Section 1: Osteoliac Muscles
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| The Human Athletic |
All activities of the human body are realized by the locomotor system of the human body. The locomotor system is composed of three main parts: the bone, the guan, and the rational and rational reticulation. The motor function of the locomotor system builds the rotation of the muscles and the reins of the bottle. So the ability of the human body to move depends on the muscles.
1. Muscles
1.1, Muscle tissue and muscle strength
Muscles make up about 40% of the total body weight and are distributed in all parts of the human body. Muscles are made up of muscle fibers, which are about 0.1 cm in diameter, and their length varies depending on the size of the muscle, ranging from 0.5 cm to 14 cm. A muscle is made up of 100,000 to 1,000,000 muscle fibers. The ends of each muscle form tendons, which are extremely strong, inelastic, and firmly attached to the bone. Long muscle fibers usually make up muscle bundles, which are made up of muscle mass.
The muscle can contract to half of its normal length, and the muscle contraction does the work to produce force, which is the exhaustion of internal energy. This ability to do work is related to its length, and the longer the muscle, the greater its ability to do work. In order to increase muscle length, athletes often do stretching activities. Muscle fibers have many very fine protein filaments, which are thick and thin, forming a system that can contract. Each muscle fiber can contract with a certain amount of force; muscle strength is the sum of the contraction force of many muscle fibers, in general. 1) muscle strength is related to the cross-sectional area of the muscle; the more muscle fibers used in a movement, the greater the force that can be exerted; b12>2) maximum muscle strength is generated when the length of the muscle is the length of its resting state. And as its length shortens, the ability of the muscles to produce muscle strength gradually decreases. /b14>3) The mechanical action of the bone is the lever, to which the muscles are attached, and the nodes of the bone are determined to an angle at which the maximum force can be exerted; /b16>4) Under the same training conditions, women's muscle strength is about 30% smaller than that of men due to their smaller muscles (Yang Gongxia, 2000).
1.2, two forms of muscle contraction
Muscle contraction is divided into isometric contraction, centripetal contraction, and eccentric contraction due to the change in muscle length. The former is when the muscle pull is equal to the external resistance, the length of the muscle does not change, and this contraction is necessary when holding weights or maintaining body posture. Because it is not displaced, the muscles do not do mechanical work. The latter two are muscle tension, and the length of the muscle should be changed when the muscle tension is not equal to the external resistance. When the muscle pulls more than the external resistance, the muscle shortens. This is called centripetal contraction and is restraint work. Because of the displacement generated, the muscles do mechanical work (external work). When the muscle pull is less than the external resistance, the muscle is stretched, although it is contracting. This is called an eccentric contraction or a superisometric contraction. At this time, the muscles do negative mechanical work (internal work), and the muscles cannot use this energy to do work but convert it into heat.
The process of muscle contraction has electrical activity, which is very similar to the electrical phenomenon of nerve impulses. This electrical activity can be recorded when magnified, and this recording is called electromyography. The recorded electrodes are pressed against the skin surface outside the muscle, which reflects the electrical activity of the entire muscle. If the electrodes are inserted into the human muscle in a needle-like shape, the electrical activity of a single muscle fiber can also be measured.
2. Bone and bone
There are 200 whole bones in the human body. The human bone sales system is a number of Peng knot files from Kegong fat and fragrant chest shops. According to the work atmosphere, the year can win three parts. The bones include 8 pieces of Gu bones and 15 co-faceted Gu Tsai. Brain frequency material is sour; the national magnet is located in the technique. Mangs play the role of Tibetan protection and protection. The facial bones make up the eye sockets, elephant fat, and mouth rash. The expelling bones include the vertebrae, sternum, and drowsiness and have a supportive and protective effect. The limb bones are further divided into upper gel bones and lower rubber backs. In the human strip, there is a system of desolation, and the column and the flesh make the bone have a particularly close relationship with the manipulation activity.
The spine is composed of 24 vertebrae, 5 bones, and 4 coccyxes, and its shape is shown in Figure 2-1. The vertebrae include cervical (7), thoracic (12), and lumbar (5). Each vertebra can be intersected by pushing bodies and breeding horses. The vertebral arch encloses the foramina. The vertebral foramina of the anterior and posterior bones are connected to form the right canal, in which the spinal cord is located. There is a vertebral hole between the two adjacent floors, through which the spine material passes.
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| Anterior, posterior, and lateral elevations of the spine |
There are intervertebral discs connecting the vertebrae. The shape of the disc is consistent with that of the vertebral body. It consists of a fibrocartilage ring and a colloidal nucleus pulposus. The interforest disc is tough and elastic, so it can withstand large amounts of gravity and has a certain degree of mobility. The intervertebral disc in the lumbar spine is thicker than the other part, so it can move more widely. When a lumbar sprain or lumbar movement is too strenuous, it can produce fibrocartilage rings, which can cause a herniated disc.
The bones of the limbs include the upper gel bones and the lower limb bones. The left and right upper limb bones are made up of 32 bones, divided into the clavicle, scapula, humerus, ulna, radius, carpal bone, metacarpal bone, and phalanges. The bones of the lower limbs are also divided into left and right limbs. Each lower limb bone is made up of 30 bones. They are: hip, ischium and pubis, femur, tibia and fibula, tarsus, metatarsal, and phalanges.
3. Joints
There are two types of connections between bones, namely direct connections and indirect connections. Direct connections mainly rely on ligaments or cartilage connections, such as suture connections of the parietal bones of the skull, intervertebral disc connections between vertebral bones, etc. Directly connected bones cannot do any movement or can only do very limited movement. All parts that can do a large range of activities are indirectly connected through various joints between the bones. The bones of the human limbs are generally connected by joints. The main function of the joint is to make it possible for the human limb to perform activities such as stretching, wrapping, and rotating. If the limbs are not able to perform these movements, it is impossible to achieve even the simplest movements, such as walking and holding objects. There are four types of nerve endings in the joints called type 1, type 1, and "IV."These nerve endings transmit information about joint activity to the brain, which analyzes and synthesizes nerve impulses to regulate muscle and joint activity.
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