FIT5 How-tos :: The effectice muscle conditioning :: Muscle building :: What are muscles?

The muscle system makes up 40% of the body weight; or more than 50% for sports people. Muscles work only as an effect of the nervous system, they cannot work individually without this: this is why concentrated muscle training is very important.

The biggest part of the muscle is muscle fibres, which contains 75% water and 20% protein, and the last 5% is made up of carbohydrates, fats and mineral salts.