Neuromuscular System

• Central Nervous System 


  Involves the brain and spine
• Peripheral Nervous System 


  Nerve cells which connect the CNS to the rest of the body
• Automatic Nervous System


  Regulates the function of our internal organs

  Controls some skeletal muscles

  Works involuntarily
• Neuromuscular System 


  Muscles and bones work together to create movement

  Changes in the Neuromuscular system take place before and during exercise

  Prepares body for exercise and begins the cool-down process
• Types of Muscle Fibres

  Type 1 - Slow Oxidative (Slow Twitch)

  Type 2A - Fast Oxidative Glycolytic

  Type 2B - Fast Glycolytic
• Slow Twitch Muscle Fibres (Type 1)

  Slower contraction speeds

  Better adapted to low intensity running

  Produce energy aerobically
• Fast Oxidative Glycolytic (Type 2A)

  Fast contractions speed result in more force and power

  Fatigue occurs quickly

  Used for short and intense bursts of power

  Produce energy anaerobically
• Effects of Fibre Training

  Fibre types are genetically determined

  The size can be increased which is called hypertrophy
• Motor Units 


  A group of muscle fibres and a motor neuron

  Normally only one type of fibre in the units

  The end of each motor unit had a motor junction
• Motor Neuron


  Nerve cells which transmit electrical signals through impulses from the brain to muscles
• Neuromuscular Junction


  Where the motor neuron and muscle fibres meet
• Myofibrils 


  Long filaments which run parallel to each other to form muscle fibres
• Motor Units in Small Muscles

  Fine motor control

  Motor units have few fibres per motor neuron

  Muscle control in the eyes
• Motor Units in Large Muscles

  Gross motor control

  Have a motor unit with a motor neuron feeding hundreds of fibres
• The All or None Law

  Either all muscle fibres contract or none do

  A motor unit physically can't partially contract
• Wave Summation 


  Where a repeated nerve impulse has no time to contract so a sustained contraction occurs rather than twitches

  Calcium build up occurs when the muscle is unable to contract

  Creates greater muscle tension and explosive power
• Tetanic Contractions 


  Occurs after a fast and repeated set of nerve impulses

  Creates a powerful and sustained force contraction
• Spatial Summation 


  The strength of contractions change by altering the number and size of the muscle's motor units

  Impulses are received at the same time which fires off the neuron
• Proprioceptive Neuromuscular Facilitation Stretching (PNF Stretching)

  An advanced stretching technique

  The most effective form of flexibility training that increases range of movement

  Follows the CRAC technique:

  Contract

  Relax

  Antagonist

  Contract
• Muscle Spindles 


  A proprioceptor which is located between skeletal muscle fibres

  Known as Stretch Receptors

  Provide information to the CNS about how far and fast a muscle is being stretched

  Reflex action reduced the chances of injury
• Golgi Tendon Organs 


  Located between the muscle fibre and tendon

  Detects level of tension in muscles

  The muscle contracts isometrically and is able to relax and lengthen

  Known as Autogenic Inhibition
• Features of Slow Oxidative Muscle Fibres (Type 1)

  Slow contraction speeds

  Small motor neurone

  Low force produced

  High mitochondrial density

  High myoglobin density

  High capillary density

  High aerobic capacity

  Low anaerobic capacity