Which term describes an increase in muscle size due to training?

• A. Hypertrophy
• B. Hyperplasia
• C. Atrophy
• D. Metaplasia

Answer: (A)

Muscle growth from training is best described as hypertrophy, the enlargement of muscle fibers in response to increased workload. When you resistance-train, the fibers adapt by adding contractile proteins like actin and myosin and increasing the number of myofibrils, which thickens each fiber and raises its cross-sectional area. Satellite cells can donate nuclei to support this higher protein synthesis, helping fibers grow larger. This is distinct from hyperplasia, which would mean more muscle cells rather than bigger ones (and is minimal in human skeletal muscle). Atrophy refers to shrinking from disuse or disease, and metaplasia is a change from one mature cell type to another, not about size increase due to training.