Anaerobic work becomes painful due to the accumulation of

Options

A. `Ca^(+)` ions
B. Myosin
C. Lactic acid
D. Creatine phoshate

Answer

### Step-by-Step Solution:

1. **Understanding Anaerobic Work**:
- Anaerobic work refers to physical activity that occurs when there is insufficient oxygen available to the muscles. This typically happens during intense exercise when the demand for oxygen exceeds the supply.

2. **Incomplete Breakdown of Glucose**:
- In the absence of adequate oxygen, glucose (C6H12O6) cannot be fully oxidized. Instead, it undergoes an incomplete breakdown process.

3. **Production of Lactic Acid**:
- During anaerobic respiration, glucose is converted into lactic acid (C3H6O3) along with the release of energy. This process occurs primarily in the cytoplasm of muscle cells, particularly in voluntary muscle cells.

4. **Accumulation of Lactic Acid**:
- As lactic acid accumulates in the muscles due to prolonged anaerobic activity, it leads to a decrease in pH within the muscle cells, resulting in discomfort and pain, commonly referred to as muscle cramps.

5. **Re-oxygenation and Complete Breakdown**:
- Once sufficient oxygen becomes available again, lactic acid can be converted back into glucose or fully oxidized into carbon dioxide (CO2) and water (H2O), alleviating the pain and restoring normal muscle function.

### Final Answer:
Anaerobic work becomes painful due to the accumulation of **lactic acid**.

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