Fermentation is the process that causes your muscles to be sore after a long, strenuous workout.

Answer

**Step-by-Step Solution:**

1. **Understanding Fermentation**: Fermentation is an anaerobic process that occurs when there is a lack of oxygen. It allows cells to generate energy without oxygen.

2. **Glycolysis Process**: During strenuous exercise, glucose is broken down through glycolysis, producing pyruvate. This process occurs in the cytoplasm of the cells.

3. **Insufficient Oxygen Supply**: When a person exercises intensely, the demand for oxygen in the muscles exceeds the supply. This leads to anaerobic conditions.

4. **Conversion of Pyruvate**: Under anaerobic conditions, the pyruvate produced from glycolysis is converted into lactic acid instead of being fully oxidized to carbon dioxide and water. This conversion is part of the fermentation process.

5. **Lactic Acid Accumulation**: The lactic acid produced accumulates in the muscles, leading to muscle fatigue, cramps, and soreness. This is a common experience after intense workouts.

6. **Post-Exercise Recovery**: After the exercise, when oxygen becomes available again, the lactic acid can be converted back into pyruvate, and subsequently into carbon dioxide and water, during the recovery phase.

7. **Conclusion**: Since lactic acid accumulation in muscles is indeed caused by fermentation during anaerobic conditions, the statement that "Fermentation is the process that causes your muscles to be sore after a long, strenuous workout" is true.

**Final Answer**: True

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