Characteristics of Slow Twitch Skeletal Muscle (Type I)

  • Needed for Endurance
  • Smaller than fast twitch muscles
  • Take about three times longer to contract after receiving stimulus
  • many mitochondria
  • contain a large amount of myoglobin, which carry oxygen to muscle fibers (similar to hemoglobin, which helps carry oxygen to blood)
  • slow twitch fibers are needed for posture and movement, and in back muscles and muscles of the legs
  • because it needs high levels of blood and oxygen these fibers may receive the most benefit from massage