Sports Science - Muscular System

• Agonist - Muscle that is contracting
• Antagonist - Muscle that is relaxing or lengthening
• Voluntary muscles: Movement is under the control of the person
• Involuntary muscles: Movement is not controlled by the person
• 3 types of muscles:

  • Skeletal
  • Smooth
  • Cardiac
• Smooth muscles:

  • Fibers are thin and spindle-shaped
  • No striations (stripes)
  • Involuntary
  • Contracts slowly
• Smooth muscles are found in:

  • Circulatory system
  • Lining of the blood vessels
  • Helps in the circulation of the blood
  • Digestive system (Esophagus, stomach, intestine)
  • Controls digestion
  • Respiratory system
  • Controls breathing
  • Urinary system (Urinary bladder)
  • Controls urination
• Found ONLY in the heart
• Contractions of the heart muscles pump blood throughout the body and account for the heartbeat
• Healthy cardiac muscle NEVER fatigues
• Fibers are long and cylindrical
• Fast and slow twitch fibres
• Fast contract forcefully, but fatigue quickly
• Slow contract less forcefully, but fatigue slowly
• Minor functions of muscles:
• Protects the bones and internal organs
• Muscles move bones by pulling not pushing
• Tendons anchor muscle firmly to bones, made of dense fibrous connective tissue
• Any movement is generally accomplished by muscles working in pairs
• Prime Mover (agonist) is the muscle most responsible for the movement
• Antagonist is the muscle or group of muscles that work in opposite to the agonist (usually relaxes)
• Origin: the attachment of the muscle to the bone that remains stationary
• Insertion: the attachment of the muscle to the bone that moves
• Belly: the fleshy part of the muscle between the tendons of origin and/or insertion
• Always work in pairs (agonist and antagonist)
• 2 movements of skeletal muscle:

  • Contraction (shorten) Concentric
  • Extension (lengthen) Eccentric
• Heat production – contraction of muscles produces most of the heat required to maintain body temperature