Define sliding filament theory of muscle contraction.

Explanation

**Step-by-Step Text Solution:**

1. **Introduction to the Theory**: The sliding filament theory explains the mechanism of muscle contraction at the molecular level.

2. **Components Involved**: The theory involves two types of filaments in muscle fibers: myosin (thick filaments) and actin (thin filaments).

3. **Mechanism of Contraction**: According to the sliding filament theory, during muscle contraction, the myosin filaments slide past the actin filaments.

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