Protein is necessary for all biochemical processes that take place in the body. For example: the growth and repair of tissue, maintaining you immune system, transporting of molecules and the production of hormones and enzymes.
It may also be used as an energy source by the body when the main sources (carbohydrates and fats) are depleted.
The importance of protein in sports
Research indicates that individuals involved in regular physical activity require higher daily amounts of protein than sedentary ones (between 1.4 and 2 grams per kg) (*1). Food can provide most of the protein needed by athletes though in most cases protein supplementation is necessary to meet daily requirements.
Consuming adequate amounts of protein will allow your body to repair training-induced micro-tears in the muscle and grow stronger. Whether it's bodybuilding, crossfit, football, tennis, swimming or any other sport, protein supplements are a convenient way of adding protein to one's diet.