KIN 3309 1nd Edition Lecture 4 Outline of Last Lecture I Muscle II Types of Muscle III Characteristics of Muscle IV Function of Muscle V Groups of Muscle VI Muscle Architecture VII Muscle Volume and Cross Section VIII Fiber Organization IX Fiber Organization X Fiber Type XI Individual Muscle Organization XII Sliding Filament Theory XIII Motor Unit XIV Muscle Contraction XV Muscle Twitch and Tetanus XVI Muscle Attachment XVII Characteristics of a Tendon XVIII Mechanical Model of a Muscle These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute XIX Hill Muscle Model XX Torque XXI Muscle Roll versus Angle of Attachment XXII Roll of Muscle XXIII Agonist versus Antagonist XXIV Net Muscle Actions XXV Factors Influencing Muscle Force XXVI Force Velocity Relationship XXVII Force Length Relationship XXVIII Stretch Shortening Cycle XXIX Muscle Fatigue XXX Strengthening Muscle XXXI Principles of Training XXXII Strength Training and Nonathlete XXXIII Training Modalities XXXIV Injury to Skeletal Muscle XXXV Summary XXXVI Quiz Outline of Current Lecture I Organization of the Nervous System II Central Nervous System III Peripheral Nervous System IV Neuron V Motor Neurons VI Structure of a Motor Neuron VII Neuromuscular Junction VIII Motor Unit IX Types of Motor Unit X Motor Unit Properties XI Recruitment XII Reflex XIII Proprioceptive Receptors XIV Muscle Spindle XV Golgi Tendon Organ GTO XVI Joint Sensory Receptors XVII Cutaneous Receptors XVIII Strength Training XIX Flexibility Techniques XX Proprioceptive Neuromuscular Facilitation PNF Stretching XXI Plyometric Training XXII Electromyography EMG XXIII What can be learned from an EMG XXIV EMG Instrumentation XXV Types of EMG XXVI Surface Electrodes XXVII General Concerns XXVIII Characteristics of EMG Signal XXIX Characteristics of Electrical Noise XXX EMG Recording XXXI EMG Analysis XXXII EMG Application XXXIII EMG During Walking XXXIV Summary XXXV Quiz Current Lecture I Organization of the Nervous System a Central nervous system CNS b Peripheral nervous system PNS c Neuron d Motor neurons II Central Nervous System a Where human movement is initiated controlled and monitored b Brain i The center of our thoughts ii The interpreter of our external environment iii The origin of control over body movement c Spinal Cord i The highway for communication between the body and the brain III Peripheral Nervous System a Branching nerves outside of the spinal cord b Connect the CNS to the limbs and organs essentially serving as a communication relay going back and forth between the brain and the extremities IV Neuron a Functional unit of the nervous system V Motor Neurons a Carry signals to the muscle VI Structure of a Motor Neuron a Has a synaptic gap VII Neuromuscular Junction a Motor end plates b Neuromuscular junction c Synapse i Small gap between the terminal branch of neuron and muscle VIII Motor Unit a Groups of motor units often work together to coordinate the contractions of a single muscle b All or non principle c All fibers in a motor unit are of the same type d Type 1 2a 2b IX Types of Motor Unit a Type 1 slow twitch s i Slow contraction times 70 ms ii Generates little tension iii Highly fatigue resistant iv Maintaining posture v Distance runner b Type 2a Fast twitch oxidative FR i Fast contraction times 30 to 50 ms ii More fatigue resistant than type 2b iii Swimming bicycling c Type 2b Fast twitch glycolytic FF i ii iii iv Rapid contraction times 30 to 40 ms Innervated by alpha motor neurons Large neuron to fiber ratios Sprinting jumping weight lifting X Motor Unit Properties XI Recruitment a How to describe the activation of the motor units b Tension generated is determined by the size and number of motor units recruited c Order of motor unit activation i Size principle 1 Type 1 activated first type 2a type 2b d Asynchronous activation i Activation is temporally spaced but summed with preceding motor unit activity ii First one activated first and the next one is activated later its integrated in a special domain e Synchronous activations i Large and small motor units activated together 1 Ballistic movements adaptation from weight training f Frequency coding i Also called rate coding ii High frequency can induce high tension production g Small muscles i All units activated when at 30 to 50 maximum voluntary contraction h Large muscles i Still recruiting units at 100 maximum voluntary contraction XII Reflex a Involuntary neural response to a specific sensory stimulus and is a stereotypical behavior in bother time and space b Types of Reflexes i Myotactic reflex 1 Also called stretch reflex 2 Causes contraction of a muscle being stretched ii Flexor reflex 1 Initiated by painful stimulus 2 Causes quick withdrawal flexion of the limb iii Cutaneous reflex 1 Causes relaxation of muscle with heat or massage iv Propriospinal reflexes 1 Reflexes processed on both sides and at different levels of the spinal cord v Crossed extensor reflex 1 Causes extension of flexed limb when contralateral limb rapidly flexes vi Tonic neck reflex 1 Causes flexion or extension of the limbs when head flexes or extends respectively vii Supraspinal reflexes 1 Reflexes brought into the spinal cord but processed by brain viii Labyrinthine righting reflex 1 Causes body to return head to neutral position when body is tilted or spun XIII Proprioceptive Receptors a Sensory receptors in the musculoskeletal system b Transform mechanical distortion in muscles or joints i Change in joint position muscle length and muscle tension into nerve impulses ii Enter the spinal cord c Muscle spindle d Golgi tendon organ XIV Muscle Spindle a Is found in higher abundance in the belly of the muscle i Lying parallel to the muscle fibers ii Connecting into the fascicles via connective tissue b Monitors muscle stretch c Intrafusal fibers i Are contained within a capsule forming a spindle shape ii Nuclear bag fibers or nuclear chain d Gamma motor neuron i Innervates contractile ends of the muscle spindle e Gamma bias i Readjustment of the muscle spindle length by contracting ends of intrafusal fiber f Gamma loop i Reflex arc that works with stretch reflex ii Includes afferent gamma and alpha pathways g Primary afferent i Type 1a ii Respond to stretch by initiating stretch reflex h Secondary afferent i Type 2 ii Facilitate flexors and inhibit extensor activity i Nuclear bag fiber i Has a large cluster of