Which of the following types of muscle fibers have low myosin ATPase activity and are classified as slow-twitch?

a. Type I fibers

b. Type IIa fibers

c. Type IIx fibers

d. Type III fibers

Video transcript

Hi, everyone. Let's take a look at this practice problem together which muscle fibers are well suited for activities requiring quick powerful bursts of energy such as sprinting or weightlifting. The answer options are a type one B, type two C, type three and D type one A recall that there are two main types of muscle fibers. They can be described as either slow twitch or fast twitch. Slow twitch, muscle fibers do not easily fatigue and produce low power contractions over longer periods of time. Slow twitch, muscle fibers are also known as type one fibers. So again, they do not fatigue quickly but they produce lower power contractions. Fast twitch. Muscle fibers produce big and powerful contractions. However, it's only for a short amount of time because they fatigue very quickly. Fast twitch. Muscle fibers are also known as type two fibers. So we can go ahead and eliminate options C and D because type three and type one A are not terms used for muscle fiber classification. And the question remember ask which muscle fiber produces quick powerful bursts of energy. That is your fast twitch or type two fibers. So the correct answer is option B type two. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.