Protein, which is supplemented before training every day, is digested and hydrolyzed into amino acids, which are absorbed in the body to synthesize the protein needed by the human body. At the same time, the new protein is constantly metabolized and always in a dynamic balance. Therefore, the quality and quantity of food protein and the proportion of various amino acids are all related to the amount of protein synthesized by the human body, especially the growth and development of teenagers, the prenatal and postnatal care of pregnant women and the health and longevity of the elderly, which are closely related to the amount of protein in the diet.

Protein is the main component of human body, which is more important for human activities. During exercise, after the human body has consumed the stored sugar, it will start to consume protein. Therefore, supplementing protein after exercise can supplement the consumed glycogen, provide energy for the body and help the body recover. For people who want to exercise muscles, protein is the raw material for muscle growth, and the speed of protein synthesis determines the speed of muscle growth, which plays an important role in the composition, growth and fruiting of muscle groups.

During exercise, the synthesis and catabolism of protein are strengthened; When the amount of exercise training increases, the excretion of nitrogen and sulfur in athletes' urine increases obviously, which can lead to negative nitrogen balance, decreased hemoglobin and serum protein content, and increased non-protein nitrogen content in blood. When the skin sweats at high temperature, it will lose a lot of nitrogen. Protein nutrition can supplement the consumption of exercise, promote the synthesis and tissue repair of protein such as muscle and blood, help to enhance the excitability of athletes' system, strengthen nerve reflex activities and improve hormone effect.

Protein intake should be coordinated with the amount of exercise training. The daily demand of protein is generally about 1 kg 1- 1.5g per day. For people who don't exercise, it is enough to consume 0.8g protein per kg of body weight every day. For bodybuilders and other sports practitioners, it is even more necessary to supplement.