Regular exercise also has an impact on the inside of the human body. The metabolism of human body is vigorous, the capillaries in muscles increase, and the blood flow increases, so that the blood supply in the body is good, the absorption and storage capacity of nutrients such as protein is enhanced, muscle fibers are thickened, and muscle volume is increased. Therefore, muscles become more robust, strong, developed and powerful. In addition, due to the change of muscle structure, the enhancement of enzyme activity and the improvement of nerve regulation, the function of muscle has been improved, which is characterized by strong contraction, fast speed, good elasticity and strong endurance.