There is a big tiger with a white forehead on Jingyanggang, and its eyes are hanging, which has killed twenty or thirty people. In the past, businessmen, villagers and others could only walk together for three hours. Song Wu has plenty of food and drinks in the hotel. He didn't take the bartender's advice. He simply went to Jingyanggang with a whistle stick. At that time, it was time to apply for a license. Song Wu was drunk and became very excited. He saw a big bluestone shaking by the roadside and wanted to lie down and have a rest. Suddenly, a colorful tiger came at him. Song Wu was surprised and the wine woke up, so he turned over to avoid it. Song Wu saw an opportunity. When the tiger appeared again, he grabbed the tiger's head with both hands and pressed it down. The tiger struggled desperately. Song Wu tried to hold it down and beat it in the face and eyes with all his strength. The tiger was still killed alive.

Song Wu is eight feet long and has great strength. He killed a tiger with his bare hands. Where did such great power come from?

We can see that when a weightlifter lifts a barbell of several hundred kilograms, all his muscles are bulging, which shows that the intense contraction of muscles has produced great strength. Well-defined muscles not only give people a sense of beauty, but also give them a sense of manpower. People's strength comes from muscles.

Human muscles, large and small, count down to more than 600 pieces, accounting for about 40% of the body weight. These long and short muscles can stretch and contract, bend and rotate synchronously, and perform some functions under the command of the nervous system. Without the efforts of these muscles, the human body can't do anything, even life can't be maintained. Muscle is made up of countless muscle cells. Muscle cells are thin and long, just like cotton fibers, so they are called muscle fibers. According to different muscle tissue distribution and skills, muscles can be roughly divided into skeletal muscle, smooth muscle and myocardium. Skeletal muscle is named because it is mostly attached to the bones of trunk and limbs. It is fixed on the bones through tendons, which drives the bones and joints and enables people to make various postures and movements. The fiber of skeletal muscle is like a long cylinder, which is dominated by human will. How strong a person is depends mainly on the flexibility of these muscles attached to bones. Although the contraction of skeletal muscle is rapid and powerful, it is not lasting, with poor endurance and easy fatigue.

Muscle contraction can produce great strength. According to calculation, if the muscles of 6 square centimeters contract at the same time, they can lift 20-60 kilograms. It is estimated that if 300 million muscle fibers in the human body contract in one direction at the same time, the strength can reach 25 tons, equivalent to a crane. People who exercise regularly have strong muscles, thick muscle fibers and great strength. Research shows that a healthy young man can increase his muscle strength by 50% through half a year's strength training. Song Wu likes playing with guns and practicing martial arts since he was a child. His muscle strength is the result of long-term exercise. Muscle movement is controlled by the brain. In the case of saving lives, saving lives or threatening lives, the human body will have an emergency mechanism. At this time, the spirit is highly nervous, the nerve cells are extremely excited, and the energy stored in the muscles is mobilized to the maximum extent, which can play an extraordinary level.