How Your Muscles Change With Exercise

Muscle size increases when a person continually challenges the muscles to deal with higher levels of resistance or weight. This process is known as muscle hypertrophy.
Muscle hypertrophy occurs when the fibers of the muscles sustain damage or injury. The body repairs damaged fibers by fusing them, which increases the mass and size of the muscles.
Certain hormones, including testosterone, human growth hormone, and insulin growth factor, also play a role in muscle growth and repair.These hormones work by:
improving how the body processes proteins
inhibiting the breakdown of protein
activating satellite cells, which are a type of stem cell that plays a role in muscle development
stimulating anabolic hormones, which promote muscle growth and protein synthesis
enhancing tissue growth
Strength and resistance training can help the body:
release growth hormone from the pituitary gland
stimulate testosterone release
improve the sensitivity of the muscles to testosteroneBoth males and females can have the following body shapes, and each requires a different approach to muscle building:
Mesomorphic: People with this body type tend to be muscular and generally build muscle mass far more quickly than people with other body types.
Ectomorphic: This term describes a slim or straight frame. Ectomorphs have a lower chance of building muscle mass but can increase their strength through resistance training.
Endomorphic: This body type is more rounded or curvy. People with an endomorphic body can build muscle most effectively through strength training.
However, in an interview with Australian news service ABC, sports scientist Dr. Tony Boutagy points out several traits that are more pronounced in males and support faster muscle growth. These include a larger muscle mass, higher testosterone, and tighter joints.