The muscular enlargement described as primarily an increase in cross-sectional area, with greater actin and myosin content and more myofibrils, is called what?

The muscular enlargement described as primarily an increase in cross-sectional area, with greater actin and myosin content and more myofibrils, is called what?

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

Answer: (D)

Hypertrophy. Muscle fiber growth that increases the cross-sectional area involves adding more contractile proteins (actin and myosin) and more myofibrils, making the fiber thicker and capable of producing greater force. This is the classic adaptation to resistance training—fittingly called hypertrophy. Atrophy would be the opposite, a decrease in size. Hyperplasia would mean more muscle fibers (increase in cell number), which is not the typical response in adult skeletal muscle. Fatigue is a temporary decline in performance due to metabolic factors, not a structural enlargement.

Hypertrophy.

Muscle fiber growth that increases the cross-sectional area involves adding more contractile proteins (actin and myosin) and more myofibrils, making the fiber thicker and capable of producing greater force. This is the classic adaptation to resistance training—fittingly called hypertrophy.

Atrophy would be the opposite, a decrease in size. Hyperplasia would mean more muscle fibers (increase in cell number), which is not the typical response in adult skeletal muscle. Fatigue is a temporary decline in performance due to metabolic factors, not a structural enlargement.