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Muscle fibre types
 

Muscle fibre types

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    Muscle fibre types Muscle fibre types Presentation Transcript

    • Task
      • Pair up the muscles that work together antagonistically
      • Record in your notes under the title ‘Antagonistic pairs’
    • 3 types of muscular contraction ISOMETRIC CONTRACTION Tension develops in muscle but there is no change in muscle length. It is a static contraction as no movement occurs at the joint ISOTONIC CONTRACTION Tension is produced in the muscles while there is a change in muscle length. It is a dynamic contraction because movement occurs at the joint MUSCULAR CONTRACTION Tension develops in a muscle CONCENTRIC CONTRACTION Tension develops while muscle shortens Causes joint movement ECCENTRIC CONTRACTION Tension develops while muscle lengthens Controls joint movement ISOMETRIC CONTRACTION Stops joint movement
    • Types of contraction Concentric Isometric Eccentric
    • Remember
      • In dynamic movements….
      • Agonist = concentric contraction
      • Antagonist = eccentric contraction
    • Eccentric Contraction
      • The quadriceps muscle group contracts eccentrically as you descend stairs or a hill. The quadriceps contract eccentrically to keep the knee from collapsing too fast or too far.
      • In racquet sports, you are constantly swinging a heavy “weight” — the end of the racquet. That weight would drag your wrist into deep flexion with every swing if not for eccentric contraction of the muscles on the back of the arm.
    • Type of contraction Eccentric contraction of rectus femoris, vastus lateralis, vastus medialis and vastus intermedius
    • Plyometric training Involves movements that produce an eccentric contraction immediately followed by a concentric contraction Plyometrics is used to increase the speed or force of muscular contractions, providing explosiveness for a variety of sport-specific activities. Eccentric contraction occurring in the quadriceps to control the landing position
    • Remember
      • In dynamic movements….
      • Agonist = concentric contraction
      • Antagonist = eccentric contraction
    • Isotonic contraction Eccentric Isometric contraction Concentric
      • Concentric contraction in the biceps brachii during the upward phase of exercise
      • Biceps brachii produces tension and shortens
      • It pulls the forearm upwards to cause flexion of the elbow
      • Eccentric contraction in the biceps brachii during the downward phase of exercise
      • Biceps brachii produces tension and lengthens
      • It slows the lowering of the forearm and controls extension of the elbow
      • Isometric contraction occurs in the biceps brachii when the muscle is holding the weight still
      • Biceps brachii develops tension and stays the same length
      • It stops flexion and extension of the elbow
    • Examples
      • Give a sporting example of each of the following types of contraction
      • Concentric
      • Eccentric
      • Isometric
    • Review Quiz Muscles In silence complete all 10 questions No conferring with others!! All books and notes out of sight!!
    • Grading
      • <4/10 <40% U
      • 4/10 40% E
      • 5/10 50% D
      • 6/10 60% C
      • 7/10 70% B
      • 8/10+ 80%+ A
    • Homework - Movement Analysis Joint Type Type of movement Agonist muscle Antagonist muscle Type of muscle contraction Articulating bones
    • Movement analysis Articulating bones May 2008 Player performing a basketball lay-up shot Use your anatomical and physiological knowledge to complete the table below for the players right knee Joint Joint type Type of movement Agonist Antagonist Type of movement Main muscle fibre type Knee Extension
    • Movement analysis May 2009 Exam – Question 1 [5 marks] Hinge Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius Biceps femoris, Semi-tendinosus, Semi-membranosus Concentric Femur tibia fibula Articulating bones Joint Joint type Type of movement Agonist Antagonist Type of movement Main muscle fibre type Knee Extension
    • Types of exercise
    • Aerobic Exercise
      • Exercise is performed in the presence of oxygen
      • Energy is produced through the process of aerobic respiration
      • Submaximal intensity
      • Occurs over a prolonged period of time
      Glucose + Oxygen Energy Carbon dioxide Water + +
    • Anaerobic Exercise
      • Exercise is performed in the absence of oxygen
      • Energy is produced through the process of anaerobic respiration
      • Maximal intensity exercise
      • Can only be sustained for a short period of time due to build up of lactic acid
      • Build up an oxygen debt
      Glucose Energy Lactic Acid + Oxygen debt - where the demand for oxygen is greater than the supply. After exercise oxygen has to be repaid, which explains why heart rate remains elevated after exercise
    • Usain Bolt How do you become the fastest in the world? Training Muscle size Efficiency of cardiovascular system Efficiency of respiratory system Psychological factors Muscle fibre type
    • Learning objectives
      • To know and understand:
      • The three different fibre types found in the body
      • The characteristics of each type of muscle fibre
      • How the type of muscle fibre affects physical performance in specific activities
      • To be able to:
      • Identify structural and functional characteristics of each muscle fibre type
      • Explain how these characteristics affect the type of activity that performers participate in
    • Skeletal Muscle Fibres
      • Muscle fibre – a long cylindrical muscle cell. Muscle fibres are held together in bundles to make up an individual skeletal muscle
    • Characteristics of Muscle Fibres
      • Excitability – muscles reacting to a stimulus
      • Contractility – muscles contract and apply force
      • Extensibility – the extent to which muscles can stretch
      • Elasticity – muscle returning to their original length
    • Slow twitch (Type 1)
      • Designed for aerobic exercise
      • Use oxygen to produce a small amount of tension over a long period of time
      • Resistant to fatigue
    • Fast twitch (Type 2)
      • Designed for anaerobic exercise
      • Produce a large amount of force in a very short time
      • Fatigue easily
    • Muscle fibre types Marathon 1500m 100m Slow oxidative twitch (SO) Type 1 Fast oxidative glycolytic (FOG)Type 2a Fast glycolytic (FG) Type 2b
    • Type 2a – Fast Oxidative fibres
      • Anaerobic fibres that are more resistant to fatigue than type 2b
      • Generate slightly less force than type 2b muscles
      • Also known as FOG fibres
    • Type 2b – Fast Glycolytic fibres
      • Greatest anaerobic capacity
      • Generate the largest amount of force
      • Also know as FG fibres
    • Structural differences
      • Mitochondria
      A small organelle found in the cytoplasm of muscle cells Convert (metabolise) fuels into energy for use in exercise They are the site of aerobic respiration
    • Structural differences
      • Number of Capillaries
      • Capillaries
        • Very small blood vessels
        • Cell wall only one cell thick which allows oxygen to diffuse through the capillary wall into the muscle cell easily
    • Structural differences
      • Myoglobin content
      • Myoglobin
        • The store for oxygen in the muscle
        • High myoglobin content = lots of oxygen available in the muscle
    • Structural differences
      • Phosphocreatine (PC) stores
      • Phosphocreatine system
        • An energy system used in first few seconds of exercise
        • PC + ADP + enzyme (creatine kinase)
        • =
        • C + ATP (energy)
    • Structural differences
      • Glycogen stores
      During exercise glycogen stored in the muscle is converted to glucose which can be used as an energy source
    • Structural differences
      • Triglyceride stores
      • Triglycerides are fats that can be used for energy
      Consists of 3 fatty acids and a glycerol Used particularly when glycogen stores are low The glycerol is converted to glucose to be used for energy
    • Characteristics
      • Compete the table to show structural characteristics of each of the three fibre types
    • Functional differences
      • Speed of contraction
      • Speed at which the muscles can shortens and generate force
      • Force of contraction
      • The amount of force that is generated during contraction
    • Functional differences
      • Resistance to fatigue
      • How quickly the muscle fatigues and starts to lose effectiveness
      • High resistance to fatigue = muscles can work for long periods of time
      • Low resistance to fatigue = muscles can only work for short periods of time
    • Functional differences
      • Aerobic capacity
      • Ability of muscles to work aerobically (with oxygen)
      • Anaerobic capacity
      • Ability of muscles to work anaerobically (without oxygen)
    • Characteristics
      • Compete the table (handout) to show functional characteristics of each of the three fibre types
    • Can 2b fibres be increased by training?
      • Almost all evidence suggests no
      • Some evidence suggests that can convert but only from fast gycolytic or fast oxidative glycolytic to slow oxidative
    • Muscle fibre percentages
      • Table 1: Fast-twitch muscle percentages compared
      Subject % FG (2b) fibres Sedentary 45-55% Distance runner 25% Middle distance runner 35% Sprinter 84% Cheetah 83%
    • Muscle fibre types
      • People with high % of FG (type 2b) in gastrocnemius would be well suited to speed and strength events
      • e.g. ………….
      • People with high % of SO (type 1) in the gastrocnemius would be well suited to endurance events
      • e.g. ………….
      • If a performer can determine their relative percentages of the 3 muscle fibre types they can choose to take part activities that are suited to their physiological make up.
      • Other factors will also affect their suitability for activities such as training, muscle size and the efficiency of their cardiovascular and respiratory system
    • Warm ups and cool downs
      • To know and understand:
      • The effects of a warm-up and cool-down on skeletal muscles and the affect of specific activity on the skeletal and muscular systems
      • To be able to:
      • Analyse the effect of a warm up and cool-down on skeletal muscle tissue in relation to the quality of performance of physical activity.
    • Exam Question 2009
      • Give two ways that a warm up affects the speed and strength of muscular contraction (2 marks)
      • .......................................................................................................................................................................................................................................................................................................................................................................................................................................................................
    • Warm ups and cool down
      • In pairs
        • Discuss what you need to include in a warm up and a cool down
        • Why?
      • Define warm up and cool down
    • Effects on skeletal muscle Effects of warm up Effects of a cool down
      • Increase in muscle/core body temperature
      • = reduction in muscle viscosity , leading to improvement in the efficiency of muscular contraction
      • = a greater speed and force of contraction due to a higher speed of nerve transmission
      • = an increased elasticity that reduces the risk of injury due to increased extensibility of tendons and ligaments
      • = improved co-ordination between antagonistic pairs
      • Keeps the capillaries dilated, allowing oxygen rich blood to flush through the muscles
      • = an increase in the speed of lactic acid and carbon dioxide removal
      • = reduce acidity level
      • = reduced stimulation of pain receptors
      • Decreased risk of DOMS ( delayed onset of muscle pain and soreness ) experienced 24-48 hours after intense exercise due to microscopic tears in muscle fibres
    • Ice baths
      • The theory
      • Constricts blood vessels
      • Decreased metabolic activity and slow down physiological processes
      • Reduce swelling and tissue breakdown
      • When removed from bath the blood vessels in the legs are flushed with blood rich in oxygen that repays the oxygen debt and flushes away the build up of lactic acid
      Water temperature between12 to 15 degrees Celsius for 5 to 10 minutes
    • Exam Question 2009
      • Give two ways that a warm up affects the speed and strength of muscular contraction (2 marks)
      • .......................................................................................................................................................................................................................................................................................................................................................................................................................................................................
    • Exam Answer 2009
      • Give two ways that a warm up affects the speed and strength of muscular contraction (2 marks)
      • Increased speed/force/strength of muscle contraction
      • Increased speed of nerve transmission to the muscle fibres
      • Increased temperature of the muscle
      • Improved elasticity of muscle fibres
      • Improved co-ordination between antagonistic pairs
      • Reduced muscle viscosity / less resistance in the muscle
    • Homework