Kinesiology Muscles MOV 300
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This 39 page Class Notes was uploaded by Maria D'Angelo on Monday February 22, 2016. The Class Notes belongs to MOV 300 at Grand Valley State University taught by Dr. Krisanne Chapin in Winter 2016. Since its upload, it has received 22 views. For similar materials see Kinesiology in Cinema And Media Studies at Grand Valley State University.
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Date Created: 02/22/16
Skeletal Muscles Responsible for movement of body and all of its joints – ac▯ve force genera▯on • Protec▯on & dynamic stability of joints • Posture & support • Produce a major por▯on of total body heat Skeletal Muscles 600+ skeletal muscles = ~40 to 50% of body weight 215 pairs of skeletal muscles work in coopera▯on with each other to perform opposite ac▯ons at the same joint Aggregate muscle ac▯on muscles work in groups rather than independently to achieve a given joint mo▯on Shape of Muscles & Fiber Arrangement Parallel muscles ﬁbers arranged parallel to length of muscle produce a greater range of movement than similar sized muscles with pennate arrangement Flat, fusiform, strap, and radiate Fiber Arrangement -‐ Parallel Flat muscles Usually thin & broad, origina▯ng from broad, ﬁbrous, sheet-‐like aponeuroses (a▯achment to bone) Muscle forces spread over a broad area Fusiform muscles Spindle-‐shaped with a central belly that tapers to tendons on each end Allows them to focus their power onto small, bony targets Fiber Arrangement -‐ Parallel Strap muscles More uniform, essen▯ally all ﬁbers arranged in a long parallel manner Enables a focusing of power onto small, bony targets Radiate muscles Also called: triangular, fan-‐shaped or convergent Have combined arrangement of ﬂat & fusiform Fiber Arrangement -‐ Pennate Pennate muscles Shorter ﬁbers arranged obliquely to their tendons Arrangement increases the cross sec▯onal area of the muscle, thereby increasing the power Fiber Arrangement -‐ Pennate Unipennate muscles Fibers run obliquely from a tendon on one side Bipennate muscle Fibers run obliquely on both sides from a central tendon Mul▯pennate muscles diagonally between them h ﬁbers running Muscle T erminology Origin-‐ most proximal and medial a▯achment point, moves the least Inser▯on-‐ more distal, moves the most Ac▯on-‐ ex. Flexion/ extension etc.. Muscle T erminology: Types of Contrac▯ons Isometric-‐ equal Isotonic – ac▯ve muscle force/ tension to either cause or control joint movement • Concentric – posi▯ve contrac▯on, going against gravity • Eccentric-‐ lengthening contrac▯on (muscle ge▯ng longer), going with gravity, nega▯ve contrac▯on Muscle T erminology: Roles of Muscles Agonist-‐ does the mo▯on, prime mover Antagonist-‐ opposing, some▯mes relaxed Stabilizer -‐ maintaining posi▯on, ac▯ve Neutralizer-‐ keep neutral posi▯on Role of Muscles Force Couples Two or more forces pulling in diﬀerent direc▯ons on an object, causing the object to rotate about its axis Coupling of muscular forces together in the body can result in a more eﬃcient movement Types of contrac▯on Keep in mind…. Movement may occur at any given joint without any muscle contrac▯on whatsoever • referred to as passive and due to external forces • applied by another person, object, or resistance • or the force of gravity in the presence of muscle relaxa▯on Determina▯on of Muscle Ac▯on Palpa▯on-‐ using hands Electromyography-‐ electrical ac▯vity in muscles (using electrodes) Electrical s▯mula▯on-‐ provide external s▯mula▯on to see contrac▯on Anatomical lines of pull Determina▯on of ac▯on: Lines of Pull Loca▯ons of origin and inser▯on Planes of mo▯on through which joint can move Muscle’s rela▯onship rela▯ve to the joint’s axes of rota▯on Force Produc▯on Factors: Fiber type Size of the motor unit Size of the neural signal Increases the number of motor units recruited AND their ﬁring rate Fiber Type Type I – Slow twitch (ST). Resist fa▯gue , but less force. (good for endurance) More sensi▯ve to ac▯va▯on s▯muli Recruited ﬁrst, low threshold for neural signal Type II (a & b) – Fast twitch (FT). Greater shortening velocity, so greater force. Fa▯gue quickly. (sprinter) Greater s▯mulus required to ac▯vate, less sensi▯ve threshold later, when neural signal exceeds higher Motor Unit-‐ motor unit and the ﬁbers it innovates (either slow or fast not both) Motor Unit Func▯on as a single unit – this is the All or none principle motor unit will either ﬁre and contract maximally, or not at all Motor Unit The number of motor units responding will depend… Less than 10 in muscles requiring precise and detailed control A few thousand in large muscles that perform less complex ac▯vi▯es Eyes-‐ few motor units for precision Running or jumping-‐ a lot of motor units for force Force Produc▯on To increase force produc▯on ac▯va▯ng those motor units containing a greater number of muscle ﬁbers ac▯va▯ng more motor units increasing the frequency of motor unit ac▯va▯on Motor Unit Ac▯va▯on s▯mulus (ACTION POTENTIAL) is applied trical Motor Unit Ac▯va▯on Motor Unit Ac▯va▯on Greater contrac▯on forces may also be achieved by increasing the frequency of motor unit ac▯va▯on Length-‐T ension Rela▯onship Maximal ability of a muscle to develop tension/force varies depending upon the length of the muscle during contrac▯on Extensibility-‐ muscles beyond res▯ng length Elas▯city-‐ tension due to muscle wan▯ng to go back to res▯ng length Length-‐T ension At 50-‐ 60 % of res▯ng length ability to develop contrac▯le tension is essen▯ally reduced to zero Greatest amount of ac▯ve tension when a muscle is stretched between 100-‐ 130% of its res▯ng length Stretch beyond 100% to 130% of res▯ng length signiﬁcantly decreases the amount of force muscle can exert Length-‐T ension Not as much ver▯calMost ver▯cal heigNot as much ver▯cal height Length-‐T ension More weight max bc slack at knee Force – Velocity Rela▯onship Force-‐Velocity Rela▯onship Concentric – Inverse rela▯onship • As force needed to cause movement of an object increases the velocity of concentric contrac▯on decreases • Force goes up leads to contrac▯on speed goes down Eccentric – propor▯onal rela▯onship • As force needed to control an object’s movement increases, the velocity of eccentric lengthening increases, at least un▯l control is lost • Force up leads to lengthening speed up Stretch-‐shortening Cycle Sequencing & ▯ming of contrac▯ons can enhance the total amount of force produced An eccentric stretch on the muscle prior to the desired concentric contrac▯on • Elas▯c energy is stored, muscle spindle ac▯vated HOWEVER, to get the beneﬁt, the transi▯on between eccentric and concentric must be immediate Uniar▯cular muscles Cross & act directly only on the joint that they cross one joint Ex. Brachialis Can only pull humerus & ulna closer together Biar▯cular muscles Cross and act on two diﬀerent joints Depending, biar▯cular muscles may contract and cause mo▯on at either one or both of its joints Advantage Are able to maintain a rela▯vely constant length Biar▯cular muscles Example: Squat If only knee extension occurs: rectus femoris shortens & decreases in its ability to exert force With hip extension: rela▯ve length & force produc▯on the hip joint during extension Biar▯cular muscles Ex. 2 Hip & knee biar▯cular muscles Countercurrent movement pa▯ern occurs in kicking During the lower extremity forward movement phase the rectus femoris concentrically contracts to ﬂex the hip & extend the knee These two movements, when combined, increase the tension or stretch on the hamstring muscles both at the knee & hip Mul▯ar▯cular muscles Mul▯ar▯cular muscles act on three or more joints due to the line of pull between their origin & inser▯on crossing mul▯ple joints Principles rela▯ve to biar▯cular muscles apply similarly to mul▯ar▯cular muscles Ac▯ve & Passive Insuﬃciency Ac▯ve insuﬃciency can not generate or maintain ac▯ve tension int that it Passive insuﬃciency when the opposing muscle becomes stretched to the point where it can no longer lengthen & allow movement Ac▯ve Insuﬃciency When full range of mo▯on is a▯empted in all joints cross by the muscle Passive Insuﬃciency Hamstrings can not usually stretch enough to allow both maximal hip ﬂexion & maximal knee extension Virtually impossible to ac▯vely extend the knee fully when beginning with the hip fully ﬂexed or vice versa Unit 2 TUESDAY Bones Composi▯on and anatomy Strength-‐ calcium carbonate calcium phosphate and water Flexibility-‐ collagen Muscles Growth & development Tissue proper▯es Wolﬀ’s Law-‐ bones grow according to the Types of contrac▯ons forces applied to it Muscle ac▯ons and roles of muscle Reciprocal Inhibi▯on Loading tolerance, stress-‐strain curve Osteoporosis, female athlete triad-‐ Motor Units: All or None Principle osteoporosis, ea▯ng disorder, amenorrhea Factors aﬀec▯ng force produc▯on Joints Length-‐Tension Rela▯onship Force-‐Velocity Sta▯c stability-‐ ligaments, car▯lage, fascia, bone Stretch-‐Shortening Cycle Classiﬁca▯on/types Ac▯ve & Passive insuﬃciency Mo▯ons allowed at synovial/diarthrodial Factors aﬀec▯ng joint stability Eccentric-‐ being controlled So▯ ▯ssue structures Concentric-‐ controlling Improving mobility – stretching GTOs and MS PNF – Propriocep▯ve Neuromuscular Facilita▯on
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