True about type 2 muscle fibre
## Core Concept
Type 2 muscle fibers, also known as fast-twitch fibers, are one of the two main types of skeletal muscle fibers, the other being Type 1 (slow-twitch) fibers. These fibers are specialized for short-duration, high-intensity activities. They are less efficient at using oxygen to generate more fuel (ATP) for continuous, long-term activities.
## Why the Correct Answer is Right
Type 2 muscle fibers are characterized by their **low myoglobin content**, **low mitochondrial density**, and a **high glycolytic capacity**. This allows them to rapidly generate energy through anaerobic glycolysis, making them ideal for explosive, short-duration activities. Their **large diameter** and **low capillary density** also distinguish them from Type 1 fibers.
## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but generally, any statement contradicting the characteristics of Type 2 fibers (e.g., high myoglobin content, high mitochondrial density) would be incorrect.
- **Option B:** Similarly, without the specific content of Option B, any statement not aligning with Type 2 fiber properties (e.g., suggesting they are primarily aerobic) would be incorrect.
- **Option D:** This option would be incorrect based on the specific characteristics attributed to Type 2 muscle fibers, such as their reliance on anaerobic metabolism.
## Clinical Pearl / High-Yield Fact
A key point to remember is that **Type 2 muscle fibers are more prone to fatigue** because they rely heavily on anaerobic glycolysis for energy production, which leads to a rapid accumulation of lactic acid. This is in contrast to Type 1 fibers, which are more fatigue-resistant due to their reliance on oxidative phosphorylation.
## Correct Answer: B.