Classification of muscles:
skeletal muscle
It is a type of muscle that can be seen and touched. When bodybuilders increase muscle strength through exercise, they exercise skeletal muscle.
Skeletal muscles are attached to bones and appear in pairs: one muscle moves bones in one direction and the other moves bones in the opposite direction. These muscles usually contract at will, which means that when they want to contract muscles, the nervous system will instruct them to do so. Skeletal muscle can contract for a short time (twitching) or for a long time (tetanus).
Red and white muscle fibers
Skeletal muscle of human body can be divided into red muscle and white muscle. Red muscle fibers rely on hemoglobin for continuous oxygen supply and long-term contraction and stretching, so that we can carry out daily behavior activities. White muscle fibers expand and contract rapidly through internal rapid chemical reaction (mostly in emergency), which is characterized by long duration and short reaction time, and its reaction time is one quarter of that of red muscle fibers.
smooth muscle
It exists in digestive system, blood vessels, bladder, respiratory tract and female uterus. Smooth muscle can stretch and maintain tension for a long time. These muscles don't contract at will, which means that the nervous system will automatically control them without thinking. For example, the muscles of the stomach and intestines perform tasks every day, but people generally don't notice them.
myocardium
Only in the heart, its biggest feature is endurance and firmness. It can stretch as limited as smooth muscle or contract as powerfully as skeletal muscle. It's just a twitching muscle that doesn't automatically contract. The heart muscle has a fixed contraction law, thus producing a heartbeat. Normal pacemaker cells are normal, and the regularity of myocardial contraction is certain. If pacemaker cells are abnormal, the regularity of myocardial contraction will change.
Extended data:
Methods to improve muscle density:
1, long displacement:
No matter rowing, bench pressing or bending, you should first put the dumbbell as low as possible, so that the muscles can be fully stretched, and then raise it as high as possible. This article sometimes conflicts with "continuous tension", and the solution is to quickly pass the "locked" state. However, I don't deny the role of heavy half-course exercise.
2. Slow:
Lift up slowly and put it down slowly, which will stimulate the muscles deeper. Especially when putting down the dumbbell, we should control the speed and do concession exercises, which can fully stimulate the muscles. Many people ignore the concession movement, even if they lift dumbbells, they will soon put down their tasks and waste a good opportunity to increase their muscles.
3. High density:
"Density" refers to the rest time between the two groups, and the rest time of 1 minute or less is called high density. To increase muscle mass rapidly, it is necessary to take less rest and stimulate muscles more. "Multi-group number" is also based on "high density". When you exercise, you should concentrate on training like a war, and don't think about anything else.
4. Peak shrinkage:
This is a main rule that makes muscle lines very obvious. It requires that when an action reaches the most tense position of muscle contraction, it should maintain the most tense state, do static exercises, and then slowly return to the starting position of the action. My method is to count 1 ~ 6 when you feel the most tense muscles, and then put it down.
5. Persistent nervousness:
The whole group of muscles should be kept tense. No matter whether the exercise starts or ends, don't let it relax (don't be in a "locked" state) and always reach complete exhaustion.
6. Relaxation among groups:
Stretch and relax after each group of actions. This can increase the blood flow of muscle, and also help to eliminate the waste deposited in muscle, accelerate the recovery of muscle and quickly supplement nutrition.
Baidu encyclopedia-muscle
Baidu encyclopedia-human body fat
Baidu encyclopedia-muscle density