Final answer:
Muscle hypertrophy is the enlargement of muscle fibers caused by the addition of structural proteins, increasing muscle mass and strength, generally achieved through resistance training or exercise.
Step-by-step explanation:
What is Muscle Hypertrophy?
Muscle hypertrophy refers to the enlargement or increase in the size of muscle fibers. Unlike muscle hyperplasia, which is the increase in the number of muscle fibers, hypertrophy specifically involves the addition of structural proteins to existing muscle cells, thus increasing their mass and diameter. This physiological response is typically achieved through resistance training or any form of exercise that puts increased stress on the muscle fibers, prompting them to adapt and grow stronger and larger. Muscle hypertrophy plays a crucial role in increasing muscle strength and can be influenced by various factors, including hormonal changes, nutrition, and the intensity of physical activity.
The opposite condition, muscle atrophy, is the reduction in muscle size, which can occur due to lack of use, insufficient nutrition, or certain medical conditions. It is characterized by a decrease in the number of sarcomeres and myofibrils within the muscle fibers.
To summarize, the correct answer to what muscle hypertrophy is: '1) Enlargement of muscle fibers'.