Compared to fast twitch muscle fibers, slow-twitch fibers _____. A are able to produce much greater force during contractions B "have more myoglobin, more mitochondria, and greater endurance" C "are lighter in color, wider in diameter, and receive less blood flow" D cannot maintain contractions as long because they have fewer mitochondria
| A |
are able to produce much greater force during contractions
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| B |
"have more myoglobin, more mitochondria, and greater endurance"
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| C |
"are lighter in color, wider in diameter, and receive less blood flow"
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| D |
cannot maintain contractions as long because they have fewer mitochondria
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Fast Twitch Muscle Fiber Types. The two types of skeletal muscle fibers are slow-twitch (type I) and fast-twitch (type II). Slow-twitch muscle fibers support long distance endurance activities like marathon running, while fast-twitch muscle fibers support quick, powerful movements such as sprinting or weightlifting. Slow-twitch muscle fibers are fatigue resistant, and focused on sustained, smaller movements and postural control. They contain more mitochondria and myoglobin, and are aerobic in nature compared to fast-twitch fibers. Slow-twitch fibers are also sometimes called type I or red fibers because of their blood supply. Fast-twitch muscle fibers provide bigger and more powerful forces, but for shorter durations and fatigue quickly. They are more anaerobic with less blood supply, hence they are sometimes referred to as white fibers or type II.
Slow twitch muscle fibers produce low force during contraction. Hence the option A is incorrect.
Slow twitch muscle fibers contain more mitochondria and myoglobin, more enduring and are aerobic in nature compared to fast-twitch fibers. Hence the option B is correct.
Slow-twitch fibers are also sometimes called type I or red fibers because of their blood supply. They are more anaerobic with less blood supply, hence they are sometimes referred to as white fibers or type II. Hence the option C is incorrect.
Slow-twitch muscle fibers are fatigue resistant, and focused on sustained, smaller movements and postural control. They contain more mitochondria and myoglobin, and are aerobic in nature compared to fast-twitch fibers. Hence the option D is incorrect.
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