joint related to its distance from the axis of motion CIRCUMDUCTION  function and mobility An example of a well-coordinated, successive movement combination A motion in which the moving segment follows a circular path Occurs in triaxial joints and is actually a combination of straight plane motions KINEMATIC CHAINS Combination of several joints uniting successive segments JOINT SURFACES The more distal segments can have higher degrees of freedom than do proximal ones Ovoid OPEN KINEMATIC CHAIN (OKC) Radius of curvature varies from point to point Distal segment moves in space The ovoid articular surfaces of two bones ○ Reaching or bringing the hand to mouth forming a joint create a convex-concave paired ○ Kicking a ball relationship Segment motion is not dependent on another Most synovial joints segment, so one segment can either move or not move, regardless of what other segment in Sellar the chain are doing Have both convex-concave surfaces on each Movements are highly variable articulation bone Required for many skilled extremity movements Examples: Stability is sacrificed for mobility ○ CMC of the thumb ○ Sternoclavicular joint CLOSED KINEMATIC CHAIN (CKC) ○ Talocrucal joint Distal segment is fixed & proximal parts move Movement of one segment requires all the segment to move TYPES OF MOTION OF ARTHROKINEMATICS Goal: stability Examples: Chin up Push up Standing from a seated position Half-squat exercise KINEMATIC CHAINS Walking and stair climbing Closed chain position Rolling “rocking” o When we place our weight on the limb Is a rotary or angular motion in which each Open chain activity subsequent point on one surface contacts a o When the limb swings forward new point on the other surface Sliding “gliding” ARTHROKINEMATICS Is a translatory or linear motion in which the Concerned with how the two articulating joint movement of one joint surface is parallel to surfaces actually move on each other Motions the plane of the adjoining joint surface are not voluntary, they are vital for normal joint  One point of reference contacts new points OPEN PACKED POSITION across the adjacent surface Spinning Aka resting position The joint surfaces do not fit perfectly and are A rotatory or angular, motion in which one point of contact on each surface remains in constant incongruent contact with a fixed location on the other ○ Ligamentous and capsular structures surface Most normal joint movement has some are slack combination of rolling, sliding and spinning ○ Joint surfaces may be distracted ACCESSORY MOVEMENTS several millimeters Joint play ○ Allow the necessary motions of spin, Small simultaneous arthrokinematic motions roll and slide typically with an that amount to only a few millimeters of increase in accessory movements translatory motion or full range of motion is not possible and decreased joint friction Essential for normal, pain-free joint function ○ Capsule and ligaments are loosest or Cannot be performed voluntarily by the subject but rather require relaxation of muscle & most slack is the resting position application of passive movement SIGNIFICANCE For evaluation and treatment of joint motion problem In close-packed position, the joint has great mechanical stability with reduced need for CONVEX-CONCAVE RELATIONSHIP muscle forces to maintain the position Convex joint surface moves on the bone with the concavity — the convex joint surfaces move Examples: in the opposite direction to the bone segment ○ In gripping, when the MCP joints are in Concave joint surface moves on the bone with convexity — the concave joint surfaces move in 90° flexion, lateral motion (abduction) the same direction to the bone segment cannot occur CLOSE PACKED POSITION ○ In standing, hips and knees are in their The surfaces of a joint’s segments usually close-packed position match each other perfectly in only one KINETICS position of the joint; point of congruency Deals with forces that produce, stop or modify ○ The maximum area of surface motion of either the body as a whole or the contact occurs individual body segment study of forces acting ○ The attachments of the ligament are on the body farthest apart and under tension ○ Capsular structures are taut MOTION ○ The joint is mechanically The displacement of a body or one of its compressed and difficult to distract segments from one point to another (separate) DETERMINANTS OF MOTIONS Example ○ Elbow joint close pack: full extension Types of motion ○ Translatory or rotary motion Location of motion  ○ Coronal axis, horizontal axis or sagittal displacement axis ○Two dimensions: magnitude and direction Magnitude of motion Displacement - the motion of a body or ○ Distance: How far a force moves a segment that occurs when force is applied body Linear distance - meters or feet TORQUE Rotary distance - degrees Force applied in an arc of motion around an Direction of motion axis ○ Has a positive and a negative component ○ X axis toward the right is positive and toward the left is negative ○ Y axis upward is positive and downward is negative ○ Z axis toward the front or anteriorly is positive and moving backward or posteriorly is negative Rate of motion and change of motion ○ Velocity TYPES OF FORCES (4) Rate at which a body or Gravity segment moves The most prevalent force that all structures Translatory motion encounter meters or feet per Gravitational force - “weight” of an object, body or body segment second (m/s, ft/s, Muscles respectively) Produce forces on their bone segments by Rotatory motion either active contraction or passive stretching degrees per Externally applied resistances second (o/s) Devices and are whatever the muscles must Acceleration ○ Rate at which a change in velocity work against to produce motion occurs ○ Can be either a positive or negative Friction number Resistance to movement between two objects ○ Positive: the segment is moving faster and faster that are in contact with each other Mass ○ Negative: the segment is slowing The amount of matter contained within an down more and more object FORCES Slug Force ○ a push or a pull that produces ○ 1 slug is equal to 14.59 kg  ○ 1 pound is equal to 0.031 slugs friction and air resistance Weight ○ If a ball is kicked on earth it will slowly the force of gravity acting on the object come to halt on the ground as pound/kg friction, air resistance and gravity Moment have acted upon it The result of force acting at a distance from Clinical Situation the point of motion, or the axis ○ Translatory applications can be The product of this distance (d) and the force disastrous when a person is (F): M = d x F transported in a wheelchair, on a Translational forces: d is the length of the stretcher, or in an automobile, and lever arm (or the perpendicular distance the vehicle is stopped suddenly from the force vector to the center of motion) ○ If the person is not attached to the Rotatory forces: the lever arm is the moment vehicle (e.g., by a seat belt), the arm (or the perpendicular distance from the body continues forward until stopped force vector to the joint’s axis of motion) by another force NEWTON’S LAW OF MOTION Newton's First Law of Motion: Inertia If a body Newton's Second Law of Motion: Acceleration is at rest, it will remain at rest, and if a body is in The acceleration (a) of a body is proportionate uniform motion, it will remain in motion, until an to the magnitude of the net forces (F) acting on it and inversely outside force acts upon it Inertia proportionate to the mass (m) of the body -a ○ Property of a body that resists change ∞ F/m in motion or equilibrium A greater force is required to move (or stop Law of equilibrium the motion of) a large mass than a small one ○ When a body is at rest, it is in a state Clinical Situation of static equilibrium (the forces are ○ Two (2) patients with a grade 5/5 in all equal so no motion is occurring) gastrocnemius strength ○ When a body is in a uniform motion, it 1st patient is a 250-lb football is in a state of dynamic player equilibrium because it is moving at 2nd patient is a 100-lb a uniform rate dancer A force is required to start a motion, to ○ Although their strength grades are change direction or speed of a motion, and both normal, you should not expect to stop a motion (ΣF = 0) each of them to lift 250 lb in a heel ○ If a ball is kicked in outer space it will raise exercise continue to move at the same speed as no forces act upon it, such as Newton's Third Law of Motion: Action-Reaction  For every action force there is an equal and moving force to the axis opposite reaction force First-Class Lever Whenever one body applies a force to Seesaw or balance scale another body, that second body provides an Gain either force or distance, depending on equal force in the exact opposite direction the relative lengths of the force arm and the with equal magnitude as the first body; one resistance arm body or object provides the action and the If two forces are equal on either side of a first other provides the reaction force class lever, the force with the longer arm Gravity exerts a force on all objects Forces (distance from the force to the axis) has the on an object are exerted by the things that advantage touch that object Example: Atlanto-occipital joint because the Whenever 2 object contacts, they exert a weight of the head is balanced by neck force on each other extensor muscle force Forces come in pairs Second-Class Lever Example: ○ When a basketball player jumps up for The point of resistance application lies a rebound, he pushes off the ground between the force and the axis so the lever and the ground pushes back at him arm of the resistance is always shorter than the lever arm of the force LEVER Provides a force advantage so large weights A simple machine that consists of a rigid bar can be supported or moved by a smaller that rotates around an axis, or fulcrum force Three (3) elements Example: Wheelbarrow because when a ○ Axis (A) person standing on the balls of the feet ○ Resistance force (R) Third-Class Lever ○ Moving (or holding) force (F) F - Fulcrum/Axis (A); joint The point of force application located between W - Weight/Resistance Force (R); body the resistance and the axis segments Most common in the human body E - Effort/Holding/Moving Force (F); muscle The resistance arm is always longer than the contraction force arm, so the mechanical advantage lies Resistance arm with the resistance force ○ The perpendicular distance from the This arrangement is designed to produce speed axis to the line of action of the of the distal segment and move a small weight resistance a long distance Force arm Occurs in most open-chain motions of the ○ The perpendicular distance from the extremities  ○ Small amount of shortening of a muscle Force Vector Diagrams causes a large arc of motion at the joint Two vector forces are added together when to position the end of the segment in a they are in the same direction large range of positions As in the tug-of-war, when forces occur in the ○ The biceps and brachialis flexing the same direction, their magnitudes are added elbow to bring a cup to the mouth together ○ The anterior tibialis dorsiflexing the Composition of Forces ankle joint to lift the foot off the floor Forces acting at the knee joint when the subject Mechanical Advantage (MA) is sitting with a weight at the ankle Refers to the ratio between the length of the Force Vector Diagrams force arm and the length of the resistance Multiple vector forces that are in different arm directions may still be added together The ratio for a lever system with arm lengths The tail (or start) of one force vector is equal for the force and the resistance is 1 added to the head (or end of the magnitude The ratio for lever systems with a longer and direction) of another force vector until force arm than a resistance arm is greater all of the force vectors are summed together than 1 The ratio for lever systems with a longer Composition of Forces resistance arm than a force arm is less than The weight of the head produces a 1 downward force whereas the traction Force Vectors and their Considerations produces an upward force Forces have magnitude and direction A counterbalance force of 10 lbs from the Vector forces can be combined when more traction unit eliminates the downward force than one force is applied to a body or of the weight of the head, so the actual segment traction force applied to the cervical spine is The combination of these vectors will result in a 15 lbs new vector (resultant vector) Torque Resultant force is the simplest force that results when all of the forces act together Force which is applied around an axis This graphic representation of a tug-of-war Product of force x perpendicular distance from demonstrates that forces occur as a result of its line of action to the axis of motion the magnitude, or amount of pull, each person ○ T=f.d provides and the direction in which each person Expression of the effectiveness of a force in pulls. As long as the total magnitudes are equal turning a lever system in opposite directions, no motion occurs. The greater the distance, the greater the torque, the greater the resistance needed Movement System Resting potential Involves the functional interaction of Under resting conditions when no action is structures that contribute to the act of occurring moving Has a negative value Whatever the muscle activity, it is -60 to -90 mV (average = -85 mV) accomplished through intricate Resting membrane potential: communication between the ○ -70 mV for nerve cell musculoskeletal and nervous systems ○ -90 mV for muscle cell ○ -50 to -60 mV cardiac muscle Nerve cells, muscle cells, and sensory receptors Irritability A neuron innervating a skeletal muscle and the skeletal muscle itself each possess membrane characteristics that allow them to react when a stimulus is provided NERVE & MUSCLE PHYSIOLOGY Depolarization Potential difference Once nervous and muscular tissues react to The imbalance of ions from one side of a a stimulus, the cell's membrane changes its cell membrane to the other resting potential and it becomes more The ions are predominantly (-) inside the positive cell and (+) outside the cell The cell membrane has selective Action Potential permeability The electrochemical messages that are The cell can actively move ions across the propagated through the movement system membrane to main a required resting Propagation of Action Potential potential Repolarization ○ Neural bridge between the upper An active process immediately after and lower motor neurons depolarization that returns the membrane to Afferent system its resting potential ○ Includes all nerves associated with Hyperpolarization the transmission of sensory Inhibitory synapses increase the voltage information into the CNS requirement so it is more difficult to create Efferent system an action potential ○ Includes nerves that regulate Happens for milliseconds only movement and motor behavior Refractory period State in a muscle / cell membrane where it is still difficult to create a depolarization NEUROTRANSMISSION Neurotransmitter Chemicals released by neuron to send “control signals” to other neurons or muscles NERVE FIBERS: AXONAL DIAMETER Synapse Type A Excitatory synapse ○ Largest axons, myelinated ○ causes depolarization of the ○ Type A-alpha, type A-beta, type postsynaptic membrane A-gamma & type A-delta Inhibitory synapse Type B ○ causes hyperpolarization (more ○ Intermediate diameter, myelinated negative potential) of the Type C postsynaptic membrane that tends ○ Smallest diameter, unmyelinated to keep the postsynaptic neuron inactive NERVOUS SYSTEM Upper motor neurons ○ CNS ○ Cerebral cortex and spinal cord Lower motor neurons ○ Ventral horn gray matter of the spinal cord Interneurons Sensory Fibers ○ Within the ventral horn and Fiber origin within the PNS intermediate areas of the spinal cord  Group lA fibers carry impulses from the SKELETAL MUSCLE (in myofilament level) primary sensory receptor in muscles (muscle spindle) Group lB fibers carry impulses from sensory receptors located in tendons [Golgi tendon organs (GTO)] Group II fibers carry impulses from the secondary receptors in the muscle spindle Motor Fibers Sarcomere Fiber origin within the PNS Composition of a myofibril Alpha motor neurons innervate extrafusal Lies between two Z-lines skeletal muscle Inside is myofilaments Gamma motor neurons innervate the Myofilaments intrafusal (within the spindle) muscle fibers are made up of fine threads of two protein molecules ORGANIZATION OF MUSCLE Actin (thin filaments) Myosin (thick filaments) Actin Filament Provides a binding site for the myosin during a muscle contraction 3 main components: actin, troponin, tropomyosin Polymerized to form two-stranded filaments Muscle Fiber that are twisted together Muscle cells; basic structure of a muscle Actin molecules The length varies from a few millimeters to ○ G-actin many millimeters ○ F-actin The diameter of an individual muscle fiber Tropomyosin ranges from 10 to 100 micrometers (um) ○ A rod-shaped molecule and Made up of multiple rod-like myofibrils composed of two separate Myofibrils polypeptide chains that are wound Bundles of filaments within a muscle fiber around each other to form a long Myofilaments rigid insoluble chain Covered by sarcolemma ○ Approximately 40 nm long Composed of sarcoplasm that contains ○ Arranged along the actin filament so mitochondria and SR one tropomyosin is coupled with Sarcoplasmic reticulum covering approx six actin molecules myofibrils  Troponin ○ A regulatory protein that is bound to a specific region of the tropomyosin filament ○ This arrangement provides one troponin globule per 40 nm of tropomyosin filament ○ Has an enormous avidity for calcium ions MUSCLE CONTRACTION & RELAXATION Myosin Filament Relaxed - 2.5μm Consists of polypeptide chains, one pair of Fully contracted - decreased 1.5 μm heavy chains and two pairs of lighter chains, Stretched - increased 13 μm which are coiled together into one large Sarcomere shortening chain ○ 0.5 to 1.0 μm each unit The end of each heavy chain has a globular ○ Biceps brachii - 40,000 sarcomere structure that forms two "heads" of myosin units = 4 cm overall shortening Aka “crossbridges” MUSCLE CONTRACTION Light meromyosin A-bands do not change Heavy meromyosin I-bands become narrower ○ Exhibit enzyme-like qualities splitting H-zone is obliterated ATP → ADP + PO4 + energy Z-lines are pulled closer together so that the I-bands shorten TRANSMISSION OF IMPULSES FROM NERVES TO SKELETAL FIBERS Nerve impulse flow on the motor end plate  AcH on vesicles are freed on myoneural Available from ATP molecules, which are junction or NMJ coupled to myosin crossbridges AcH interact with receptor site Myosin ATPase activity Increase permeability of muscle membrane ○ Myosin acts as a catalyst to split to ions molecules of ATP into adenosine Depolarization of muscle fibers diphosphate (ADP) and inorganic After increase permeability at postjunctional phosphate (Pi) membrane, AcH is inactivated by ○ Stimulated by calcium cholinesterase Sliding Filament Theory Actin and myosin filament slide past at each other during muscle contraction 4 Stages of Sliding Filament Theory CONDUCTION OF MUSCLE IMPULSES TO THE INTERIOR OF THE MUSCLE FIBER Endoplasmic Reticulum Transverse tubular system (T-system) ○ Runs perpendicular to the myofibrils and speeds the transmission of a muscle action potential to all portions of the muscle fiber Sarcoplasmic reticulum (SR) Rest ○ Found deep to the sarcolemma, Cross bridges project from a myosin running parallel and superficial to the filament myofibril ATP is attached near the head of ○ Stores and releases calcium ions crossbridge during the contractile process Troponin covers the active sites on the actin Excitation-Contraction Coupling filament Energy must be supplied to myofilaments to Calcium ions are stored in the sarcoplasmic cause movement of the actin filaments reticulum toward the center of the A-bands Coupling MOTOR UNIT Arrival of muscle action potential All muscle fibers acting as one unit, depolarizes the sarcolemma & transverse contracting or relaxing nearly tubules simultaneously Calcium ions are released and react with Individual motor neuron with its axon & all of troponin the muscle fibers that are innervated by the Change in the shape of the troponin-calcium motor neuron complex uncovers active sites on actin Innervation ratio Crossbridge couples with an adjacent active ○ Used to describe the average site number of muscle fibers per motor Contraction unit in a given muscle Linkage of a crossbridge and an active site All or none law triggers myosin ATPase activity ○ All muscle fibers within a given ATP splits to adenosine diphosphate (ADP) motor unit contract or relax almost + PO4 + energy instantaneously Reaction produces flexion of the GRADATION OF STRENGTH OF MUSCLE crossbridge (powerstroke) CONTRACTION Actin myofilament is pulled a short distance Size principle: the smallest motor units are along the myosin myofilament activated first Z lines are moved closer together Recruitment principle: increasing the Recharging number of motor units activated Crossbridge uncouples from the active site simultaneously increases the overall muscle and retracts tension ATP is replaced on the crossbridge Excitatory input/rate coding principle: Relaxation increasing the frequency of stimulation of Cessation of excitation occurs individual motor units increases the Calcium ions are removed from actin and percentage of time that each active muscle return to Sarcoplasmic reticulum fiber develops maximum tension Troponin return to its shape and covers JOINT RECEPTORS active site Detect joint position and the rate of joint Actin and myosin filament returns to rest movement state Stimulated by the deformation of receptors The degree of response depends on site & magnitude of deforming force GOLGI TENDON ORGAN Lie within muscle tendons near the point of their attachment to the muscle  Detect force or tension in either muscle or ○ Exhibits both phasic and tonic tendinous collagen fibers but not changes in activity muscle length Il afferent fiber Stimulated by tension produced within the ○ Responds primarily to the amount of muscle fibers or the collagenous tendon to stretch which it is attached ○ Purely tonic activity Nerve impulses are transmitted over large, MOTOR FUNCTION rapidly conducting afferent axons (group lb As alpha motor neurons stimulate the fibers) to the spinal cord and cerebellum contraction of extrafusal fibers, gamma Mediate nonreciprocal inhibition, or motor neurons discharge, causing autogenic inhibition contraction of the intrafusal (muscle spindle) ○ Inhibitory input to an agonist muscle fibers and an excitatory message to the The contraction of the intrafusal fibers antagonist muscle adjusts the sensitivity range for changing MUSCLE SPINDLE lengths of the muscle Extrafusal muscle fibers Muscle tone ○ "Regular" or skeletal muscle fibers ○ Postural muscle tone Muscle spindles MUSCLE ACTIVITY & STRENGTH ○ Unique proprioceptors lying within Different types of motions that muscle muscles, parallel to the extrafusal activation produces fibers ○ Isometric Intrafusal muscle fibers (IFMF) ○ Concentric ○ Very specialized muscle fibers lying ○ Eccentric within muscle spindles ○ Isokinetic SENSORY FUNCTION ○ Isotonic Stretch receptor Isometric Send sensory impulses over the la and II Static or holding contractions afferent axons that "inform" other neurons in When a muscle produces force with no the spinal cord and brain of their length apparent change in the joint angle ○ Length of the extrafusal muscle and Stabilization of joints when doing functional of the rate at which a muscle stretch activities occurs Example: planking Abundant in muscles that need to be constantly alerted to even small changes ○ Small muscles of eye, hand, foot la afferent fiber ○ Detects both the amount of stretch and the velocity of the stretch Concentric Isotonic Occurs as the muscle shortens and the Shortening of the muscle and the load on muscle's proximal and distal insertion points the muscle is constant throughout the move closer towards each other excursion Produces acceleration of body segments Seldom, if ever, occur when muscles are Positive work acting through the lever systems of the body Force exerted by the muscle to produce Isokinetic movement of a joint Contraction occurs when the rate of The motion is produced by the muscle movement is constant Isokinetic dynamometer Manual resistance exercise Muscle Anatomic Activity Eccentric Origin - proximal attachments Occurs as the muscle lengthens and the Insertion - distal attachments muscle's points of insertion move away from Action/s in producing specific joint motions each other Proximal attachments often move toward Often occurs against gravity as the muscle fixed distal attachments (closed kinematic controls the speed with which gravity moves chain) the joint Contractions can be concentric, eccentric, Decelerates body segments and provides or isometric shock absorption as when landing from a Movement of the distal segment is often jump or in walking assisted by the force of gravity Negative work Muscles seldom if ever act alone -- they Occurs when an outside force produces more often act with other muscles joint motion while the muscle controls the rate at which that motion occurs Muscle Fibers An external force, often gravity, is Each individual has a combination of these responsible for motion that is done to the fiber types throughout the body. muscle  Some muscles may have more of one fiber A muscle that is the principal muscle type than another and this arrangement producing a motion or maintaining a posture varies from one individual to another Actively contracts to produce a concentric, Although an individual is born with type I eccentric, or isometric contraction and type II fibers, they may change later in Antagonist life according to the individual's activity and A muscle or a muscle group that provides hormone levels the opposite anatomic action of the agonist As we age, muscle fibers also change with During functional activities, it is usually a reduction in the amount of type Il fibers inactive during the activity so it neither Antigravity muscles or postural muscles contributes to nor resists the activity, but its ○ Muscles that work against gravity as passive elongation or shortening allows the we sit or stand desired activity to occur Contain more slow twitch or type I muscle Synergist fibers A muscle that contracts at the same time as ○ Fibers that resist fatigue and are the agonist able to maintain sustained activity Provides identical or nearly identical activity Soleus, peroneals, quadriceps, gluteals, to that of the agonist rectus abdominis, upper extremity Obstructs an unwanted action of the agonist extensors, erector spinae group, and short Stabilizes proximal joints for distal joint cervical flexors movement Mobility muscles or non postural muscles MUSCLE CHARACTERISTICS ○ Muscles that are used for rapid Viscosity movement during explosive activities Resistance to an external force that causes ○ Contain more type II muscle fibers a permanent deformation Fibers that produce force and Elevating temperature reduces viscosity power rapidly but have low ○ Applying heat to tissue before endurance stretching it ○ Gastrocnemius, hamstrings, and Lowering tissue temperature increases the upper extremity flexors tissue's viscosity MUSCLE FUNCTIONAL ACTIVITY Elasticity & Extensibility The relationships of muscles as agonists, Extensibility - the ability to stretch, antagonists, and synergists are not constant elongate or expand They vary with the activity, position of the Elasticity - the ability to succumb to an body, and the direction of the resistance elongating force and then return to normal which the muscle must overcome length when the force is released Agonist The more elasticity a tissue possesses, the Prime mover more extensibility, or temporary elongation, it is able to demonstrate  The more extensibility a tissue has, the less Elastic range / region viscosity it has, and vice versa ○ The tissue is elongated to the point Viscoelasticity at which the slack is taken out of the The ability of the tissue to resist changing its structure so it becomes taut shape when a force is applied to it, but if the ○ If the force or load is released the force is sufficient to cause change, the tissue returns to its normal length tissue is unable to return to its original Plastic range shape ○ Occurs if the force applied continues Very rigid structures are more viscous and to increase less elastic ○ Some of the tissue ruptures because Very pliable structures are more elastic and it is unable to withstand this amount less viscous of stress. STRESS-STRAIN CURVE ○ Permanent change in the tissue's Stress length occurs a force or load that the body or its parts Necking resists ○ If the amount of stress continues to Strain increase past the plastic range the amount of deformation it is able to ○ More and more microscopic ruptures tolerate before it succumbs to the stress occur until the tissue becomes macroscopically damaged ○ The force or load required to create tissue damage is less than previously because the tissue is weakening Failure range ○ If the stress increase continues, immediately before the tissue ruptures entirely, a give in the structure is felt and then the tissue rips apart ○ Continuity of the tissue is lost PARTS OF STRESS-STRAIN CURVE CREEP Toe region The elongation of tissue from the application ○ In a resting state, tissue has a of a low level load over time crimped or wavy appearance ○ When stress is applied to the tissue, this slack is taken up within this region MUSCLE STRENGTH ○ Designed to produce greater State of being strong, the capacity of a shortening distance but less force muscle to produce force, and the ability of a Pennate muscles muscle to generate active tension ○ Attach at oblique angles to a central PARTS OF MUSCLE STRENGTH tendon Muscle's size ○ Shorter than fusiform fascicles Architecture of muscle fibers ○ They produce greater forces to the Passive components of the muscle sacrifice of speed since their total Physiological length of the muscle or length cross section is larger tension relationship of the muscle Passive Components Moment arm length of the muscle Muscle's parallel elastic component Speed of muscle contraction ○ Fascial fibers surrounding a muscle Active tension are parallel to the muscle fibers Age and gender ○ When a muscle elongates beyond Muscle size the point at which its slack is Two parameters: length and width removed, the fascia becomes Parallel muscle fibers passively stretched as the muscle ○ Placed side by side continues to lengthen ○ Muscle's width is greater Muscle's series elastic component ○ Provide greater force ○ Given to the tendon and its fascia Series muscle fibers because of their series arrangement ○ Placed end to end with the muscle: ○ Provide greater speed of motion tendon-muscle-tendon When there are muscles of variable lengths ○ This configuration allows the crossing a joint, the longer muscles provide contracting muscle fibers to transfer that segment's mobility whereas the shorter their forces along the tendon to the muscles provide its stability bone to produce motion In terms of cross section, larger muscles in Length-Tension Relationships normal subjects are stronger than smaller Resting length of a muscle ones ○ A position of the muscle in which Muscle size may increase (hypertrophy) there is no tension within the muscle with exercise ○ The length at which the maximum Muscle size may decrease (atrophy) with number of actin-myosin cross inactivity bridges is available Fiber Architecture ○ Active tension declines as the Fusiform or strap muscles muscle shortens because there are ○ The fascicles are parallel and long fewer cross bridges available throughout the muscle between the actin and myosin fibers  ○ Likewise, as the muscle lengthens, Up to about age 16, the ratio of lean body the actin and myosin fibers move mass to whole body mass is similar in farther apart until crossbridges do males and females not connect between the actin and After puberty, however, the muscle mass of myosin sufficiently to produce males becomes as much as 50% greater tension than that of females, and the ratio of lean Speed of Contraction body mass to whole body mass also The faster a muscle moves through a range becomes greater of motion, the less weight it is able to work Similar in males and females against, or lift ○ Muscle strength per cross-sectional ○ The more rapidly the actin and area of muscle myosin filaments slide past each ○ The proportion of fast-twitch and other, the smaller is the number of slow-twitch muscle fibers in specific links that are formed between the muscles filaments in a unit of time so less FUNCTIONAL EXCURSION OF A MUSCLE force is developed The distance to which the muscle is capable Active Tension of shortening after it has been elongated as Motor units are recruited in an order far as the joint(s) over which it passes according to allows ○ The size of the motor unit (smaller Passive insufficiency ones are recruited first) Occurs when muscles become elongated ○ The size of the muscle cells (smaller over two or more joints simultaneously ones are recruited before larger Full elongation of a muscle prevents further ones) shortening by its opposite muscle ○ The type and speed of conduction of May occur normally or in pathological the muscle fibers (slower type I are conditions recruited before faster type II) Ex: in prone, bent knee (hip flexed, knee Age & Gender extended) = rectus femoris is passive Males are generally stronger than females Ex: in supine, knee flexed = hamstrings In both genders, however, muscle strength increases from birth through adolescence, peaking between the ages of 20 and 30 years, and gradually declining after 30 years of age The greater strength of males appears to be related primarily to the greater muscle mass they develop after puberty Tenodesis soreness does not occur, and the Passive tension of muscles that cross two muscle adapts to the exercise or more joints may produce passive Even greater eccentric forces movements of those joints can be made; there are minimal signs of muscle damage, but if injury occurs, recovery is more rapid Hamstring Strain Sprinting and jumping activities A sudden and sometimes severe injury, Active Insufficiency frequently causing the athlete to fall to the Occurs in multijoint muscles when the ground in agony muscle is at its shortest length & when its In severe injuries, it is a macro-muscle tear ability to produce physiologic force is of a hamstring with hemorrhage into the minimal muscle Ex: in prone, bent knee (hip flexed, knee The tear occurs during the late swing phase extended) = hamstrings and early stance phase of running Ex: in supine, knee flexed = rectus femoris EXERCISE-INDUCED MUSCLE INJURY Delayed-onset muscle soreness (DOMS) Begins about 24 hours after the activity and may continue for up to 10 days post-exercise Other functional signs ○ Decrease in range of motion because of pain ○ Decrease in maximum concentric and eccentric muscle forces of +50% ○ Recovery requires from 5 to 30 days ○ If, after recovery, the eccentric exercise or activity is repeated, it has been found that muscle