Post by ef1 on May 9, 2006 9:49:32 GMT
What are slow twitch and fast twitch muscles?
There are actually three types of muscle fibers found in the human body: slow twitch, fast twitch A, and fast twitch B. Slow twitch muscle fibers are used primarily in aerobic activity. These longer muscle fibers are highly resistant to fatigue, but they have a slower contraction time than fast twitch muscles. Endurance athletes, such as distance runners, have a high percentage of slow twitch muscle fibers in the body. Furthermore, the activities of daily life, most importantly, maintaining correct posture, are run by these slow twitch or long muscle fibers.
Meanwhile, fast twitch muscle fibers have a quick contraction time and have a low tolerance for extended activities. These muscles are used primarily for anaerobic activities, or exercise that is conducted in quick, strong bursts. These fast twitch or short muscle fibers are divided into two categories: A, and B. Fast twitch A fibers are used for "prolonged" anaerobic activity, such as sprinting 400 meters or swimming a 50 meter race. Fast twitch B fibers have an extremely low resistance to fatigue-- these muscles tire the most easily of any muscle fibers. B fibers are used for very short anaerobic activities such as heavy weight lifting, extremely short sprints (50-100 meters), shot put, and long jump.
There are actually three types of muscle fibers found in the human body: slow twitch, fast twitch A, and fast twitch B. Slow twitch muscle fibers are used primarily in aerobic activity. These longer muscle fibers are highly resistant to fatigue, but they have a slower contraction time than fast twitch muscles. Endurance athletes, such as distance runners, have a high percentage of slow twitch muscle fibers in the body. Furthermore, the activities of daily life, most importantly, maintaining correct posture, are run by these slow twitch or long muscle fibers.
Meanwhile, fast twitch muscle fibers have a quick contraction time and have a low tolerance for extended activities. These muscles are used primarily for anaerobic activities, or exercise that is conducted in quick, strong bursts. These fast twitch or short muscle fibers are divided into two categories: A, and B. Fast twitch A fibers are used for "prolonged" anaerobic activity, such as sprinting 400 meters or swimming a 50 meter race. Fast twitch B fibers have an extremely low resistance to fatigue-- these muscles tire the most easily of any muscle fibers. B fibers are used for very short anaerobic activities such as heavy weight lifting, extremely short sprints (50-100 meters), shot put, and long jump.
