When people exercise, due to the increase of energy consumption in the body, the metabolites increase, that is, the intensity of contraction increases, the number of contractions increases, and the blood circulation increases, thus ensuring the need for a higher metabolic level in the body. During exercise, the change of heart function becomes a factor to improve heart function. Long-term scientific exercise can improve the structure and function of the heart. The average person's heart volume is about 700 ml, while the athlete's is more than 1000 ml, which is physiologically called work-related hypertrophy. Hypertrophy of the heart makes the heart contract strongly and increases the cardiac output per stroke. The average person's heartbeat (heart rate) is about 70 times per minute, the athlete's is about 60 times, and the excellent long-distance runner's is about 40 times. This kind of heart is not easy to get tired, and it has a large reserve function, which is of course good. Regular scientific physical exercise can improve the structure and function of the heart. The human digestive system is like a food processing factory. Its function is to digest and absorb nutrients. The digestive tract mainly consists of mouth, pharynx, esophagus, stomach, small intestine, large intestine and anus, as well as salivary glands, liver and pancreas. The food we usually eat must be digested by the digestive tract and processed by the pancreas before it can become a nutrient that the human body can absorb and utilize. During physical exercise, the metabolism is greatly strengthened than usual, and a lot of nutrients are consumed in the body. During physical exercise, the metabolism increases by 10 times or even 20 times.

After physical exercise, the substances consumed in the body should be replenished in time, which is bound to absorb more substances from the outside and become substances in the body through the processing of the digestive system. Obviously, the work of the digestive system is much bigger than before, so that the function of the digestive system is improving day by day. The activities of all human organ systems are directed and managed by the nervous system. During exercise, the nervous system strengthens the command of the motor organs, heart, lungs and other organs, and at the same time reduces the management of the digestive system, so that the activities of the digestive system are relatively inhibited to ensure the vigorous activities of muscles and heart during exercise. After exercise, the nervous system strengthens the command of the digestive system, the activity of the digestive system is strengthened, and more nutrients are absorbed, thus improving the digestive ability. During exercise, due to the deepening of breathing, the activities of diaphragm and abdominal muscles increase, diaphragm moves up and down greatly, and abdominal muscles move back and forth, which plays a massage role in gastrointestinal tract. After the exercise, this massage will last for a period of time, thus promoting the activities of the gastrointestinal tract and improving the function of the digestive system. Regular physical exercise can increase vital capacity.