1. Systematic running can thicken muscle fibers and increase muscle volume, so muscles look developed, firm, strong, symmetrical and powerful. Normal people's muscles account for 30%-40% of their body weight, while people who often engage in physical labor and physical exercise have developed muscles and their body weight can account for 50% of their body weight.
2. Regular running can change the chemical composition of muscle tissue. Such as myoglycogen, myosin and myoglobin. Fibrin and myosin are the basic substances of muscle contraction. The increase of these substances not only improves the contractility of muscles, but also enhances the activity of phosphate glands and accelerates the decomposition. Myoglobin can bind to oxygen. The increase of myoglobin content increases the oxygen reserve in muscle, so that muscle can still carry out high-intensity work under the condition of insufficient oxygen supply.
When the human body is at rest, there are only 80 open capillaries per cubic millimeter of muscle. When the muscles do strenuous exercise, not only the capillary diameter increases, but also a large number of "spare" capillaries are opened. At this time, the number of open capillaries per cubic millimeter of muscle can reach 2000 to 3000, which is higher than that at rest. 30 times as big. At this time, blood flow increases, muscle blood supply is good, and metabolism is also very strong.
4. Running exercise can improve the nervous system's ability to control muscle activity. Physical exercise has various forms, complex movements and strong skills. Regular exercise, on the one hand, can improve the nervous system's ability to control muscles, on the other hand, it can make muscles respond to nerve impulses with speed, accuracy and mobility. In this process, the ability of agonist, antagonist and synergist to cooperate with each other has been improved. Therefore, the body can coordinate freely and orderly when performing complex and difficult movements, and exert greater exercise efficiency with less energy consumption, thus improving the control ability of muscle activities.