What best defines muscle hypertrophy?

Muscle hypertrophy is best defined as an increase in muscle size. This biological process occurs primarily as a response to resistance training or weightlifting, where the muscle fibers experience stress and subsequently adapt by increasing in size. When the muscle fibers are subjected to sufficient tension during workouts, they go through microtears, and the repair process leads to thicker fibers. This is particularly evident in skeletal muscles, which are the muscles attached to bones that allow for movement.

Understanding that muscle hypertrophy is specifically related to size is crucial, as it distinguishes it from other physical adaptations such as increased aerobic capacity, muscle endurance, or fat storage. Increases in aerobic capacity relate to the efficiency of oxygen usage during prolonged exercise, while muscle endurance pertains to the ability of muscles to sustain prolonged activity. Lastly, increased fat storage does not contribute to muscle hypertrophy; instead, it refers to the accumulation of fat tissue in the body. Thus, the hallmark of muscle hypertrophy is the enlargement of muscle fibers, which is fundamental in strength training and bodybuilding contexts.