What does exercise do for muscles?

• A. Causes immediate muscle atrophy
• B. Stimulate muscle build-up
• C. Only increases endurance
• D. Has no effect

Answer: (B)

Exercise prompts muscles to grow and strengthen by triggering adaptation after use. When you work a muscle, especially with resistance training, the fibers endure tension and tiny injuries. The body responds by increasing protein synthesis and repairing the damaged fibers, adding more myofibrils and increasing the muscle’s cross‑sectional area. This process, called hypertrophy, leads to bigger, stronger muscles over time. Different types of exercise emphasize different outcomes—weight training mainly boosts size and strength, while endurance work improves stamina and the muscles’ oxidative capacity—but the overall effect on muscles is to stimulate their build‑up and improved function. Immediate atrophy doesn’t occur with regular exercise; disuse causes it, whereas proper training plus rest and nutrition promotes growth over weeks.