muscular

• Types of muscles

  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• Skeletal muscle

  • Striped / Striated in appearance
  • In the bicep, tricep
  • Voluntary
  • Contracts under Conscious Control
  • Connect to bones via tendons
  • Become fatigued
  • Contract to pull on bones, causing movement
• Cardiac muscle


  • Found in the walls of the heart
  • Involuntary, does not contract under Conscious control
  • Works continuously
  • Does not fatigue
  • Contraction of Cardiac muscle helps force blood through the blood vessels to all parts of the body
  • Each Contraction + relaxation represents One heartbeat
• Smooth muscle


  • Found in the walls of the digestive System
  • Found within blood vessels
  • Involuntary, does not contract under conscious control
  • Regulate digestion
  • Help regulate blood pressure
• Functions of the muscles


  • Deltoid - Abduction of the shoulder
  • Bicep - Flexion of the elbow
  • Tricep - Extension at the elbow
  • Pectoral - Horizontal abduction at the shoulder
  • Wrist flexors - Flexes the hand at the wrist
  • Wrist extensors - Extends/Straightens the hand at the wrist
  • Wrist supinators - Supinates the forearm
  • Wrist pronators - Pronates the forearm
  • Abdominals - Flexion + rotation of the lumbar vertebrae
  • Obliques - Lateral flexion of the waist
  • Quadriceps - Extension at the knee
  • Hip Flexors - Flexion at the hip
  • Hamstrings - Flexion at the knee, extension at the hip
  • Tibialis anterior - Dorsiflexion of the foot
  • Gluteals - Extension, hyperextension
  • Gastrocnemius - Plantar flexion, flexes ankle
  • Soleus - Plantar flexion
  • Erector Spinae - Extension of the spine
  • Trapezius - Elevates and depresses scapula
  • Latissimus dorsi - Extends and adducts lower arm
• Antagonistic muscle pairs


  When a muscle contracts, it pulls on the bone. If a muscle pulls a bone in one direction, another muscle (pair) has to pull to bring the joint back to its original position. Many muscles work in antagonistic pairs, like the bicep and tricep during a curl.
• Agonist


  The muscle that shortens when contracting, responsible for the primary movement
• Antagonist


  The muscle that is responsible for the opposing movement
• Origin


  The stationary end of a muscle
• Insertion


  The end of a muscle that moves
• Examples of antagonistic muscle pairs


  • Bicep + Tricep of the elbow
  • Quadriceps + Hamstrings at the knee
  • Tibialis anterior + Gastrocnemius at the ankle
  • Gluteus + Hip Flexors at the hip
  • Deltoid + Latissimus dorsi at the shoulder
• Synergist


  Muscles that enable the agonist to operate effectively, working with the agonist to control direct movement
• Fixator


  Muscles that stop any unwanted movement throughout the body by stabilising a joint
• Types of Contractions


  • Isometric
  • Isotonic
  • Concentric
  • Eccentric
• Isometric Contractions


  Muscles are contracting but the length does not change, the angle at the joint remains the same, lead to rapid fatigue
• Isotonic Contractions


  There are two sub-sections: Concentric and Eccentric
• Concentric Contractions

  Also known as the upward phase of a movement, the muscle will get shorter and fatter during the contraction
• Concentric Contractions

  • Upward phase of a bicep curl
  • Upward phase of a press up
• Eccentric Contractions

  Also known as the downward phase of a movement, the muscle will get longer and thinner during the contraction, often referred to as the negative phase
• Eccentric Contractions


  • Downward phase of a bicep curl
  • Downward phase of a press up
  • Downward phase of a squat
• Bicep curls


  • Concentric upward phase (Flexion) - Bicep is agonist
  • Eccentric downward phase (Extension) - Bicep is agonist
• Press ups


  • Concentric upward phase (Extension) - Tricep is agonist
  • Eccentric downward phase (Flexion) - Tricep is agonist
• Fibre types


  • Type 1 (Slow twitch)
  • Type 2a (Fast twitch/Post Oxidative)
  • Type 2b (Fast twitch/Fast glycolytic)
• Type 1 (Slow twitch) fibres


  • Contract slowly and with less force
  • Most resistant to fatigue
  • Suited to longer duration, aerobic activities
  • Rich in mitochondria, high capacity for aerobic respiration
• Type 2a (Fast twitch/Post Oxidative) fibres


  • Produce a greater force when contracting
  • More resistant to fatigue than Type 2b
  • Suited to speed, power and strength activities
• Type 2b (Fast twitch/Fast glycolytic) fibres


  • Produce the greatest force when contracting
  • Contract rapidly
  • Least resistant to fatigue (Fatigue fastest)
  • Suited to anaerobic activities, depend upon anaerobic respiration
• All-or-none law


  For a muscle to contract, it must receive motor impulses. If the impulse is not strong enough to activate the motor unit, then none of the muscle fibres contract. This is the all-or-none law of muscle contractions.
• Increased blood supply to the muscular system

  When we exercise, blood vessels expand to draw more blood to the muscles, this is called vasodilation. This provides the muscles with oxygen and glucose, and removes waste products.
• Increased muscle temperature

  As muscles require more energy from fuels, more heat is produced as a by-product. This is the principle of a warm up - increasing temperature increases pliability and range of movement.
• Lactate build-up

  During high intensity exercise, lactate builds up in the muscles, resulting in rapid fatigue. Lactate impedes muscle contractions.
• Micro tears

  Resistance training causes stress on the muscles, resulting in micro tears in the muscle fibres. During rest, these micro tears repair, making the muscles slightly stronger.
• Delayed onset muscle soreness (DOMS)

  Pain felt in the muscles 24-48 hours after exercise, caused by micro tears. DOMS is associated with eccentric contractions.
• Adaptations of the muscular system

  • Muscle hypertrophy
  • Increased tendon strength
  • Increased myoglobin
  • Increased number/size of mitochondria
  • Increased glycogen storage
  • Increased fat storage
  • Increased tolerance to lactate
• Muscle hypertrophy

  When muscles are overloaded, the muscle fibres increase in size, resulting in an increase in the size of the muscle. This allows the muscle to contract with greater force.
• Muscle cramp


  An involuntary contraction of the muscles, often caused by factors like dehydration, inadequate blood supply, or loss of electrolytes.