The basic structure of exercise consists of bones, osseointegration and skeletal muscle. In the exercise system, bones play a lever role, bone connection plays a fulcrum role, and skeletal muscles play a dynamic role. Skeletal muscle must pass through at least one joint and attach to two bones.

Bone tissue is composed of living cells and minerals (mainly calcium and phosphorus), which makes bones have solid physical properties. Bones come in different shapes and sizes. For example, arm bones are long bones, wrist bones are short bones, sternum and skull are flat bones, and vertebrae are irregular bones. Adult bones are mainly composed of two kinds of tissues: hard and dense bones on the outside and porous cancellous bones on the inside.

Bone-to-bone connection refers to the connection between bones, and bone is a bone connection formed by fibrous connective tissue, cartilage or bone-to-bone connection. According to the different link modes, it can be divided into direct link and indirect link. Direct connection can be divided into fiber connection, cartilage connection and osseointegration. Indirect joint is also called synovial joint, or joint for short.

Skeletal Muscle Skeletal muscle is a kind of striated muscle, which is attached to the bone. Skeletal muscle consists of muscle cells arranged in bundles. The length of each cell is different, and the cells are closely arranged and complementary in length. There is a thin reticular membrane around each cell, which is called intramuscular membrane; Each muscle bundle is wrapped by a connective tissue membrane composed of glial fibers and elastic fibers, which is called muscle bundle membrane; On the outside of each muscle, there is 1 layer of thick connective tissue, which is called muscle adventitia.