Muscle Fiber Types

Our muscles are composed of two main fiber types.The first type of muscle fiber is referred to as slow  twitch fibers and is used heavily during aerobic activity activities that use oxygen and can be sustained for a fairly long period of time.Slow twitch muscle fibers have a large number of mitochondria.Remember, it is those mitochondria that let them generate ATP so efficiently.This, in turn,lets slow twitch muscle fibers fuel the repeated muscle contractions that are used in aerobic activities.Examples of aerobic activity include biking, swimming laps,and jogging.The second main type of muscle fiber is called fast twitch fibers.Fast Twitch Fibers are better suited for anaerobic exercises that require short bursts of intense activity.This is because they don't contain the amount of mitochondria that slow twitch fibers do,so they aren't as efficient when it comes to generating ATP.Remember, anaerobic activities are performed with insufficient oxygen, and examples include power lifting and short sprints.