During exercise, myocardial excitability increases, coronary artery dilates, myosin ATPase activity increases, and the interaction between myosin and myofibrillar protein increases, thus improving myocardial contractility. Long-term exercise can increase myocardial glycogen content, myoglobin, hexokinase activity and myocardial ability to absorb blood sugar, enhance blood lactic acid oxidation ability and tissue respiration ability, and improve cardiac function reserve. People who exercise regularly have strong heart muscles and a strong "reserve" of the heart.
In the process of exercise, muscle activity increases the body's demand for oxygen, and at the same time increases the carbon dioxide produced, thus stimulating the respiratory center, deepening and accelerating breathing, inhaling more oxygen and discharging too much carbon dioxide. People who exercise for a long time have developed respiratory muscles, increased thoracic movement and diaphragm contraction, and increased thoracic volume, thus increasing vital capacity. People who often do physical exercise can increase their breathing capacity per minute by 10 times or more when doing strenuous activities, and their "vitality" is more vivid. In fact, adolescence is a period of gradual development of human internal organs and the most plastic period. Don't lose this excellent exercise time.
Studies in modern medicine and sports science show that physical exercise can play the following roles. (1) Prevent cardiovascular diseases. Cardiovascular disease is the number one killer endangering human life in the world today. According to reports, one in every two people who died in the United States suffered from cardiovascular disease; In China, people who died of cardiovascular diseases also ranked first. A large number of studies show that participating in regular physical exercise can significantly reduce the risk of cardiovascular disease formation and occurrence. (2) Improve the function of the respiratory system. When people breathe deeper in physical exercise, they will inhale more oxygen and expel more carbon dioxide, thus increasing their vital capacity and strengthening their lung function. People who exercise regularly have strong physical adaptability, so their breathing is smooth, deep and even, and their frequency is slow. The breathing frequency is 7 ~ 1 1 times/minute at rest, and 12 ~ 18 times/minute at rest. Women are 2 ~ 3 times faster than men. (3) Improve the function of digestive system. Physical exercise will enhance the consumption of nutrients in the body, enhance the metabolism of the whole body, and thus increase appetite; In addition, it can promote gastrointestinal peristalsis and secretion of digestive juice, improve the functions of liver and pancreas, thus improving the function of the whole digestive system and providing good material guarantee for human health and longevity. (4) improve the function of nervous system. Human activities are coordinated activities under the control of the nervous system. People who insist on exercising, especially middle-aged and elderly people, tend to show flexibility, alertness and energy, which is the performance of vigorous nervous system function. (5) Reduce the risk of diabetes. One of the characteristics of diabetes is that people's blood sugar level is very high. If it is not controlled, it will cause many other health problems, such as impaired vision and kidney deficiency. Regular physical exercise can control the improvement of blood sugar level, thus greatly reducing the possibility of individual suffering from diabetes. (6) control weight and change body shape. Obesity will affect people's normal physiological function, especially lead to heavier heart burden and shorter life span. If a person's subcutaneous fat exceeds the normal standard 15% ~ 25%, then his risk of death will increase to 30%. Because physical exercise can reduce fat, enhance muscle strength, keep joints flexible, control weight and improve body shape and appearance. (7) prolong life. A study lasting for 30 years shows that people who don't exercise are 3 1% more likely to die young than those who exercise regularly. The main reason is that regular physical exercise can prevent heart disease and cancer.