Question

Type I fibers have limited anaerobic capacity, compared to type IIa and Iix fibers, and are primarily aerobic due to the fact they contain a larger amount of

1. mitochondria
2. oxidative enzymes
3. myoglobin
4. all of these

Answer 1

Type I muscle fibers are primarily aerobic and possess a higher quantity of mitochondria, oxidative enzymes, and myoglobin, which collectively enable them to sustain muscle activity for extended periods without rapid fatigue.

Step-by-step explanation:

Type I muscle fibers, also known as slow oxidative (SO) fibers, have limited anaerobic capacity and are primarily aerobic. They contain a larger number of mitochondria, which is critical for aerobic metabolism that uses oxygen in the metabolic pathway. These fibers also have an abundance of oxidative enzymes that facilitate aerobic energy production. Additionally, type I fibers have a high amount of myoglobin, an oxygen-carrying molecule that stores oxygen within the fibers, contributing to their aerobic capacity and endurance. Hence, type I fibers are well-equipped for activities requiring endurance as they can produce large quantities of ATP for muscle activity that does not fatigue quickly.