Red muscle fibres can continue contracting for prolonged durations without fatigue. Why?

Explanation

**Step-by-Step Solution:**

1. **Understanding Red Muscle Fibers**: Red muscle fibers, also known as slow-twitch fibers, are characterized by their red color due to the presence of myoglobin, a protein that binds oxygen. This property allows them to utilize oxygen efficiently for energy production.

2. **Role of Mitochondria**: These fibers are rich in mitochondria, which are the cell's powerhouses. Mitochondria are responsible for aerobic respiration, a process that generates ATP (adenosine triphosphate), the energy currency of the cell. The presence of a high number of mitochondria enables red muscle fibers to produce energy continuously over long periods.

3. **Aerobic Respiration vs. Anaerobic Respiration**: Red muscle fibers primarily rely on aerobic respiration, which requires oxygen. This process is efficient and produces a large amount of ATP without the accumulation of lactic acid, which is a byproduct of anaerobic respiration (which occurs when oxygen is scarce).

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