The condition in which muscles waste away is known as
Muscle atrophy is when muscles waste away. It’s usually caused by a lack of physical activity. When a disease or injury makes it difficult or impossible for you to move an arm or leg, the lack of mobility can result in muscle wasting. This can occur due to degeneration of nerves also.
Muscular hypertrophy is a term for the growth and increase of the size of muscle cells. The most common type of muscular hypertrophy occurs as a result of physical exercise such as weight lifting.