Weight training is the best way to build extra muscle and body size.
Build is their muscle size. An average man over 20 would be either high build or medium build.
The three all-round power exercises that will build all body muscle areSquatsBenchpressDeadliftWith these three alone you can gain substantial size
lower weight and reps gradually. dont exercise with heavier weights because this build muscle. but stopping immediately is hard for the body. slowly lowering the weight will help to safely lower the size of any muscle.
Preteens and young teens bodys does not produce enough hormones to allow the body to bulid big muscles.
tongue
tongue
the tounge is the stongest muscle in the body according to it's size
The strongest muscle for its size in the human body is the tongue
If you are talking about actual mass size, the quadriceps and hamstrings would be the largest muscle group in the body.
Most body builders eat eggs and bread. Eggs have a tremendous amount of protein for their size that helps maintain muscle growth and development. Bread restores loss carbohydrates as a matter of replenishing energy.
Eccentric training does favor strength. It does build more muscle strength and endurance than muscle growth.
The difference between muscle mass and muscle hypertrophy is that muscle hypertrophy is the increase in size of skeletal muscle while muscle mass is the weight of your body muscle.