Which type of muscle fibers are characterized as anaerobically and resistance to fatigue?

Type 2a muscle fibers are known for their characteristics that make them well-suited for activities requiring both strength and endurance. These fibers, often referred to as fast oxidative fibers, can utilize both aerobic and anaerobic energy systems. They have a relatively high resistance to fatigue compared to other fast-twitch fibers and are capable of sustaining performance over longer periods of time, making them ideal for activities that require rapid bursts of energy followed by some endurance.

In contrast, Type 1 muscle fibers, also known as slow-twitch fibers, primarily rely on aerobic metabolism and have greater endurance but lower resistance to fatigue in terms of high-intensity activities. Type 2b muscle fibers are identified as fast-twitch fibers that primarily depend on anaerobic metabolism, allowing for explosive strength but with a greater susceptibility to fatigue during prolonged activities. There are no scientifically recognized Type 3 muscle fibers in this context.

Therefore, Type 2a muscle fibers uniquely combine anaerobic capabilities with a notable resistance to fatigue, making them the correct choice for this question.