Question

Athletes who excel at endurance activities have a higher-than-normal percentage of slow fibers. Slow fibers are physiologically better adapted to this type of activity than are fast fibers, which are less vascular and fatigue faster. What type of fibers are athletes who excel at endurance activities more likely to have?

1) Slow fibers
2) Fast fibers
3) Both slow and fast fibers
4) No fibers

Answer 1

Athletes who excel in endurance activities have a higher percentage of slow-twitch muscle fibers, which allow them to perform longer due to more mitochondria and myoglobin.

Step-by-step explanation:

Athletes who excel at endurance activities are more likely to have a higher percentage of slow fibers, also known as slow-twitch muscle fibers. These fibers are physiologically better adapted for endurance because they have more capillaries, mitochondria, and myoglobin, allowing them to carry more oxygen and sustain aerobic activity for a longer period of time. In contrast, fast fibers or fast-twitch muscle fibers fatigue much faster as they contain fewer capillaries and mitochondria, making them suitable for short bursts of activity but not endurance. Genetically, individuals may have a predisposition towards a higher proportion of one type of these muscle fibers.