What happens to a muscle when it contracts?

Explanation

**Step-by-Step Solution:**

1. **Understanding Muscle Contraction**: When a muscle contracts, it undergoes a process known as pulling. This is the fundamental action of muscles when they are activated.

2. **Example of Muscle Contraction**: Consider the action of lifting an object from the ground. When you attempt to lift something, the muscles in your hand and arm are engaged.

3. **Changes in Muscle Structure**: During contraction, the muscles become shorter and thicker. This change in structure is crucial for the muscle's ability to generate force.

...