Who explained the biochemical changes occurring during muscle contraction?

Explanation

**Step-by-Step Solution:**

1. **Understanding Muscle Contraction**: Muscle contraction is a complex process that involves biochemical changes in muscle fibers. The primary proteins involved in this process are actin and myosin.

2. **Sliding Filament Theory**: The mechanism of muscle contraction is explained by the sliding filament theory. According to this theory, during contraction, actin filaments slide over myosin filaments, leading to shortening of the muscle.

3. **Biochemical Changes**: During muscle contraction, ATP (adenosine triphosphate) is hydrolyzed to ADP (adenosine diphosphate) and inorganic phosphate. This hydrolysis provides the energy needed for the contraction process.

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