Experiments show that protein absorbed quickly, such as whey protein, has little effect on muscle growth before and immediately after exercise, while protein, such as egg white, is not easy to digest and can be eaten before exercise 1 hour, which is the best for muscle growth. Milk contains whey protein, which can be drunk before and after practice. At the same time, the most protein content in milk is casein, which belongs to indigestible protein, and its longest digestion time is 7 hours, so drinking milk before training is better for muscle exercise.