Hypertrophy refers to the increase in the size of muscle cells, resulting in larger muscle mass. This process typically occurs as a response to resistance training or Weightlifting, where muscles are subjected to stress, leading to microtears that the body repairs and strengthens. There are two main types of hypertrophy: myofibrillar, which increases muscle strength, and sarcoplasmic, which enhances endurance by increasing the volume of sarcoplasmic fluid in the muscle cells. Overall, hypertrophy is a key factor in physical training and bodybuilding.